Exclude specific backends from pruning (#262)

* Skip backends while pruning

* Add pruning test step and silence download log for better readability

* Add test cases for pruning in all backends

Also add -q or --quiet-pull to all tests.

* Add test case for skipping backends while pruning

* Adjusted test logging, generate new test spec file

* Gitignore for temp test file

.circleci/config.yml

@@ -1,72 +0,0 @@
-version: 2.1
-
-jobs:
-  canary:
-    machine:
-      image: ubuntu-2004:202201-02
-    working_directory: ~/docker-volume-backup
-    steps:
-      - checkout
-      - run:
-          name: Build
-          command: |
-            docker build . -t offen/docker-volume-backup:canary
-      - run:
-          name: Install gnupg
-          command: |
-            sudo apt-get install -y gnupg
-      - run:
-          name: Run tests
-          working_directory: ~/docker-volume-backup/test
-          command: |
-            export GPG_TTY=$(tty)
-            ./test.sh canary
-
-  build:
-    docker:
-      - image: cimg/base:2020.06
-        environment:
-          DOCKER_BUILDKIT: '1'
-          DOCKER_CLI_EXPERIMENTAL: enabled
-    working_directory: ~/docker-volume-backup
-    steps:
-      - checkout
-      - setup_remote_docker:
-          version: 20.10.6
-      - docker/install-docker-credential-helper
-      - docker/configure-docker-credentials-store
-      - run:
-          name: Push to Docker Hub
-          command: |
-            echo "$DOCKER_ACCESSTOKEN" | docker login --username offen --password-stdin
-            # This is required for building ARM: https://gitlab.alpinelinux.org/alpine/aports/-/issues/12406
-            docker run --rm --privileged linuxkit/binfmt:v0.8
-            docker context create docker-volume-backup
-            docker buildx create docker-volume-backup --name docker-volume-backup --use
-            docker buildx inspect --bootstrap
-            tag_args="-t offen/docker-volume-backup:$CIRCLE_TAG"
-            if [[ "$CIRCLE_TAG" =~ ^v[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
-              # prerelease tags like `v2.0.0-alpha.1` should not be released as `latest`
-              tag_args="$tag_args -t offen/docker-volume-backup:latest"
-              tag_args="$tag_args -t offen/docker-volume-backup:$(echo "$CIRCLE_TAG" | cut -d. -f1)"
-            fi
-            docker buildx build --platform linux/amd64,linux/arm64,linux/arm/v7 \
-               $tag_args . --push
-
-workflows:
-  version: 2
-  docker_image:
-    jobs:
-      - canary:
-          filters:
-            tags:
-              ignore: /^v.*/
-      - build:
-          filters:
-            branches:
-              ignore: /.*/
-            tags:
-              only: /^v.*/
-
-orbs:
-  docker: circleci/docker@1.0.1

.dockerignore

@@ -1 +1,7 @@
 test
+.github
+.circleci
+docs
+.editorconfig
+LICENSE
+README.md

.github/FUNDING.yml

@@ -0,0 +1,3 @@
+github: offen
+patreon: offen
+

.github/ISSUE_TEMPLATE.md

@@ -1,20 +0,0 @@
-* **I'm submitting a ...**
-  - [ ] bug report
-  - [ ] feature request
-  - [ ] support request
-
-* **What is the current behavior?**
-
-* **If the current behavior is a bug, please provide the configuration and steps to reproduce and if possible a minimal demo of the problem.**
-
-* **What is the expected behavior?**
-
-* **What is the motivation / use case for changing the behavior?**
-
-* **Please tell us about your environment:**
-  
-  - Image version:
-  - Docker version: 
-  - docker-compose version:
-
-* **Other information** (e.g. detailed explanation, stacktraces, related issues, suggestions how to fix, links for us to have context, eg. stackoverflow, etc)

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,34 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Describe the bug**
+<!--
+A clear and concise description of what the bug is.
+-->
+
+**To Reproduce**
+Steps to reproduce the behavior:
+1. ...
+2. ...
+3. ...
+
+**Expected behavior**
+<!--
+A clear and concise description of what you expected to happen.
+-->
+
+**Version (please complete the following information):**
+ - Image Version: <!-- e.g. v2.21.0 -->
+ - Docker Version: <!-- e.g. 20.10.17 -->
+ - Docker Compose Version (if applicable): <!-- e.g. 1.29.2 -->
+
+**Additional context**
+<!--
+Add any other context about the problem here.
+-->

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,28 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Is your feature request related to a problem? Please describe.**
+<!--
+A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+-->
+
+**Describe the solution you'd like**
+<!--
+A clear and concise description of what you want to happen.
+-->
+
+**Describe alternatives you've considered**
+<!--
+A clear and concise description of any alternative solutions or features you've considered.
+-->
+
+**Additional context**
+<!--
+Add any other context or screenshots about the feature request here.
+-->

.github/ISSUE_TEMPLATE/support_request.md

@@ -0,0 +1,28 @@
+---
+name: Support request
+about: Ask for help
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**What are you trying to do?**
+<!--
+A clear and concise description of what you are trying to do, but cannot get working.
+-->
+
+**What is your current configuration?**
+<!--
+Add the full configuration you are using. Please redact out any real-world credentials.
+-->
+
+**Log output**
+<!--
+Provide the full log output of your setup.
+-->
+
+**Additional context**
+<!--
+Add any other context or screenshots about the support request here.
+-->

.github/dependabot.yml

@@ -0,0 +1,10 @@
+version: 2
+updates:
+  - package-ecosystem: docker
+    directory: /
+    schedule:
+      interval: weekly
+  - package-ecosystem: gomod
+    directory: /
+    schedule:
+      interval: weekly

.github/workflows/golangci-lint.yml

@@ -0,0 +1,54 @@
+name: Run Linters
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+permissions:
+  contents: read
+  # Optional: allow read access to pull request. Use with `only-new-issues` option.
+  pull-requests: read
+
+jobs:
+  golangci:
+    name: lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-go@v4
+        with:
+          go-version: '1.21'
+          cache: false
+      - name: golangci-lint
+        uses: golangci/golangci-lint-action@v3
+        with:
+          # Require: The version of golangci-lint to use.
+          # When `install-mode` is `binary` (default) the value can be v1.2 or v1.2.3 or `latest` to use the latest version.
+          # When `install-mode` is `goinstall` the value can be v1.2.3, `latest`, or the hash of a commit.
+          version: v1.54
+
+          # Optional: working directory, useful for monorepos
+          # working-directory: somedir
+
+          # Optional: golangci-lint command line arguments.
+          #
+          # Note: By default, the `.golangci.yml` file should be at the root of the repository.
+          # The location of the configuration file can be changed by using `--config=`
+          # args: --timeout=30m --config=/my/path/.golangci.yml --issues-exit-code=0
+
+          # Optional: show only new issues if it's a pull request. The default value is `false`.
+          # only-new-issues: true
+
+          # Optional: if set to true, then all caching functionality will be completely disabled,
+          #           takes precedence over all other caching options.
+          # skip-cache: true
+
+          # Optional: if set to true, then the action won't cache or restore ~/go/pkg.
+          # skip-pkg-cache: true
+
+          # Optional: if set to true, then the action won't cache or restore ~/.cache/go-build.
+          # skip-build-cache: true
+
+          # Optional: The mode to install golangci-lint. It can be 'binary' or 'goinstall'.
+          # install-mode: "goinstall"

.github/workflows/release.yml

@@ -0,0 +1,59 @@
+name: Release Docker Image
+
+on:
+  push:
+    tags: v**
+
+jobs:
+  push_to_registries:
+    name: Push Docker image to multiple registries
+    runs-on: ubuntu-latest
+    permissions:
+      packages: write
+      contents: read
+    steps:
+      - name: Check out the repo
+        uses: actions/checkout@v3
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v2
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+
+      - name: Log in to GHCR
+        uses: docker/login-action@v2
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract Docker tags
+        id: meta
+        run: |
+          version_tag="${{github.ref_name}}"
+          tags=($version_tag)
+          if [[ "$version_tag" =~ ^v[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
+            # prerelease tags like `v2.0.0-alpha.1` should not be released as `latest` nor `v2`
+            tags+=("latest")
+            tags+=($(echo "$version_tag" | cut -d. -f1))
+          fi
+          releases=""
+          for tag in "${tags[@]}"; do
+            releases="${releases:+$releases,}offen/docker-volume-backup:$tag,ghcr.io/offen/docker-volume-backup:$tag"
+          done
+          echo "releases=$releases" >> "$GITHUB_OUTPUT"
+
+      - name: Build and push Docker images
+        uses: docker/build-push-action@v4
+        with:
+          context: .
+          push: true
+          platforms: linux/amd64,linux/arm64,linux/arm/v7
+          tags: ${{ steps.meta.outputs.releases }}

.github/workflows/test.yml

@@ -0,0 +1,30 @@
+name: Run Integration Tests
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  test:
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+
+      - name: Build Docker Image
+        env:
+          DOCKER_BUILDKIT: '1'
+        run: docker build . -t offen/docker-volume-backup:test
+
+      - name: Run Tests
+        working-directory: ./test
+        run: |
+          # Stop the buildx container so the tests can make assertions
+          # about the number of running containers
+          docker rm -f $(docker ps -aq)
+          export GPG_TTY=$(tty)
+          ./test.sh test

.golangci.yml

@@ -0,0 +1,8 @@
+linters:
+  # Enable specific linter
+  # https://golangci-lint.run/usage/linters/#enabled-by-default
+  enable:
+    - staticcheck
+    - govet
+output:
+  format: github-actions

Dockerfile

@@ -1,24 +1,21 @@
 # Copyright 2021 - Offen Authors <hioffen@posteo.de>
 # SPDX-License-Identifier: MPL-2.0
 
-FROM golang:1.18-alpine as builder
+FROM golang:1.21-alpine as builder
 
 WORKDIR /app
-COPY go.mod go.sum ./
+COPY . .
 RUN go mod download
-COPY cmd/backup ./cmd/backup/
 WORKDIR /app/cmd/backup
 RUN go build -o backup .
 
-FROM alpine:3.15
+FROM alpine:3.18
 
 WORKDIR /root
 
 RUN apk add --no-cache ca-certificates
 
 COPY --from=builder /app/cmd/backup/backup /usr/bin/backup
-
+COPY --chmod=755 ./entrypoint.sh /root/
-COPY ./entrypoint.sh /root/
-RUN chmod +x entrypoint.sh
 
 ENTRYPOINT ["/root/entrypoint.sh"]

README.md

@@ -4,23 +4,24 @@
 
 # docker-volume-backup
 
-Backup Docker volumes locally or to any S3 compatible storage.
+Backup Docker volumes locally or to any S3, WebDAV, Azure Blob Storage, Dropbox or SSH compatible storage.
 
 The [offen/docker-volume-backup](https://hub.docker.com/r/offen/docker-volume-backup) Docker image can be used as a lightweight (below 15MB) sidecar container to an existing Docker setup.
-It handles __recurring or one-off backups of Docker volumes__ to a __local directory__, __any S3 or WebDAV compatible storage (or any combination) and rotates away old backups__ if configured. It also supports __encrypting your backups using GPG__ and __sending notifications for failed backup runs__.
+It handles __recurring or one-off backups of Docker volumes__ to a __local directory__, __any S3, WebDAV, Azure Blob Storage, Dropbox or SSH compatible storage (or any combination) and rotates away old backups__ if configured. It also supports __encrypting your backups using GPG__ and __sending notifications for failed backup runs__.
 
 <!-- MarkdownTOC -->
 
 - [Quickstart](#quickstart)
   - [Recurring backups in a compose setup](#recurring-backups-in-a-compose-setup)
   - [One-off backups using Docker CLI](#one-off-backups-using-docker-cli)
+  - [Available image registries](#available-image-registries)
 - [Configuration reference](#configuration-reference)
 - [How to](#how-to)
   - [Stop containers during backup](#stop-containers-during-backup)
   - [Automatically pruning old backups](#automatically-pruning-old-backups)
   - [Send email notifications on failed backup runs](#send-email-notifications-on-failed-backup-runs)
   - [Customize notifications](#customize-notifications)
-  - [Run custom commands before / after backup](#run-custom-commands-before--after-backup)
+  - [Run custom commands during the backup lifecycle](#run-custom-commands-during-the-backup-lifecycle)
   - [Encrypting your backup using GPG](#encrypting-your-backup-using-gpg)
   - [Restoring a volume from a backup](#restoring-a-volume-from-a-backup)
   - [Set the timezone the container runs in](#set-the-timezone-the-container-runs-in)
@@ -28,14 +29,23 @@ It handles __recurring or one-off backups of Docker volumes__ to a __local direc
   - [Manually triggering a backup](#manually-triggering-a-backup)
   - [Update deprecated email configuration](#update-deprecated-email-configuration)
   - [Replace deprecated `BACKUP_FROM_SNAPSHOT` usage](#replace-deprecated-backup_from_snapshot-usage)
+  - [Replace deprecated `exec-pre` and `exec-post` labels](#replace-deprecated-exec-pre-and-exec-post-labels)
   - [Using a custom Docker host](#using-a-custom-docker-host)
+  - [Use with rootless Docker](#use-with-rootless-docker)
   - [Run multiple backup schedules in the same container](#run-multiple-backup-schedules-in-the-same-container)
   - [Define different retention schedules](#define-different-retention-schedules)
+  - [Use special characters in notification URLs](#use-special-characters-in-notification-urls)
+  - [Handle file uploads using third party tools](#handle-file-uploads-using-third-party-tools)
+  - [Setup Dropbox storage backend](#setup-dropbox-storage-backend)
 - [Recipes](#recipes)
   - [Backing up to AWS S3](#backing-up-to-aws-s3)
   - [Backing up to Filebase](#backing-up-to-filebase)
   - [Backing up to MinIO](#backing-up-to-minio)
+  - [Backing up to MinIO \(using Docker secrets\)](#backing-up-to-minio-using-docker-secrets)
   - [Backing up to WebDAV](#backing-up-to-webdav)
+  - [Backing up to SSH](#backing-up-to-ssh)
+  - [Backing up to Azure Blob Storage](#backing-up-to-azure-blob-storage)
+  - [Backing up to Dropbox](#backing-up-to-dropbox)
   - [Backing up locally](#backing-up-locally)
   - [Backing up to AWS S3 as well as locally](#backing-up-to-aws-s3-as-well-as-locally)
   - [Running on a custom cron schedule](#running-on-a-custom-cron-schedule)
@@ -114,6 +124,18 @@ docker run --rm \
 
 Alternatively, pass a `--env-file` in order to use a full config as described below.
 
+### Available image registries
+
+This Docker image is published to both Docker Hub and the GitHub container registry.
+Depending on your preferences and needs, you can reference both `offen/docker-volume-backup` as well as `ghcr.io/offen/docker-volume-backup`:
+
+```
+docker pull offen/docker-volume-backup:v2
+docker pull ghcr.io/offen/docker-volume-backup:v2
+```
+
+Documentation references Docker Hub, but all examples will work using ghcr.io just as well.
+
 ## Configuration reference
 
 Backup targets, schedule and retention are configured in environment variables.
@@ -128,13 +150,22 @@ You can populate below template according to your requirements and use it as you
 
 # BACKUP_CRON_EXPRESSION="0 2 * * *"
 
-# The name of the backup file including the `.tar.gz` extension.
+# The compression algorithm used in conjunction with tar.
+# Valid options are: "gz" (Gzip) and "zst" (Zstd).
+# Note that the selection affects the file extension.
+
+# BACKUP_COMPRESSION="gz"
+
+# The name of the backup file including the extension.
 # Format verbs will be replaced as in `strftime`. Omitting them
 # will result in the same filename for every backup run, which means previous
-# versions will be overwritten on subsequent runs. The default results
+# versions will be overwritten on subsequent runs.
-# in filenames like `backup-2021-08-29T04-00-00.tar.gz`.
+# Extension can be defined literally or via "{{ .Extension }}" template,
+# in which case it will become either "tar.gz" or "tar.zst" (depending
+# on your BACKUP_COMPRESSION setting).
+# The default results in filenames like: `backup-2021-08-29T04-00-00.tar.gz`.
 
-# BACKUP_FILENAME="backup-%Y-%m-%dT%H-%M-%S.tar.gz"
+# BACKUP_FILENAME="backup-%Y-%m-%dT%H-%M-%S.{{ .Extension }}"
 
 # Setting BACKUP_FILENAME_EXPAND to true allows for environment variable
 # placeholders in BACKUP_FILENAME, BACKUP_LATEST_SYMLINK and in
@@ -174,6 +205,15 @@ You can populate below template according to your requirements and use it as you
 
 # BACKUP_EXCLUDE_REGEXP="\.log$"
 
+# Exclude one or many storage backends from the pruning process.
+# E.g. with one backend excluded: BACKUP_SKIP_BACKENDS_FROM_PRUNE=s3
+# E.g. with multiple backends excluded: BACKUP_SKIP_BACKENDS_FROM_PRUNE=s3,webdav
+# Available backends are: S3, WebDAV, SSH, Local, Dropbox, Azure
+# Note: The name of the backends is case insensitive. 
+# Default: All backends get pruned.
+
+# BACKUP_SKIP_BACKENDS_FROM_PRUNE=
+
 ########### BACKUP STORAGE
 
 # The name of the remote bucket that should be used for storing backups. If
@@ -193,6 +233,14 @@ You can populate below template according to your requirements and use it as you
 # AWS_ACCESS_KEY_ID="<xxx>"
 # AWS_SECRET_ACCESS_KEY="<xxx>"
 
+# It is possible to provide the keys in files, allowing to hide the sensitive data.
+# These values have a higher priority than the ones above, meaning if both are set
+# the values from the files will be used.
+# This option is most useful with Docker [secrets](https://docs.docker.com/engine/swarm/secrets/).
+
+# AWS_ACCESS_KEY_ID_FILE="/path/to/file"
+# AWS_SECRET_ACCESS_KEY_FILE="/path/to/file"
+
 # Instead of providing static credentials, you can also use IAM instance profiles
 # or similar to provide authentication. Some possible configuration options on AWS:
 # - EC2: http://169.254.169.254
@@ -220,6 +268,27 @@ You can populate below template according to your requirements and use it as you
 
 # AWS_ENDPOINT_INSECURE="true"
 
+# If you wish to use self signed certificates your S3 server, you can pass
+# the location of a PEM encoded CA certificate and it will be used for
+# validating your certificates.
+# Alternatively, pass a PEM encoded string containing the certificate.
+
+# AWS_ENDPOINT_CA_CERT="/path/to/cert.pem"
+
+# Setting this variable will change the S3 storage class header.
+# Defaults to "STANDARD", you can set this value according to your needs.
+
+# AWS_STORAGE_CLASS="GLACIER"
+
+# Setting this variable will change the S3 default part size for the copy step.
+# This value is useful when you want to upload large files.
+# NB : While using Scaleway as S3 provider, be aware that the parts counter is set to 1.000.
+# While Minio uses a hard coded value to 10.000. As a workaround, try to set a higher value.
+# Defaults to "16" (MB) if unset (from minio), you can set this value according to your needs.
+# The unit is in MB and an integer.
+
+# AWS_PART_SIZE=16
+
 # You can also backup files to any WebDAV server:
 
 # The URL of the remote WebDAV server
@@ -245,6 +314,79 @@ You can populate below template according to your requirements and use it as you
 
 # WEBDAV_URL_INSECURE="true"
 
+# You can also backup files to any SSH server:
+
+# The URL of the remote SSH server
+
+# SSH_HOST_NAME="server.local"
+
+# The port of the remote SSH server
+# Optional variable default value is `22`
+
+# SSH_PORT=2222
+
+# The Directory to place the backups to on the SSH server.
+
+# SSH_REMOTE_PATH="/my/directory/"
+
+# The username for the SSH server
+
+# SSH_USER="user"
+
+# The password for the SSH server
+
+# SSH_PASSWORD="password"
+
+# The private key path in container for SSH server
+# Default value: /root/.ssh/id_rsa
+# If file is mounted to /root/.ssh/id_rsa path it will be used. Non-RSA keys will
+# also work.
+
+# SSH_IDENTITY_FILE="/root/.ssh/id_rsa"
+
+# The passphrase for the identity file
+
+# SSH_IDENTITY_PASSPHRASE="pass"
+
+# The credential's account name when using Azure Blob Storage. This has to be
+# set when using Azure Blob Storage.
+
+# AZURE_STORAGE_ACCOUNT_NAME="account-name"
+
+# The credential's primary account key when using Azure Blob Storage. If this
+# is not given, the command tries to fall back to using a managed identity.
+
+# AZURE_STORAGE_PRIMARY_ACCOUNT_KEY="<xxx>"
+
+# The container name when using Azure Blob Storage.
+
+# AZURE_STORAGE_CONTAINER_NAME="container-name"
+
+# The service endpoint when using Azure Blob Storage. This is a template that
+# can be passed the account name as shown in the default value below.
+
+# AZURE_STORAGE_ENDPOINT="https://{{ .AccountName }}.blob.core.windows.net/"
+
+# Absolute remote path in your Dropbox where the backups shall be stored.
+# Note: Use your app's subpath in Dropbox, if it doesn't have global access.
+# Consulte the README for further information.
+
+# DROPBOX_REMOTE_PATH="/my/directory"
+
+# Number of concurrent chunked uploads for Dropbox.
+# Values above 6 usually result in no enhancements.
+
+# DROPBOX_CONCURRENCY_LEVEL="6"
+
+# App key and app secret from your app created at https://www.dropbox.com/developers/apps/info
+
+# DROPBOX_APP_KEY=""
+# DROPBOX_APP_SECRET=""
+
+# Refresh token to request new short-lived tokens (OAuth2). Consult README to see how to get one.
+
+# DROPBOX_REFRESH_TOKEN=""
+
 # In addition to storing backups remotely, you can also keep local copies.
 # Pass a container-local path to store your backups if needed. You also need to
 # mount a local folder or Docker volume into that location (`/archive`
@@ -310,7 +452,7 @@ You can populate below template according to your requirements and use it as you
 
 # It is possible to define commands to be run in any container before and after
 # a backup is conducted. The commands themselves are defined in labels like
-# `docker-volume-backup.exec-pre=/bin/sh -c 'mysqldump [options] > dump.sql'.
+# `docker-volume-backup.archive-pre=/bin/sh -c 'mysqldump [options] > dump.sql'.
 # Several options exist for controlling this feature:
 
 # By default, any output of such a command is suppressed. If this value
@@ -331,7 +473,7 @@ You can populate below template according to your requirements and use it as you
 
 # Notifications (email, Slack, etc.) can be sent out when a backup run finishes.
 # Configuration is provided as a comma-separated list of URLs as consumed
-# by `shoutrrr`: https://containrrr.dev/shoutrrr/v0.5/services/overview/
+# by `shoutrrr`: https://containrrr.dev/shoutrrr/0.7/services/overview/
 # The content of such notifications can be customized. Dedicated documentation
 # on how to do this can be found in the README. When providing multiple URLs or
 # an URL that contains a comma, the values can be URL encoded to avoid ambiguities.
@@ -475,7 +617,7 @@ services:
 Notification backends other than email are also supported.
 Refer to the documentation of [shoutrrr][shoutrrr-docs] to find out about options and configuration.
 
-[shoutrrr-docs]: https://containrrr.dev/shoutrrr/v0.5/services/overview/
+[shoutrrr-docs]: https://containrrr.dev/shoutrrr/0.7/services/overview/
 
 ### Customize notifications
 
@@ -502,11 +644,16 @@ Overridable template names are: `title_success`, `body_success`, `title_failure`
 
 For a full list of available variables and functions, see [this page](https://github.com/offen/docker-volume-backup/blob/master/docs/NOTIFICATION-TEMPLATES.md).
 
-### Run custom commands before / after backup
+### Run custom commands during the backup lifecycle
 
 In certain scenarios it can be required to run specific commands before and after a backup is taken (e.g. dumping a database).
-When mounting the Docker socket into the `docker-volume-backup` container, you can define pre- and post-commands that will be run in the context of the target container.
+When mounting the Docker socket into the `docker-volume-backup` container, you can define pre- and post-commands that will be run in the context of the target container (it is also possible to run commands inside the `docker-volume-backup` container itself using this feature).
-Such commands are defined by specifying the command in a `docker-volume-backup.exec-[pre|post]` label.
+Such commands are defined by specifying the command in a `docker-volume-backup.[step]-[pre|post]` label where `step` can be any of the following phases of a backup lifecyle:
+
+- `archive` (the tar archive is created)
+- `process` (the tar archive is processed, e.g. encrypted - optional)
+- `copy` (the tar archive is copied to all configured storages)
+- `prune` (existing backups are pruned based on the defined ruleset - optional)
 
 Taking a database dump using `mysqldump` would look like this:
 
@@ -520,7 +667,7 @@ services:
     volumes:
       - backup_data:/tmp/backups
     labels:
-      - docker-volume-backup.exec-pre=/bin/sh -c 'mysqldump --all-databases > /backups/dump.sql'
+      - docker-volume-backup.archive-pre=/bin/sh -c 'mysqldump --all-databases > /backups/dump.sql'
 
 volumes:
   backup_data:
@@ -540,7 +687,7 @@ services:
     volumes:
       - backup_data:/tmp/backups
     labels:
-      - docker-volume-backup.exec-pre=/bin/sh -c 'mysqldump --all-databases > /tmp/volume/dump.sql'
+      - docker-volume-backup.archive-pre=/bin/sh -c 'mysqldump --all-databases > /tmp/volume/dump.sql'
       - docker-volume-backup.exec-label=database
 
   backup:
@@ -556,9 +703,27 @@ volumes:
 ```
 
 
-The backup procedure is guaranteed to wait for all `pre` commands to finish.
+The backup procedure is guaranteed to wait for all `pre` or `post` commands to finish before proceeding.
 However there are no guarantees about the order in which they are run, which could also happen concurrently.
 
+By default the backup command is executed by the user provided by the container's image.
+It is possible to specify a custom user that is used to run commands in dedicated labels with the format `docker-volume-backup.[step]-[pre|post].user`:
+
+```yml
+version: '3'
+
+services:
+  gitea:
+    image: gitea/gitea
+    volumes:
+      - backup_data:/tmp
+    labels:
+      - docker-volume-backup.archive-pre.user=git
+      - docker-volume-backup.archive-pre=/bin/bash -c 'cd /tmp; /usr/local/bin/gitea dump -c /data/gitea/conf/app.ini -R -f dump.zip'
+```
+
+Make sure the user exists and is present in `passwd` inside the target container.
+
 ### Encrypting your backup using GPG
 
 The image supports encrypting backups using GPG out of the box.
@@ -682,7 +847,7 @@ NOTIFICATION_URLS=smtp://me:secret@posteo.de:587/?fromAddress=no-reply@example.c
 ### Replace deprecated `BACKUP_FROM_SNAPSHOT` usage
 
 Starting with version 2.15.0, the `BACKUP_FROM_SNAPSHOT` feature has been deprecated.
-If you need to prepare your sources before the backup is taken, use `exec-pre`, `exec-post` and an intermediate volume:
+If you need to prepare your sources before the backup is taken, use `archive-pre`, `archive-post` and an intermediate volume:
 
 ```yml
 version: '3'
@@ -694,11 +859,11 @@ services:
       - data:/var/my_app
       - backup:/tmp/backup
     labels:
-      - docker-volume-backup.exec-pre=cp -r /var/my_app /tmp/backup/my-app
+      - docker-volume-backup.archive-pre=cp -r /var/my_app /tmp/backup/my-app
-      - docker-volume-backup.exec-post=rm -rf /tmp/backup/my-app
+      - docker-volume-backup.archive-post=rm -rf /tmp/backup/my-app
 
   backup:
-    image: offen/docker-volume-backup:latest
+    image: offen/docker-volume-backup:v2
     environment:
       BACKUP_SOURCES: /tmp/backup
     volumes:
@@ -710,6 +875,23 @@ volumes:
   backup:
 ```
 
+### Replace deprecated `exec-pre` and `exec-post` labels
+
+Version 2.19.0 introduced the option to run labeled commands at multiple points in time during the backup lifecycle.
+In order to be able to use more obvious terminology in the new labels, the existing `exec-pre` and `exec-post` labels have been deprecated.
+If you want to emulate the existing behavior, all you need to do is change `exec-pre` to `archive-pre` and `exec-post` to `archive-post`:
+
+```diff
+    labels:
+-     - docker-volume-backup.exec-pre=cp -r /var/my_app /tmp/backup/my-app
++     - docker-volume-backup.archive-pre=cp -r /var/my_app /tmp/backup/my-app
+-     - docker-volume-backup.exec-post=rm -rf /tmp/backup/my-app
++     - docker-volume-backup.archive-post=rm -rf /tmp/backup/my-app
+```
+
+The `EXEC_LABEL` setting and the `docker-volume-backup.exec-label` label stay as is.
+Check the additional documentation on running commands during the backup lifecycle to find out about further possibilities.
+
 ### Using a custom Docker host
 
 If you are interfacing with Docker via TCP, set `DOCKER_HOST` to the correct URL.
@@ -719,6 +901,23 @@ DOCKER_HOST=tcp://docker_socket_proxy:2375
 
 In case you are using a socket proxy, it must support `GET` and `POST` requests to the `/containers` endpoint. If you are using Docker Swarm, it must also support the `/services` endpoint. If you are using pre/post backup commands, it must also support the `/exec` endpoint.
 
+### Use with rootless Docker
+
+It's also possible to use this image with a [rootless Docker installation][rootless-docker].
+Instead of mounting `/var/run/docker.sock`, mount the user-specific socket into the container:
+
+```yml
+services:
+  backup:
+    image: offen/docker-volume-backup:v2
+    # ... configuration omitted
+    volumes:
+      - backup:/backup:ro
+      - /run/user/1000/docker.sock:/var/run/docker.sock:ro
+```
+
+[rootless-docker]: https://docs.docker.com/engine/security/rootless/
+
 ### Run multiple backup schedules in the same container
 
 Multiple backup schedules with different configuration can be configured by mounting an arbitrary number of configuration files (using the `.env` format) into `/etc/dockervolumebackup/conf.d`:
@@ -746,11 +945,30 @@ The exact order of schedules that use the same cron expression is not specified.
 In case you need your schedules to overlap, you need to create a dedicated container for each schedule instead.
 When changing the configuration, you currently need to manually restart the container for the changes to take effect.
 
+Set `BACKUP_SOURCES` for each config file to control which subset of volume mounts gets backed up:
+
+```yml
+# With a volume configuration like this:
+volumes:
+  - /var/run/docker.sock:/var/run/docker.sock:ro
+  - ./configuration:/etc/dockervolumebackup/conf.d
+  - app1_data:/backup/app1_data:ro
+  - app2_data:/backup/app2_data:ro
+```
+
+```ini
+# In the 1st config file:
+BACKUP_SOURCES=/backup/app1_data
+
+# In the 2nd config file:
+BACKUP_SOURCES=/backup/app2_data
+```
+
 ### Define different retention schedules
 
 If you want to manage backup retention on different schedules, the most straight forward approach is to define a dedicated configuration for retention rule using a different prefix in the `BACKUP_FILENAME` parameter and then run them on different cron schedules.
 
-For example, if you wanted to keep daily backups for 7 days, weekly backups for a month, and retain monthly backups forever, you could create three configuration files and mount them into `/etc/dockervolumebackup.d`:
+For example, if you wanted to keep daily backups for 7 days, weekly backups for a month, and retain monthly backups forever, you could create three configuration files and mount them into `/etc/dockervolumebackup/conf.d`:
 
 ```ini
 # 01daily.conf
@@ -779,6 +997,91 @@ BACKUP_CRON_EXPRESSION="0 4 1 * *"
 
 Note that while it's possible to define colliding cron schedules for each of these configurations, you might need to adjust the value for `LOCK_TIMEOUT` in case your backups are large and might take longer than an hour.
 
+### Use special characters in notification URLs
+
+The value given to `NOTIFICATION_URLS` is a comma separated list of URLs.
+If such a URL contains special characters (e.g. commas) it needs to be URL encoded.
+To get an encoded version of your URL, you can use the CLI tool provided by `shoutrrr` (which is the library used for sending notifications):
+
+```
+docker run --rm -ti containrrr/shoutrrr generate [service]
+```
+
+where service is any of the [supported services][shoutrrr-docs], e.g. for SMTP:
+
+```
+docker run --rm -ti containrrr/shoutrrr generate smtp
+```
+
+### Handle file uploads using third party tools
+
+If you want to use a non-supported storage backend, or want to use a third party (e.g. rsync, rclone) tool for file uploads, you can build a Docker image containing the required binaries off this one, and call through to these in lifecycle hooks.
+
+For example, if you wanted to use `rsync`, define your Docker image like this:
+
+```Dockerfile
+FROM offen/docker-volume-backup:v2
+
+RUN apk add rsync
+```
+
+Using this image, you can now omit configuring any of the supported storage backends, and instead define your own mechanism in a `docker-volume-backup.copy-post` label:
+
+```yml
+version: '3'
+
+services:
+  backup:
+    image: your-custom-image
+    restart: always
+    environment:
+      BACKUP_FILENAME: "daily-backup-%Y-%m-%dT%H-%M-%S.tar.gz"
+      BACKUP_CRON_EXPRESSION: "0 2 * * *"
+    labels:
+      - docker-volume-backup.copy-post=/bin/sh -c 'rsync $$COMMAND_RUNTIME_ARCHIVE_FILEPATH /destination'
+    volumes:
+      - app_data:/backup/app_data:ro
+      - /var/run/docker.sock:/var/run/docker.sock
+
+  # other services defined here ...
+volumes:
+  app_data:
+```
+
+
+Commands will be invoked with the filepath of the tar archive passed as `COMMAND_RUNTIME_BACKUP_FILEPATH`.
+
+### Setup Dropbox storage backend
+
+#### Auth-Setup:
+
+1. Create a new Dropbox App in the [App Console](https://www.dropbox.com/developers/apps)
+2. Open your new Dropbox App and set `DROPBOX_APP_KEY` and `DROPBOX_APP_SECRET` in your environment (e.g. docker-compose.yml) accordingly
+3. Click on `Permissions` in your app and make sure, that the following permissions are cranted (or more):
+  - `files.metadata.write`
+  - `files.metadata.read`
+  - `files.content.write`
+  - `files.content.read`
+4. Replace APPKEY in `https://www.dropbox.com/oauth2/authorize?client_id=APPKEY&token_access_type=offline&response_type=code` with the app key from step 2
+5. Visit the URL and confirm the access of your app. This gives you an `auth code` -> save it somewhere!
+6. Replace AUTHCODE, APPKEY, APPSECRET accordingly and perform the request:
+```
+curl https://api.dropbox.com/oauth2/token \
+    -d code=AUTHCODE \
+    -d grant_type=authorization_code \
+    -d client_id=APPKEY \
+    -d client_secret=APPSECRET
+```
+7. Execute the request. You will get a JSON formatted reply. Use the value of the `refresh_token` for the last environment variable `DROPBOX_REFRESH_TOKEN`
+8. You should now have `DROPBOX_APP_KEY`, `DROPBOX_APP_SECRET` and `DROPBOX_REFRESH_TOKEN` set. These don't expire.
+
+Note: Using the "Generated access token" in the app console is not supported, as it is only very short lived and therefore not suitable for an automatic backup solution. The refresh token handles this automatically - the setup procedure above is only needed once.
+
+#### Other parameters
+
+Important: If you chose `App folder` access during the creation of your Dropbox app in step 1 above, you can only write in the app's directory!
+This means, that `DROPBOX_REMOTE_PATH` must start with e.g. `/Apps/YOUR_APP_NAME` or `/Apps/YOUR_APP_NAME/some_sub_dir`
+
 ## Recipes
 
 This section lists configuration for some real-world use cases that you can mix and match according to your needs.
@@ -848,6 +1151,38 @@ volumes:
   data:
 ```
 
+
+### Backing up to MinIO (using Docker secrets)
+
+```yml
+version: '3'
+
+services:
+  # ... define other services using the `data` volume here
+  backup:
+    image: offen/docker-volume-backup:v2
+    environment:
+      AWS_ENDPOINT: minio.example.com
+      AWS_S3_BUCKET_NAME: backup-bucket
+      AWS_ACCESS_KEY_ID_FILE: /run/secrets/minio_access_key
+      AWS_SECRET_ACCESS_KEY_FILE: /run/secrets/minio_secret_key
+    volumes:
+      - data:/backup/my-app-backup:ro
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+    secrets:
+      - minio_access_key
+      - minio_secret_key
+
+volumes:
+  data:
+
+secrets:
+  minio_access_key:
+    # ... define how secret is accessed
+  minio_secret_key:
+    # ... define how secret is accessed
+```
+
 ### Backing up to WebDAV
 
 ```yml
@@ -870,6 +1205,74 @@ volumes:
   data:
 ```
 
+### Backing up to SSH
+
+```yml
+version: '3'
+
+services:
+  # ... define other services using the `data` volume here
+  backup:
+    image: offen/docker-volume-backup:v2
+    environment:
+      SSH_HOST_NAME: server.local
+      SSH_PORT: 2222
+      SSH_USER: user
+      SSH_REMOTE_PATH: /data
+    volumes:
+      - data:/backup/my-app-backup:ro
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+      - /path/to/private_key:/root/.ssh/id_rsa
+
+volumes:
+  data:
+```
+
+### Backing up to Azure Blob Storage
+
+```yml
+version: '3'
+
+services:
+  # ... define other services using the `data` volume here
+  backup:
+    image: offen/docker-volume-backup:v2
+    environment:
+      AZURE_STORAGE_CONTAINER_NAME: backup-container
+      AZURE_STORAGE_ACCOUNT_NAME: account-name
+      AZURE_STORAGE_PRIMARY_ACCOUNT_KEY: Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw==
+    volumes:
+      - data:/backup/my-app-backup:ro
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+
+volumes:
+  data:
+```
+
+### Backing up to Dropbox
+
+See [Dropbox Setup](#setup-dropbox-storage-backend) on how to get the appropriate environment values.
+
+```yml
+version: '3'
+
+services:
+  # ... define other services using the `data` volume here
+  backup:
+    image: offen/docker-volume-backup:v2
+    environment:
+      DROPBOX_REFRESH_TOKEN: REFRESH_KEY  # replace
+      DROPBOX_APP_KEY: APP_KEY  # replace
+      DROPBOX_APP_SECRET: APP_SECRET  # replace
+      DROPBOX_REMOTE_PATH: /Apps/my-test-app/some_subdir  # replace
+    volumes:
+      - data:/backup/my-app-backup:ro
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+
+volumes:
+  data:
+```
+
 ### Backing up locally
 
 ```yml
@@ -991,9 +1394,9 @@ services:
   database:
     image: mariadb:latest
     labels:
-      - docker-volume-backup.exec-pre=/bin/sh -c 'mysqldump -psecret --all-databases > /tmp/dumps/dump.sql'
+      - docker-volume-backup.archive-pre=/bin/sh -c 'mysqldump -psecret --all-databases > /tmp/dumps/dump.sql'
     volumes:
-      - app_data:/tmp/dumps
+      - data:/tmp/dumps
   backup:
     image: offen/docker-volume-backup:v2
     environment:

cmd/backup/archive.go

@@ -15,9 +15,11 @@ import (
 	"path"
 	"path/filepath"
 	"strings"
+
+	"github.com/klauspost/compress/zstd"
 )
 
-func createArchive(files []string, inputFilePath, outputFilePath string) error {
+func createArchive(files []string, inputFilePath, outputFilePath string, compression string) error {
 	inputFilePath = stripTrailingSlashes(inputFilePath)
 	inputFilePath, outputFilePath, err := makeAbsolute(inputFilePath, outputFilePath)
 	if err != nil {
@@ -27,7 +29,7 @@ func createArchive(files []string, inputFilePath, outputFilePath string) error {
 		return fmt.Errorf("createArchive: error creating output file path: %w", err)
 	}
 
-	if err := compress(files, outputFilePath, filepath.Dir(inputFilePath)); err != nil {
+	if err := compress(files, outputFilePath, filepath.Dir(inputFilePath), compression); err != nil {
 		return fmt.Errorf("createArchive: error creating archive: %w", err)
 	}
 
@@ -51,19 +53,31 @@ func makeAbsolute(inputFilePath, outputFilePath string) (string, string, error)
 	return inputFilePath, outputFilePath, err
 }
 
-func compress(paths []string, outFilePath, subPath string) error {
+func compress(paths []string, outFilePath, subPath string, algo string) error {
 	file, err := os.Create(outFilePath)
+	var compressWriter io.WriteCloser
 	if err != nil {
 		return fmt.Errorf("compress: error creating out file: %w", err)
 	}
 
 	prefix := path.Dir(outFilePath)
-	gzipWriter := gzip.NewWriter(file)
+	switch algo {
-	tarWriter := tar.NewWriter(gzipWriter)
+	case "gz":
+		compressWriter = gzip.NewWriter(file)
+	case "zst":
+		compressWriter, err = zstd.NewWriter(file)
+		if err != nil {
+			return fmt.Errorf("compress: zstd error: %w", err)
+		}
+	default:
+		return fmt.Errorf("compress: unsupported compression algorithm: %s", algo)
+	}
+
+	tarWriter := tar.NewWriter(compressWriter)
 
 	for _, p := range paths {
-		if err := writeTarGz(p, tarWriter, prefix); err != nil {
+		if err := writeTarball(p, tarWriter, prefix); err != nil {
-			return fmt.Errorf("compress error writing %s to archive: %w", p, err)
+			return fmt.Errorf("compress: error writing %s to archive: %w", p, err)
 		}
 	}
 
@@ -72,9 +86,9 @@ func compress(paths []string, outFilePath, subPath string) error {
 		return fmt.Errorf("compress: error closing tar writer: %w", err)
 	}
 
-	err = gzipWriter.Close()
+	err = compressWriter.Close()
 	if err != nil {
-		return fmt.Errorf("compress: error closing gzip writer: %w", err)
+		return fmt.Errorf("compress: error closing compression writer: %w", err)
 	}
 
 	err = file.Close()
@@ -85,10 +99,10 @@ func compress(paths []string, outFilePath, subPath string) error {
 	return nil
 }
 
-func writeTarGz(path string, tarWriter *tar.Writer, prefix string) error {
+func writeTarball(path string, tarWriter *tar.Writer, prefix string) error {
 	fileInfo, err := os.Lstat(path)
 	if err != nil {
-		return fmt.Errorf("writeTarGz: error getting file infor for %s: %w", path, err)
+		return fmt.Errorf("writeTarball: error getting file infor for %s: %w", path, err)
 	}
 
 	if fileInfo.Mode()&os.ModeSocket == os.ModeSocket {
@@ -99,19 +113,19 @@ func writeTarGz(path string, tarWriter *tar.Writer, prefix string) error {
 	if fileInfo.Mode()&os.ModeSymlink == os.ModeSymlink {
 		var err error
 		if link, err = os.Readlink(path); err != nil {
-			return fmt.Errorf("writeTarGz: error resolving symlink %s: %w", path, err)
+			return fmt.Errorf("writeTarball: error resolving symlink %s: %w", path, err)
 		}
 	}
 
 	header, err := tar.FileInfoHeader(fileInfo, link)
 	if err != nil {
-		return fmt.Errorf("writeTarGz: error getting file info header: %w", err)
+		return fmt.Errorf("writeTarball: error getting file info header: %w", err)
 	}
 	header.Name = strings.TrimPrefix(path, prefix)
 
 	err = tarWriter.WriteHeader(header)
 	if err != nil {
-		return fmt.Errorf("writeTarGz: error writing file info header: %w", err)
+		return fmt.Errorf("writeTarball: error writing file info header: %w", err)
 	}
 
 	if !fileInfo.Mode().IsRegular() {
@@ -120,13 +134,13 @@ func writeTarGz(path string, tarWriter *tar.Writer, prefix string) error {
 
 	file, err := os.Open(path)
 	if err != nil {
-		return fmt.Errorf("writeTarGz: error opening %s: %w", path, err)
+		return fmt.Errorf("writeTarball: error opening %s: %w", path, err)
 	}
 	defer file.Close()
 
 	_, err = io.Copy(tarWriter, file)
 	if err != nil {
-		return fmt.Errorf("writeTarGz: error copying %s to tar writer: %w", path, err)
+		return fmt.Errorf("writeTarball: error copying %s to tar writer: %w", path, err)
 	}
 
 	return nil

cmd/backup/config.go

@@ -4,50 +4,128 @@
 package main
 
 import (
+	"crypto/x509"
+	"encoding/pem"
 	"fmt"
+	"os"
 	"regexp"
+	"strconv"
 	"time"
 )
 
 // Config holds all configuration values that are expected to be set
 // by users.
 type Config struct {
-	BackupSources              string        `split_words:"true" default:"/backup"`
+	AwsS3BucketName               string          `split_words:"true"`
-	BackupFilename             string        `split_words:"true" default:"backup-%Y-%m-%dT%H-%M-%S.tar.gz"`
+	AwsS3Path                     string          `split_words:"true"`
-	BackupFilenameExpand       bool          `split_words:"true"`
+	AwsEndpoint                   string          `split_words:"true" default:"s3.amazonaws.com"`
-	BackupLatestSymlink        string        `split_words:"true"`
+	AwsEndpointProto              string          `split_words:"true" default:"https"`
-	BackupArchive              string        `split_words:"true" default:"/archive"`
+	AwsEndpointInsecure           bool            `split_words:"true"`
-	BackupRetentionDays        int32         `split_words:"true" default:"-1"`
+	AwsEndpointCACert             CertDecoder     `envconfig:"AWS_ENDPOINT_CA_CERT"`
-	BackupPruningLeeway        time.Duration `split_words:"true" default:"1m"`
+	AwsStorageClass               string          `split_words:"true"`
-	BackupPruningPrefix        string        `split_words:"true"`
+	AwsAccessKeyID                string          `envconfig:"AWS_ACCESS_KEY_ID"`
-	BackupStopContainerLabel   string        `split_words:"true" default:"true"`
+	AwsAccessKeyIDFile            string          `envconfig:"AWS_ACCESS_KEY_ID_FILE"`
-	BackupFromSnapshot         bool          `split_words:"true"`
+	AwsSecretAccessKey            string          `split_words:"true"`
-	BackupExcludeRegexp        RegexpDecoder `split_words:"true"`
+	AwsSecretAccessKeyFile        string          `split_words:"true"`
-	AwsS3BucketName            string        `split_words:"true"`
+	AwsIamRoleEndpoint            string          `split_words:"true"`
-	AwsS3Path                  string        `split_words:"true"`
+	AwsPartSize                   int64           `split_words:"true"`
-	AwsEndpoint                string        `split_words:"true" default:"s3.amazonaws.com"`
+	BackupCompression             CompressionType `split_words:"true" default:"gz"`
-	AwsEndpointProto           string        `split_words:"true" default:"https"`
+	BackupSources                 string          `split_words:"true" default:"/backup"`
-	AwsEndpointInsecure        bool          `split_words:"true"`
+	BackupFilename                string          `split_words:"true" default:"backup-%Y-%m-%dT%H-%M-%S.{{ .Extension }}"`
-	AwsAccessKeyID             string        `envconfig:"AWS_ACCESS_KEY_ID"`
+	BackupFilenameExpand          bool            `split_words:"true"`
-	AwsSecretAccessKey         string        `split_words:"true"`
+	BackupLatestSymlink           string          `split_words:"true"`
-	AwsIamRoleEndpoint         string        `split_words:"true"`
+	BackupArchive                 string          `split_words:"true" default:"/archive"`
-	GpgPassphrase              string        `split_words:"true"`
+	BackupRetentionDays           int32           `split_words:"true" default:"-1"`
-	NotificationURLs           []string      `envconfig:"NOTIFICATION_URLS"`
+	BackupPruningLeeway           time.Duration   `split_words:"true" default:"1m"`
-	NotificationLevel          string        `split_words:"true" default:"error"`
+	BackupPruningPrefix           string          `split_words:"true"`
-	EmailNotificationRecipient string        `split_words:"true"`
+	BackupStopContainerLabel      string          `split_words:"true" default:"true"`
-	EmailNotificationSender    string        `split_words:"true" default:"noreply@nohost"`
+	BackupFromSnapshot            bool            `split_words:"true"`
-	EmailSMTPHost              string        `envconfig:"EMAIL_SMTP_HOST"`
+	BackupExcludeRegexp           RegexpDecoder   `split_words:"true"`
-	EmailSMTPPort              int           `envconfig:"EMAIL_SMTP_PORT" default:"587"`
+	BackupSkipBackendsFromPrune   []string        `split_words:"true"`
-	EmailSMTPUsername          string        `envconfig:"EMAIL_SMTP_USERNAME"`
+	GpgPassphrase                 string          `split_words:"true"`
-	EmailSMTPPassword          string        `envconfig:"EMAIL_SMTP_PASSWORD"`
+	NotificationURLs              []string        `envconfig:"NOTIFICATION_URLS"`
-	WebdavUrl                  string        `split_words:"true"`
+	NotificationLevel             string          `split_words:"true" default:"error"`
-	WebdavUrlInsecure          bool          `split_words:"true"`
+	EmailNotificationRecipient    string          `split_words:"true"`
-	WebdavPath                 string        `split_words:"true" default:"/"`
+	EmailNotificationSender       string          `split_words:"true" default:"noreply@nohost"`
-	WebdavUsername             string        `split_words:"true"`
+	EmailSMTPHost                 string          `envconfig:"EMAIL_SMTP_HOST"`
-	WebdavPassword             string        `split_words:"true"`
+	EmailSMTPPort                 int             `envconfig:"EMAIL_SMTP_PORT" default:"587"`
-	ExecLabel                  string        `split_words:"true"`
+	EmailSMTPUsername             string          `envconfig:"EMAIL_SMTP_USERNAME"`
-	ExecForwardOutput          bool          `split_words:"true"`
+	EmailSMTPPassword             string          `envconfig:"EMAIL_SMTP_PASSWORD"`
-	LockTimeout                time.Duration `split_words:"true" default:"60m"`
+	WebdavUrl                     string          `split_words:"true"`
+	WebdavUrlInsecure             bool            `split_words:"true"`
+	WebdavPath                    string          `split_words:"true" default:"/"`
+	WebdavUsername                string          `split_words:"true"`
+	WebdavPassword                string          `split_words:"true"`
+	SSHHostName                   string          `split_words:"true"`
+	SSHPort                       string          `split_words:"true" default:"22"`
+	SSHUser                       string          `split_words:"true"`
+	SSHPassword                   string          `split_words:"true"`
+	SSHIdentityFile               string          `split_words:"true" default:"/root/.ssh/id_rsa"`
+	SSHIdentityPassphrase         string          `split_words:"true"`
+	SSHRemotePath                 string          `split_words:"true"`
+	ExecLabel                     string          `split_words:"true"`
+	ExecForwardOutput             bool            `split_words:"true"`
+	LockTimeout                   time.Duration   `split_words:"true" default:"60m"`
+	AzureStorageAccountName       string          `split_words:"true"`
+	AzureStoragePrimaryAccountKey string          `split_words:"true"`
+	AzureStorageContainerName     string          `split_words:"true"`
+	AzureStoragePath              string          `split_words:"true"`
+	AzureStorageEndpoint          string          `split_words:"true" default:"https://{{ .AccountName }}.blob.core.windows.net/"`
+	DropboxEndpoint               string          `split_words:"true" default:"https://api.dropbox.com/"`
+	DropboxOAuth2Endpoint         string          `envconfig:"DROPBOX_OAUTH2_ENDPOINT" default:"https://api.dropbox.com/"`
+	DropboxRefreshToken           string          `split_words:"true"`
+	DropboxAppKey                 string          `split_words:"true"`
+	DropboxAppSecret              string          `split_words:"true"`
+	DropboxRemotePath             string          `split_words:"true"`
+	DropboxConcurrencyLevel       NaturalNumber   `split_words:"true" default:"6"`
+}
+
+func (c *Config) resolveSecret(envVar string, secretPath string) (string, error) {
+	if secretPath == "" {
+		return envVar, nil
+	}
+	data, err := os.ReadFile(secretPath)
+	if err != nil {
+		return "", fmt.Errorf("resolveSecret: error reading secret path: %w", err)
+	}
+	return string(data), nil
+}
+
+type CompressionType string
+
+func (c *CompressionType) Decode(v string) error {
+	switch v {
+	case "gz", "zst":
+		*c = CompressionType(v)
+		return nil
+	default:
+		return fmt.Errorf("config: error decoding compression type %s", v)
+	}
+}
+
+func (c *CompressionType) String() string {
+	return string(*c)
+}
+
+type CertDecoder struct {
+	Cert *x509.Certificate
+}
+
+func (c *CertDecoder) Decode(v string) error {
+	if v == "" {
+		return nil
+	}
+	content, err := os.ReadFile(v)
+	if err != nil {
+		content = []byte(v)
+	}
+	block, _ := pem.Decode(content)
+	cert, err := x509.ParseCertificate(block.Bytes)
+	if err != nil {
+		return fmt.Errorf("config: error parsing certificate: %w", err)
+	}
+	*c = CertDecoder{Cert: cert}
+	return nil
 }
 
 type RegexpDecoder struct {
@@ -65,3 +143,21 @@ func (r *RegexpDecoder) Decode(v string) error {
 	*r = RegexpDecoder{Re: re}
 	return nil
 }
+
+type NaturalNumber int
+
+func (n *NaturalNumber) Decode(v string) error {
+	asInt, err := strconv.Atoi(v)
+	if err != nil {
+		return fmt.Errorf("config: error converting %s to int", v)
+	}
+	if asInt <= 0 {
+		return fmt.Errorf("config: expected a natural number, got %d", asInt)
+	}
+	*n = NaturalNumber(asInt)
+	return nil
+}
+
+func (n *NaturalNumber) Int() int {
+	return int(*n)
+}

cmd/backup/exec.go

@@ -10,7 +10,7 @@ import (
 	"bytes"
 	"context"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"os"
 	"strings"
 
@@ -21,12 +21,17 @@ import (
 	"golang.org/x/sync/errgroup"
 )
 
-func (s *script) exec(containerRef string, command string) ([]byte, []byte, error) {
+func (s *script) exec(containerRef string, command string, user string) ([]byte, []byte, error) {
 	args, _ := argv.Argv(command, nil, nil)
+	commandEnv := []string{
+		fmt.Sprintf("COMMAND_RUNTIME_ARCHIVE_FILEPATH=%s", s.file),
+	}
 	execID, err := s.cli.ContainerExecCreate(context.Background(), containerRef, types.ExecConfig{
 		Cmd:          args[0],
 		AttachStdin:  true,
 		AttachStderr: true,
+		Env:          commandEnv,
+		User:         user,
 	})
 	if err != nil {
 		return nil, nil, fmt.Errorf("exec: error creating container exec: %w", err)
@@ -46,19 +51,15 @@ func (s *script) exec(containerRef string, command string) ([]byte, []byte, erro
 		outputDone <- err
 	}()
 
-	select {
+	if <-outputDone != nil {
-	case err := <-outputDone:
+		return nil, nil, fmt.Errorf("exec: error demultiplexing output: %w", err)
-		if err != nil {
-			return nil, nil, fmt.Errorf("exec: error demultiplexing output: %w", err)
-		}
-		break
 	}
 
-	stdout, err := ioutil.ReadAll(&outBuf)
+	stdout, err := io.ReadAll(&outBuf)
 	if err != nil {
 		return nil, nil, fmt.Errorf("exec: error reading stdout: %w", err)
 	}
-	stderr, err := ioutil.ReadAll(&errBuf)
+	stderr, err := io.ReadAll(&errBuf)
 	if err != nil {
 		return nil, nil, fmt.Errorf("exec: error reading stderr: %w", err)
 	}
@@ -86,25 +87,77 @@ func (s *script) runLabeledCommands(label string) error {
 		})
 	}
 	containersWithCommand, err := s.cli.ContainerList(context.Background(), types.ContainerListOptions{
-		Quiet:   true,
 		Filters: filters.NewArgs(f...),
 	})
 	if err != nil {
 		return fmt.Errorf("runLabeledCommands: error querying for containers: %w", err)
 	}
 
+	var hasDeprecatedContainers bool
+	if label == "docker-volume-backup.archive-pre" {
+		f[0] = filters.KeyValuePair{
+			Key:   "label",
+			Value: "docker-volume-backup.exec-pre",
+		}
+		deprecatedContainers, err := s.cli.ContainerList(context.Background(), types.ContainerListOptions{
+			Filters: filters.NewArgs(f...),
+		})
+		if err != nil {
+			return fmt.Errorf("runLabeledCommands: error querying for containers: %w", err)
+		}
+		if len(deprecatedContainers) != 0 {
+			hasDeprecatedContainers = true
+			containersWithCommand = append(containersWithCommand, deprecatedContainers...)
+		}
+	}
+
+	if label == "docker-volume-backup.archive-post" {
+		f[0] = filters.KeyValuePair{
+			Key:   "label",
+			Value: "docker-volume-backup.exec-post",
+		}
+		deprecatedContainers, err := s.cli.ContainerList(context.Background(), types.ContainerListOptions{
+			Filters: filters.NewArgs(f...),
+		})
+		if err != nil {
+			return fmt.Errorf("runLabeledCommands: error querying for containers: %w", err)
+		}
+		if len(deprecatedContainers) != 0 {
+			hasDeprecatedContainers = true
+			containersWithCommand = append(containersWithCommand, deprecatedContainers...)
+		}
+	}
+
 	if len(containersWithCommand) == 0 {
 		return nil
 	}
 
+	if hasDeprecatedContainers {
+		s.logger.Warn(
+			"Using `docker-volume-backup.exec-pre` and `docker-volume-backup.exec-post` labels has been deprecated and will be removed in the next major version.",
+		)
+		s.logger.Warn(
+			"Please use other `-pre` and `-post` labels instead. Refer to the README for an upgrade guide.",
+		)
+	}
+
 	g := new(errgroup.Group)
 
 	for _, container := range containersWithCommand {
 		c := container
 		g.Go(func() error {
-			cmd, _ := c.Labels[label]
+			cmd, ok := c.Labels[label]
-			s.logger.Infof("Running %s command %s for container %s", label, cmd, strings.TrimPrefix(c.Names[0], "/"))
+			if !ok && label == "docker-volume-backup.archive-pre" {
-			stdout, stderr, err := s.exec(c.ID, cmd)
+				cmd = c.Labels["docker-volume-backup.exec-pre"]
+			} else if !ok && label == "docker-volume-backup.archive-post" {
+				cmd = c.Labels["docker-volume-backup.exec-post"]
+			}
+
+			userLabelName := fmt.Sprintf("%s.user", label)
+			user := c.Labels[userLabelName]
+
+			s.logger.Info(fmt.Sprintf("Running %s command %s for container %s", label, cmd, strings.TrimPrefix(c.Names[0], "/")))
+			stdout, stderr, err := s.exec(c.ID, cmd, user)
 			if s.c.ExecForwardOutput {
 				os.Stderr.Write(stderr)
 				os.Stdout.Write(stdout)
@@ -121,3 +174,27 @@ func (s *script) runLabeledCommands(label string) error {
 	}
 	return nil
 }
+
+type lifecyclePhase string
+
+const (
+	lifecyclePhaseArchive lifecyclePhase = "archive"
+	lifecyclePhaseProcess lifecyclePhase = "process"
+	lifecyclePhaseCopy    lifecyclePhase = "copy"
+	lifecyclePhasePrune   lifecyclePhase = "prune"
+)
+
+func (s *script) withLabeledCommands(step lifecyclePhase, cb func() error) func() error {
+	if s.cli == nil {
+		return cb
+	}
+	return func() error {
+		if err := s.runLabeledCommands(fmt.Sprintf("docker-volume-backup.%s-pre", step)); err != nil {
+			return fmt.Errorf("withLabeledCommands: %s: error running pre commands: %w", step, err)
+		}
+		defer func() {
+			s.must(s.runLabeledCommands(fmt.Sprintf("docker-volume-backup.%s-post", step)))
+		}()
+		return cb()
+	}
+}

cmd/backup/hooks.go

@@ -4,6 +4,7 @@
 package main
 
 import (
+	"errors"
 	"fmt"
 	"sort"
 )
@@ -50,7 +51,7 @@ func (s *script) runHooks(err error) error {
 		}
 	}
 	if len(actionErrors) != 0 {
-		return join(actionErrors...)
+		return errors.Join(actionErrors...)
 	}
 	return nil
 }

cmd/backup/lock.go

@@ -18,7 +18,7 @@ import (
 func (s *script) lock(lockfile string) (func() error, error) {
 	start := time.Now()
 	defer func() {
-		s.stats.LockedTime = time.Now().Sub(start)
+		s.stats.LockedTime = time.Since(start)
 	}()
 
 	retry := time.NewTicker(5 * time.Second)
@@ -31,7 +31,7 @@ func (s *script) lock(lockfile string) (func() error, error) {
 	for {
 		acquired, err := fileLock.TryLock()
 		if err != nil {
-			return noop, fmt.Errorf("lock: error trying lock: %w", err)
+			return noop, fmt.Errorf("lock: error trying to lock: %w", err)
 		}
 		if acquired {
 			if s.encounteredLock {
@@ -41,9 +41,11 @@ func (s *script) lock(lockfile string) (func() error, error) {
 		}
 
 		if !s.encounteredLock {
-			s.logger.Infof(
+			s.logger.Info(
-				"Exclusive lock was not available on first attempt. Will retry until it becomes available or the timeout of %s is exceeded.",
+				fmt.Sprintf(
-				s.c.LockTimeout,
+					"Exclusive lock was not available on first attempt. Will retry until it becomes available or the timeout of %s is exceeded.",
+					s.c.LockTimeout,
+				),
 			)
 			s.encounteredLock = true
 		}

cmd/backup/main.go

@@ -4,6 +4,7 @@
 package main
 
 import (
+	"fmt"
 	"os"
 )
 
@@ -14,14 +15,16 @@ func main() {
 	}
 
 	unlock, err := s.lock("/var/lock/dockervolumebackup.lock")
-	defer unlock()
+	defer s.must(unlock())
 	s.must(err)
 
 	defer func() {
 		if pArg := recover(); pArg != nil {
 			if err, ok := pArg.(error); ok {
 				if hookErr := s.runHooks(err); hookErr != nil {
-					s.logger.Errorf("An error occurred calling the registered hooks: %s", hookErr)
+					s.logger.Error(
+						fmt.Sprintf("An error occurred calling the registered hooks: %s", hookErr),
+					)
 				}
 				os.Exit(1)
 			}
@@ -29,23 +32,18 @@ func main() {
 		}
 
 		if err := s.runHooks(nil); err != nil {
-			s.logger.Errorf(
+			s.logger.Error(
-				"Backup procedure ran successfully, but an error ocurred calling the registered hooks: %v",
+				fmt.Sprintf(
-				err,
+					"Backup procedure ran successfully, but an error ocurred calling the registered hooks: %v",
+					err,
+				),
 			)
 			os.Exit(1)
 		}
 		s.logger.Info("Finished running backup tasks.")
 	}()
 
-	s.must(func() error {
+	s.must(s.withLabeledCommands(lifecyclePhaseArchive, func() error {
-		runPostCommands, err := s.runCommands()
-		defer func() {
-			s.must(runPostCommands())
-		}()
-		if err != nil {
-			return err
-		}
 		restartContainers, err := s.stopContainers()
 		// The mechanism for restarting containers is not using hooks as it
 		// should happen as soon as possible (i.e. before uploading backups or
@@ -56,10 +54,10 @@ func main() {
 		if err != nil {
 			return err
 		}
-		return s.takeBackup()
+		return s.createArchive()
-	}())
+	})())
 
-	s.must(s.encryptBackup())
+	s.must(s.withLabeledCommands(lifecyclePhaseProcess, s.encryptArchive)())
-	s.must(s.copyBackup())
+	s.must(s.withLabeledCommands(lifecyclePhaseCopy, s.copyArchive)())
-	s.must(s.pruneBackups())
+	s.must(s.withLabeledCommands(lifecyclePhasePrune, s.pruneBackups)())
 }

cmd/backup/notifications.go

@@ -6,7 +6,9 @@ package main
 import (
 	"bytes"
 	_ "embed"
+	"errors"
 	"fmt"
+	"os"
 	"text/template"
 	"time"
 
@@ -34,16 +36,16 @@ func (s *script) notify(titleTemplate string, bodyTemplate string, err error) er
 
 	titleBuf := &bytes.Buffer{}
 	if err := s.template.ExecuteTemplate(titleBuf, titleTemplate, params); err != nil {
-		return fmt.Errorf("notifyFailure: error executing %s template: %w", titleTemplate, err)
+		return fmt.Errorf("notify: error executing %s template: %w", titleTemplate, err)
 	}
 
 	bodyBuf := &bytes.Buffer{}
 	if err := s.template.ExecuteTemplate(bodyBuf, bodyTemplate, params); err != nil {
-		return fmt.Errorf("notifyFailure: error executing %s template: %w", bodyTemplate, err)
+		return fmt.Errorf("notify: error executing %s template: %w", bodyTemplate, err)
 	}
 
 	if err := s.sendNotification(titleBuf.String(), bodyBuf.String()); err != nil {
-		return fmt.Errorf("notifyFailure: error notifying: %w", err)
+		return fmt.Errorf("notify: error notifying: %w", err)
 	}
 	return nil
 }
@@ -67,7 +69,7 @@ func (s *script) sendNotification(title, body string) error {
 		}
 	}
 	if len(errs) != 0 {
-		return fmt.Errorf("sendNotification: error sending message: %w", join(errs...))
+		return fmt.Errorf("sendNotification: error sending message: %w", errors.Join(errs...))
 	}
 	return nil
 }
@@ -82,6 +84,7 @@ var templateHelpers = template.FuncMap{
 	"formatBytesBin": func(bytes uint64) string {
 		return formatBytes(bytes, false)
 	},
+	"env": os.Getenv,
 }
 
 // formatBytes converts an amount of bytes in a human-readable representation

cmd/backup/script.go

@@ -4,46 +4,53 @@
 package main
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"fmt"
 	"io"
 	"io/fs"
-	"net/http"
+	"log/slog"
 	"os"
 	"path"
 	"path/filepath"
+	"slices"
 	"strings"
 	"text/template"
 	"time"
 
+	"github.com/offen/docker-volume-backup/internal/storage"
+	"github.com/offen/docker-volume-backup/internal/storage/azure"
+	"github.com/offen/docker-volume-backup/internal/storage/dropbox"
+	"github.com/offen/docker-volume-backup/internal/storage/local"
+	"github.com/offen/docker-volume-backup/internal/storage/s3"
+	"github.com/offen/docker-volume-backup/internal/storage/ssh"
+	"github.com/offen/docker-volume-backup/internal/storage/webdav"
+
+	"github.com/ProtonMail/go-crypto/openpgp"
 	"github.com/containrrr/shoutrrr"
 	"github.com/containrrr/shoutrrr/pkg/router"
 	"github.com/docker/docker/api/types"
+	ctr "github.com/docker/docker/api/types/container"
 	"github.com/docker/docker/api/types/filters"
 	"github.com/docker/docker/api/types/swarm"
 	"github.com/docker/docker/client"
 	"github.com/kelseyhightower/envconfig"
 	"github.com/leekchan/timeutil"
-	"github.com/minio/minio-go/v7"
-	"github.com/minio/minio-go/v7/pkg/credentials"
 	"github.com/otiai10/copy"
-	"github.com/sirupsen/logrus"
+	"golang.org/x/sync/errgroup"
-	"github.com/studio-b12/gowebdav"
-	"golang.org/x/crypto/openpgp"
 )
 
 // script holds all the stateful information required to orchestrate a
 // single backup run.
 type script struct {
-	cli          *client.Client
+	cli       *client.Client
-	minioClient  *minio.Client
+	storages  []storage.Backend
-	webdavClient *gowebdav.Client
+	logger    *slog.Logger
-	logger       *logrus.Logger
+	sender    *router.ServiceRouter
-	sender       *router.ServiceRouter
+	template  *template.Template
-	template     *template.Template
+	hooks     []hook
-	hooks        []hook
+	hookLevel hookLevel
-	hookLevel    hookLevel
 
 	file  string
 	stats *Stats
@@ -60,17 +67,19 @@ type script struct {
 func newScript() (*script, error) {
 	stdOut, logBuffer := buffer(os.Stdout)
 	s := &script{
-		c: &Config{},
+		c:      &Config{},
-		logger: &logrus.Logger{
+		logger: slog.New(slog.NewTextHandler(stdOut, nil)),
-			Out:       stdOut,
-			Formatter: new(logrus.TextFormatter),
-			Hooks:     make(logrus.LevelHooks),
-			Level:     logrus.InfoLevel,
-		},
 		stats: &Stats{
 			StartTime: time.Now(),
 			LogOutput: logBuffer,
-			Storages:  StoragesStats{},
+			Storages: map[string]StorageStats{
+				"S3":      {},
+				"WebDAV":  {},
+				"SSH":     {},
+				"Local":   {},
+				"Azure":   {},
+				"Dropbox": {},
+			},
 		},
 	}
 
@@ -85,6 +94,20 @@ func newScript() (*script, error) {
 	}
 
 	s.file = path.Join("/tmp", s.c.BackupFilename)
+
+	tmplFileName, tErr := template.New("extension").Parse(s.file)
+	if tErr != nil {
+		return nil, fmt.Errorf("newScript: unable to parse backup file extension template: %w", tErr)
+	}
+
+	var bf bytes.Buffer
+	if tErr := tmplFileName.Execute(&bf, map[string]string{
+		"Extension": fmt.Sprintf("tar.%s", s.c.BackupCompression),
+	}); tErr != nil {
+		return nil, fmt.Errorf("newScript: error executing backup file extension template: %w", tErr)
+	}
+	s.file = bf.String()
+
 	if s.c.BackupFilenameExpand {
 		s.file = os.ExpandEnv(s.file)
 		s.c.BackupLatestSymlink = os.ExpandEnv(s.c.BackupLatestSymlink)
@@ -102,61 +125,117 @@ func newScript() (*script, error) {
 		s.cli = cli
 	}
 
+	logFunc := func(logType storage.LogLevel, context string, msg string, params ...any) {
+		switch logType {
+		case storage.LogLevelWarning:
+			s.logger.Warn(fmt.Sprintf(msg, params...), "storage", context)
+		case storage.LogLevelError:
+			s.logger.Error(fmt.Sprintf(msg, params...), "storage", context)
+		default:
+			s.logger.Info(fmt.Sprintf(msg, params...), "storage", context)
+		}
+	}
+
 	if s.c.AwsS3BucketName != "" {
-		var creds *credentials.Credentials
+		accessKeyID, err := s.c.resolveSecret(s.c.AwsAccessKeyID, s.c.AwsAccessKeyIDFile)
-		if s.c.AwsAccessKeyID != "" && s.c.AwsSecretAccessKey != "" {
-			creds = credentials.NewStaticV4(
-				s.c.AwsAccessKeyID,
-				s.c.AwsSecretAccessKey,
-				"",
-			)
-		} else if s.c.AwsIamRoleEndpoint != "" {
-			creds = credentials.NewIAM(s.c.AwsIamRoleEndpoint)
-		} else {
-			return nil, errors.New("newScript: AWS_S3_BUCKET_NAME is defined, but no credentials were provided")
-		}
-
-		options := minio.Options{
-			Creds:  creds,
-			Secure: s.c.AwsEndpointProto == "https",
-		}
-
-		if s.c.AwsEndpointInsecure {
-			if !options.Secure {
-				return nil, errors.New("newScript: AWS_ENDPOINT_INSECURE = true is only meaningful for https")
-			}
-
-			transport, err := minio.DefaultTransport(true)
-			if err != nil {
-				return nil, fmt.Errorf("newScript: failed to create default minio transport")
-			}
-			transport.TLSClientConfig.InsecureSkipVerify = true
-			options.Transport = transport
-		}
-
-		mc, err := minio.New(s.c.AwsEndpoint, &options)
 		if err != nil {
-			return nil, fmt.Errorf("newScript: error setting up minio client: %w", err)
+			return nil, fmt.Errorf("newScript: error resolving AwsAccessKeyID: %w", err)
+		}
+		secretAccessKey, err := s.c.resolveSecret(s.c.AwsSecretAccessKey, s.c.AwsSecretAccessKeyFile)
+		if err != nil {
+			return nil, fmt.Errorf("newScript: error resolving AwsSecretAccessKey: %w", err)
+		}
+		s3Config := s3.Config{
+			Endpoint:         s.c.AwsEndpoint,
+			AccessKeyID:      accessKeyID,
+			SecretAccessKey:  secretAccessKey,
+			IamRoleEndpoint:  s.c.AwsIamRoleEndpoint,
+			EndpointProto:    s.c.AwsEndpointProto,
+			EndpointInsecure: s.c.AwsEndpointInsecure,
+			RemotePath:       s.c.AwsS3Path,
+			BucketName:       s.c.AwsS3BucketName,
+			StorageClass:     s.c.AwsStorageClass,
+			CACert:           s.c.AwsEndpointCACert.Cert,
+			PartSize:         s.c.AwsPartSize,
+		}
+		if s3Backend, err := s3.NewStorageBackend(s3Config, logFunc); err != nil {
+			return nil, fmt.Errorf("newScript: error creating s3 storage backend: %w", err)
+		} else {
+			s.storages = append(s.storages, s3Backend)
 		}
-		s.minioClient = mc
 	}
 
 	if s.c.WebdavUrl != "" {
-		if s.c.WebdavUsername == "" || s.c.WebdavPassword == "" {
+		webDavConfig := webdav.Config{
-			return nil, errors.New("newScript: WEBDAV_URL is defined, but no credentials were provided")
+			URL:         s.c.WebdavUrl,
-		} else {
+			URLInsecure: s.c.WebdavUrlInsecure,
-			webdavClient := gowebdav.NewClient(s.c.WebdavUrl, s.c.WebdavUsername, s.c.WebdavPassword)
+			Username:    s.c.WebdavUsername,
-			s.webdavClient = webdavClient
+			Password:    s.c.WebdavPassword,
-			if s.c.WebdavUrlInsecure {
+			RemotePath:  s.c.WebdavPath,
-				defaultTransport, ok := http.DefaultTransport.(*http.Transport)
-				if !ok {
-					return nil, errors.New("newScript: unexpected error when asserting type for http.DefaultTransport")
-				}
-				webdavTransport := defaultTransport.Clone()
-				webdavTransport.TLSClientConfig.InsecureSkipVerify = s.c.WebdavUrlInsecure
-				s.webdavClient.SetTransport(webdavTransport)
-			}
 		}
+		if webdavBackend, err := webdav.NewStorageBackend(webDavConfig, logFunc); err != nil {
+			return nil, fmt.Errorf("newScript: error creating webdav storage backend: %w", err)
+		} else {
+			s.storages = append(s.storages, webdavBackend)
+		}
+	}
+
+	if s.c.SSHHostName != "" {
+		sshConfig := ssh.Config{
+			HostName:           s.c.SSHHostName,
+			Port:               s.c.SSHPort,
+			User:               s.c.SSHUser,
+			Password:           s.c.SSHPassword,
+			IdentityFile:       s.c.SSHIdentityFile,
+			IdentityPassphrase: s.c.SSHIdentityPassphrase,
+			RemotePath:         s.c.SSHRemotePath,
+		}
+		if sshBackend, err := ssh.NewStorageBackend(sshConfig, logFunc); err != nil {
+			return nil, fmt.Errorf("newScript: error creating ssh storage backend: %w", err)
+		} else {
+			s.storages = append(s.storages, sshBackend)
+		}
+	}
+
+	if _, err := os.Stat(s.c.BackupArchive); !os.IsNotExist(err) {
+		localConfig := local.Config{
+			ArchivePath:   s.c.BackupArchive,
+			LatestSymlink: s.c.BackupLatestSymlink,
+		}
+		localBackend := local.NewStorageBackend(localConfig, logFunc)
+		s.storages = append(s.storages, localBackend)
+	}
+
+	if s.c.AzureStorageAccountName != "" {
+		azureConfig := azure.Config{
+			ContainerName:     s.c.AzureStorageContainerName,
+			AccountName:       s.c.AzureStorageAccountName,
+			PrimaryAccountKey: s.c.AzureStoragePrimaryAccountKey,
+			Endpoint:          s.c.AzureStorageEndpoint,
+			RemotePath:        s.c.AzureStoragePath,
+		}
+		azureBackend, err := azure.NewStorageBackend(azureConfig, logFunc)
+		if err != nil {
+			return nil, fmt.Errorf("newScript: error creating azure storage backend: %w", err)
+		}
+		s.storages = append(s.storages, azureBackend)
+	}
+
+	if s.c.DropboxRefreshToken != "" && s.c.DropboxAppKey != "" && s.c.DropboxAppSecret != "" {
+		dropboxConfig := dropbox.Config{
+			Endpoint:         s.c.DropboxEndpoint,
+			OAuth2Endpoint:   s.c.DropboxOAuth2Endpoint,
+			RefreshToken:     s.c.DropboxRefreshToken,
+			AppKey:           s.c.DropboxAppKey,
+			AppSecret:        s.c.DropboxAppSecret,
+			RemotePath:       s.c.DropboxRemotePath,
+			ConcurrencyLevel: s.c.DropboxConcurrencyLevel.Int(),
+		}
+		dropboxBackend, err := dropbox.NewStorageBackend(dropboxConfig, logFunc)
+		if err != nil {
+			return nil, fmt.Errorf("newScript: error creating dropbox storage backend: %w", err)
+		}
+		s.storages = append(s.storages, dropboxBackend)
 	}
 
 	if s.c.EmailNotificationRecipient != "" {
@@ -225,22 +304,6 @@ func newScript() (*script, error) {
 	return s, nil
 }
 
-func (s *script) runCommands() (func() error, error) {
-	if s.cli == nil {
-		return noop, nil
-	}
-
-	if err := s.runLabeledCommands("docker-volume-backup.exec-pre"); err != nil {
-		return noop, fmt.Errorf("runCommands: error running pre commands: %w", err)
-	}
-	return func() error {
-		if err := s.runLabeledCommands("docker-volume-backup.exec-post"); err != nil {
-			return fmt.Errorf("runCommands: error running post commands: %w", err)
-		}
-		return nil
-	}, nil
-}
-
 // stopContainers stops all Docker containers that are marked as to being
 // stopped during the backup and returns a function that can be called to
 // restart everything that has been stopped.
@@ -249,11 +312,9 @@ func (s *script) stopContainers() (func() error, error) {
 		return noop, nil
 	}
 
-	allContainers, err := s.cli.ContainerList(context.Background(), types.ContainerListOptions{
+	allContainers, err := s.cli.ContainerList(context.Background(), types.ContainerListOptions{})
-		Quiet: true,
-	})
 	if err != nil {
-		return noop, fmt.Errorf("stopContainersAndRun: error querying for containers: %w", err)
+		return noop, fmt.Errorf("stopContainers: error querying for containers: %w", err)
 	}
 
 	containerLabel := fmt.Sprintf(
@@ -261,7 +322,6 @@ func (s *script) stopContainers() (func() error, error) {
 		s.c.BackupStopContainerLabel,
 	)
 	containersToStop, err := s.cli.ContainerList(context.Background(), types.ContainerListOptions{
-		Quiet: true,
 		Filters: filters.NewArgs(filters.KeyValuePair{
 			Key:   "label",
 			Value: containerLabel,
@@ -269,24 +329,26 @@ func (s *script) stopContainers() (func() error, error) {
 	})
 
 	if err != nil {
-		return noop, fmt.Errorf("stopContainersAndRun: error querying for containers to stop: %w", err)
+		return noop, fmt.Errorf("stopContainers: error querying for containers to stop: %w", err)
 	}
 
 	if len(containersToStop) == 0 {
 		return noop, nil
 	}
 
-	s.logger.Infof(
+	s.logger.Info(
-		"Stopping %d container(s) labeled `%s` out of %d running container(s).",
+		fmt.Sprintf(
-		len(containersToStop),
+			"Stopping %d container(s) labeled `%s` out of %d running container(s).",
-		containerLabel,
+			len(containersToStop),
-		len(allContainers),
+			containerLabel,
+			len(allContainers),
+		),
 	)
 
 	var stoppedContainers []types.Container
 	var stopErrors []error
 	for _, container := range containersToStop {
-		if err := s.cli.ContainerStop(context.Background(), container.ID, nil); err != nil {
+		if err := s.cli.ContainerStop(context.Background(), container.ID, ctr.StopOptions{}); err != nil {
 			stopErrors = append(stopErrors, err)
 		} else {
 			stoppedContainers = append(stoppedContainers, container)
@@ -296,9 +358,9 @@ func (s *script) stopContainers() (func() error, error) {
 	var stopError error
 	if len(stopErrors) != 0 {
 		stopError = fmt.Errorf(
-			"stopContainersAndRun: %d error(s) stopping containers: %w",
+			"stopContainers: %d error(s) stopping containers: %w",
 			len(stopErrors),
-			join(stopErrors...),
+			errors.Join(stopErrors...),
 		)
 	}
 
@@ -333,9 +395,9 @@ func (s *script) stopContainers() (func() error, error) {
 					}
 				}
 				if serviceMatch.ID == "" {
-					return fmt.Errorf("stopContainersAndRun: couldn't find service with name %s", serviceName)
+					return fmt.Errorf("stopContainers: couldn't find service with name %s", serviceName)
 				}
-				serviceMatch.Spec.TaskTemplate.ForceUpdate = 1
+				serviceMatch.Spec.TaskTemplate.ForceUpdate += 1
 				if _, err := s.cli.ServiceUpdate(
 					context.Background(), serviceMatch.ID,
 					serviceMatch.Version, serviceMatch.Spec, types.ServiceUpdateOptions{},
@@ -347,22 +409,24 @@ func (s *script) stopContainers() (func() error, error) {
 
 		if len(restartErrors) != 0 {
 			return fmt.Errorf(
-				"stopContainersAndRun: %d error(s) restarting containers and services: %w",
+				"stopContainers: %d error(s) restarting containers and services: %w",
 				len(restartErrors),
-				join(restartErrors...),
+				errors.Join(restartErrors...),
 			)
 		}
-		s.logger.Infof(
+		s.logger.Info(
-			"Restarted %d container(s) and the matching service(s).",
+			fmt.Sprintf(
-			len(stoppedContainers),
+				"Restarted %d container(s) and the matching service(s).",
+				len(stoppedContainers),
+			),
 		)
 		return nil
 	}, stopError
 }
 
-// takeBackup creates a tar archive of the configured backup location and
+// createArchive creates a tar archive of the configured backup location and
 // saves it to disk.
-func (s *script) takeBackup() error {
+func (s *script) createArchive() error {
 	backupSources := s.c.BackupSources
 
 	if s.c.BackupFromSnapshot {
@@ -370,38 +434,44 @@ func (s *script) takeBackup() error {
 			"Using BACKUP_FROM_SNAPSHOT has been deprecated and will be removed in the next major version.",
 		)
 		s.logger.Warn(
-			"Please use `exec-pre` and `exec-post` commands to prepare your backup sources. Refer to the README for an upgrade guide.",
+			"Please use `archive-pre` and `archive-post` commands to prepare your backup sources. Refer to the README for an upgrade guide.",
 		)
 		backupSources = filepath.Join("/tmp", s.c.BackupSources)
 		// copy before compressing guard against a situation where backup folder's content are still growing.
 		s.registerHook(hookLevelPlumbing, func(error) error {
 			if err := remove(backupSources); err != nil {
-				return fmt.Errorf("takeBackup: error removing snapshot: %w", err)
+				return fmt.Errorf("createArchive: error removing snapshot: %w", err)
 			}
-			s.logger.Infof("Removed snapshot `%s`.", backupSources)
+			s.logger.Info(
+				fmt.Sprintf("Removed snapshot `%s`.", backupSources),
+			)
 			return nil
 		})
 		if err := copy.Copy(s.c.BackupSources, backupSources, copy.Options{
 			PreserveTimes: true,
 			PreserveOwner: true,
 		}); err != nil {
-			return fmt.Errorf("takeBackup: error creating snapshot: %w", err)
+			return fmt.Errorf("createArchive: error creating snapshot: %w", err)
 		}
-		s.logger.Infof("Created snapshot of `%s` at `%s`.", s.c.BackupSources, backupSources)
+		s.logger.Info(
+			fmt.Sprintf("Created snapshot of `%s` at `%s`.", s.c.BackupSources, backupSources),
+		)
 	}
 
 	tarFile := s.file
 	s.registerHook(hookLevelPlumbing, func(error) error {
 		if err := remove(tarFile); err != nil {
-			return fmt.Errorf("takeBackup: error removing tar file: %w", err)
+			return fmt.Errorf("createArchive: error removing tar file: %w", err)
 		}
-		s.logger.Infof("Removed tar file `%s`.", tarFile)
+		s.logger.Info(
+			fmt.Sprintf("Removed tar file `%s`.", tarFile),
+		)
 		return nil
 	})
 
 	backupPath, err := filepath.Abs(stripTrailingSlashes(backupSources))
 	if err != nil {
-		return fmt.Errorf("takeBackup: error getting absolute path: %w", err)
+		return fmt.Errorf("createArchive: error getting absolute path: %w", err)
 	}
 
 	var filesEligibleForBackup []string
@@ -416,21 +486,23 @@ func (s *script) takeBackup() error {
 		filesEligibleForBackup = append(filesEligibleForBackup, path)
 		return nil
 	}); err != nil {
-		return fmt.Errorf("compress: error walking filesystem tree: %w", err)
+		return fmt.Errorf("createArchive: error walking filesystem tree: %w", err)
 	}
 
-	if err := createArchive(filesEligibleForBackup, backupSources, tarFile); err != nil {
+	if err := createArchive(filesEligibleForBackup, backupSources, tarFile, s.c.BackupCompression.String()); err != nil {
-		return fmt.Errorf("takeBackup: error compressing backup folder: %w", err)
+		return fmt.Errorf("createArchive: error compressing backup folder: %w", err)
 	}
 
-	s.logger.Infof("Created backup of `%s` at `%s`.", backupSources, tarFile)
+	s.logger.Info(
+		fmt.Sprintf("Created backup of `%s` at `%s`.", backupSources, tarFile),
+	)
 	return nil
 }
 
-// encryptBackup encrypts the backup file using PGP and the configured passphrase.
+// encryptArchive encrypts the backup file using PGP and the configured passphrase.
 // In case no passphrase is given it returns early, leaving the backup file
 // untouched.
-func (s *script) encryptBackup() error {
+func (s *script) encryptArchive() error {
 	if s.c.GpgPassphrase == "" {
 		return nil
 	}
@@ -438,48 +510,52 @@ func (s *script) encryptBackup() error {
 	gpgFile := fmt.Sprintf("%s.gpg", s.file)
 	s.registerHook(hookLevelPlumbing, func(error) error {
 		if err := remove(gpgFile); err != nil {
-			return fmt.Errorf("encryptBackup: error removing gpg file: %w", err)
+			return fmt.Errorf("encryptArchive: error removing gpg file: %w", err)
 		}
-		s.logger.Infof("Removed GPG file `%s`.", gpgFile)
+		s.logger.Info(
+			fmt.Sprintf("Removed GPG file `%s`.", gpgFile),
+		)
 		return nil
 	})
 
 	outFile, err := os.Create(gpgFile)
-	defer outFile.Close()
 	if err != nil {
-		return fmt.Errorf("encryptBackup: error opening out file: %w", err)
+		return fmt.Errorf("encryptArchive: error opening out file: %w", err)
 	}
+	defer outFile.Close()
 
 	_, name := path.Split(s.file)
 	dst, err := openpgp.SymmetricallyEncrypt(outFile, []byte(s.c.GpgPassphrase), &openpgp.FileHints{
 		IsBinary: true,
 		FileName: name,
 	}, nil)
-	defer dst.Close()
 	if err != nil {
-		return fmt.Errorf("encryptBackup: error encrypting backup file: %w", err)
+		return fmt.Errorf("encryptArchive: error encrypting backup file: %w", err)
 	}
+	defer dst.Close()
 
 	src, err := os.Open(s.file)
 	if err != nil {
-		return fmt.Errorf("encryptBackup: error opening backup file `%s`: %w", s.file, err)
+		return fmt.Errorf("encryptArchive: error opening backup file `%s`: %w", s.file, err)
 	}
 
 	if _, err := io.Copy(dst, src); err != nil {
-		return fmt.Errorf("encryptBackup: error writing ciphertext to file: %w", err)
+		return fmt.Errorf("encryptArchive: error writing ciphertext to file: %w", err)
 	}
 
 	s.file = gpgFile
-	s.logger.Infof("Encrypted backup using given passphrase, saving as `%s`.", s.file)
+	s.logger.Info(
+		fmt.Sprintf("Encrypted backup using given passphrase, saving as `%s`.", s.file),
+	)
 	return nil
 }
 
-// copyBackup makes sure the backup file is copied to both local and remote locations
+// copyArchive makes sure the backup file is copied to both local and remote locations
 // as per the given configuration.
-func (s *script) copyBackup() error {
+func (s *script) copyArchive() error {
 	_, name := path.Split(s.file)
 	if stat, err := os.Stat(s.file); err != nil {
-		return fmt.Errorf("copyBackup: unable to stat backup file: %w", err)
+		return fmt.Errorf("copyArchive: unable to stat backup file: %w", err)
 	} else {
 		size := stat.Size()
 		s.stats.BackupFile = BackupFileStats{
@@ -489,45 +565,17 @@ func (s *script) copyBackup() error {
 		}
 	}
 
-	if s.minioClient != nil {
+	eg := errgroup.Group{}
-		if _, err := s.minioClient.FPutObject(context.Background(), s.c.AwsS3BucketName, filepath.Join(s.c.AwsS3Path, name), s.file, minio.PutObjectOptions{
+	for _, backend := range s.storages {
-			ContentType: "application/tar+gzip",
+		b := backend
-		}); err != nil {
+		eg.Go(func() error {
-			return fmt.Errorf("copyBackup: error uploading backup to remote storage: %w", err)
+			return b.Copy(s.file)
-		}
+		})
-		s.logger.Infof("Uploaded a copy of backup `%s` to bucket `%s`.", s.file, s.c.AwsS3BucketName)
+	}
+	if err := eg.Wait(); err != nil {
+		return fmt.Errorf("copyArchive: error copying archive: %w", err)
 	}
 
-	if s.webdavClient != nil {
-		bytes, err := os.ReadFile(s.file)
-		if err != nil {
-			return fmt.Errorf("copyBackup: error reading the file to be uploaded: %w", err)
-		}
-		if err := s.webdavClient.MkdirAll(s.c.WebdavPath, 0644); err != nil {
-			return fmt.Errorf("copyBackup: error creating directory '%s' on WebDAV server: %w", s.c.WebdavPath, err)
-		}
-		if err := s.webdavClient.Write(filepath.Join(s.c.WebdavPath, name), bytes, 0644); err != nil {
-			return fmt.Errorf("copyBackup: error uploading the file to WebDAV server: %w", err)
-		}
-		s.logger.Infof("Uploaded a copy of backup `%s` to WebDAV-URL '%s' at path '%s'.", s.file, s.c.WebdavUrl, s.c.WebdavPath)
-	}
-
-	if _, err := os.Stat(s.c.BackupArchive); !os.IsNotExist(err) {
-		if err := copyFile(s.file, path.Join(s.c.BackupArchive, name)); err != nil {
-			return fmt.Errorf("copyBackup: error copying file to local archive: %w", err)
-		}
-		s.logger.Infof("Stored copy of backup `%s` in local archive `%s`.", s.file, s.c.BackupArchive)
-		if s.c.BackupLatestSymlink != "" {
-			symlink := path.Join(s.c.BackupArchive, s.c.BackupLatestSymlink)
-			if _, err := os.Lstat(symlink); err == nil {
-				os.Remove(symlink)
-			}
-			if err := os.Symlink(name, symlink); err != nil {
-				return fmt.Errorf("copyBackup: error creating latest symlink: %w", err)
-			}
-			s.logger.Infof("Created/Updated symlink `%s` for latest backup.", s.c.BackupLatestSymlink)
-		}
-	}
 	return nil
 }
 
@@ -541,177 +589,34 @@ func (s *script) pruneBackups() error {
 
 	deadline := time.Now().AddDate(0, 0, -int(s.c.BackupRetentionDays)).Add(s.c.BackupPruningLeeway)
 
-	// doPrune holds general control flow that applies to any kind of storage.
+	eg := errgroup.Group{}
-	// Callers can pass in a thunk that performs the actual deletion of files.
+	for _, backend := range s.storages {
-	var doPrune = func(lenMatches, lenCandidates int, description string, doRemoveFiles func() error) error {
+		b := backend
-		if lenMatches != 0 && lenMatches != lenCandidates {
+		eg.Go(func() error {
-			if err := doRemoveFiles(); err != nil {
+			if skipPrune(b.Name(), s.c.BackupSkipBackendsFromPrune) {
+				s.logger.Info(
+					fmt.Sprintf("Skipping pruning for backend `%s`.", b.Name()),
+				)
+				return nil
+			}
+			stats, err := b.Prune(deadline, s.c.BackupPruningPrefix)
+			if err != nil {
 				return err
 			}
-			s.logger.Infof(
+			s.stats.Lock()
-				"Pruned %d out of %d %s as their age exceeded the configured retention period of %d days.",
+			s.stats.Storages[b.Name()] = StorageStats{
-				lenMatches,
+				Total:  stats.Total,
-				lenCandidates,
+				Pruned: stats.Pruned,
-				description,
-				s.c.BackupRetentionDays,
-			)
-		} else if lenMatches != 0 && lenMatches == lenCandidates {
-			s.logger.Warnf("The current configuration would delete all %d existing %s.", lenMatches, description)
-			s.logger.Warn("Refusing to do so, please check your configuration.")
-		} else {
-			s.logger.Infof("None of %d existing %s were pruned.", lenCandidates, description)
-		}
-		return nil
-	}
-
-	if s.minioClient != nil {
-		candidates := s.minioClient.ListObjects(context.Background(), s.c.AwsS3BucketName, minio.ListObjectsOptions{
-			WithMetadata: true,
-			Prefix:       filepath.Join(s.c.AwsS3Path, s.c.BackupPruningPrefix),
-			Recursive:    true,
-		})
-
-		var matches []minio.ObjectInfo
-		var lenCandidates int
-		for candidate := range candidates {
-			lenCandidates++
-			if candidate.Err != nil {
-				return fmt.Errorf(
-					"pruneBackups: error looking up candidates from remote storage: %w",
-					candidate.Err,
-				)
-			}
-			if candidate.LastModified.Before(deadline) {
-				matches = append(matches, candidate)
-			}
-		}
-
-		s.stats.Storages.S3 = StorageStats{
-			Total:  uint(lenCandidates),
-			Pruned: uint(len(matches)),
-		}
-
-		doPrune(len(matches), lenCandidates, "remote backup(s)", func() error {
-			objectsCh := make(chan minio.ObjectInfo)
-			go func() {
-				for _, match := range matches {
-					objectsCh <- match
-				}
-				close(objectsCh)
-			}()
-			errChan := s.minioClient.RemoveObjects(context.Background(), s.c.AwsS3BucketName, objectsCh, minio.RemoveObjectsOptions{})
-			var removeErrors []error
-			for result := range errChan {
-				if result.Err != nil {
-					removeErrors = append(removeErrors, result.Err)
-				}
-			}
-			if len(removeErrors) != 0 {
-				return join(removeErrors...)
 			}
+			s.stats.Unlock()
 			return nil
 		})
 	}
 
-	if s.webdavClient != nil {
+	if err := eg.Wait(); err != nil {
-		candidates, err := s.webdavClient.ReadDir(s.c.WebdavPath)
+		return fmt.Errorf("pruneBackups: error pruning backups: %w", err)
-		if err != nil {
-			return fmt.Errorf("pruneBackups: error looking up candidates from remote storage: %w", err)
-		}
-		var matches []fs.FileInfo
-		var lenCandidates int
-		for _, candidate := range candidates {
-			if !strings.HasPrefix(candidate.Name(), s.c.BackupPruningPrefix) {
-				continue
-			}
-			lenCandidates++
-			if candidate.ModTime().Before(deadline) {
-				matches = append(matches, candidate)
-			}
-		}
-
-		s.stats.Storages.WebDAV = StorageStats{
-			Total:  uint(lenCandidates),
-			Pruned: uint(len(matches)),
-		}
-
-		doPrune(len(matches), lenCandidates, "WebDAV backup(s)", func() error {
-			for _, match := range matches {
-				if err := s.webdavClient.Remove(filepath.Join(s.c.WebdavPath, match.Name())); err != nil {
-					return fmt.Errorf("pruneBackups: error removing file from WebDAV storage: %w", err)
-				}
-			}
-			return nil
-		})
 	}
 
-	if _, err := os.Stat(s.c.BackupArchive); !os.IsNotExist(err) {
-		globPattern := path.Join(
-			s.c.BackupArchive,
-			fmt.Sprintf("%s*", s.c.BackupPruningPrefix),
-		)
-		globMatches, err := filepath.Glob(globPattern)
-		if err != nil {
-			return fmt.Errorf(
-				"pruneBackups: error looking up matching files using pattern %s: %w",
-				globPattern,
-				err,
-			)
-		}
-
-		var candidates []string
-		for _, candidate := range globMatches {
-			fi, err := os.Lstat(candidate)
-			if err != nil {
-				return fmt.Errorf(
-					"pruneBackups: error calling Lstat on file %s: %w",
-					candidate,
-					err,
-				)
-			}
-
-			if fi.Mode()&os.ModeSymlink != os.ModeSymlink {
-				candidates = append(candidates, candidate)
-			}
-		}
-
-		var matches []string
-		for _, candidate := range candidates {
-			fi, err := os.Stat(candidate)
-			if err != nil {
-				return fmt.Errorf(
-					"pruneBackups: error calling stat on file %s: %w",
-					candidate,
-					err,
-				)
-			}
-			if fi.ModTime().Before(deadline) {
-				matches = append(matches, candidate)
-			}
-		}
-
-		s.stats.Storages.Local = StorageStats{
-			Total:  uint(len(candidates)),
-			Pruned: uint(len(matches)),
-		}
-
-		doPrune(len(matches), len(candidates), "local backup(s)", func() error {
-			var removeErrors []error
-			for _, match := range matches {
-				if err := os.Remove(match); err != nil {
-					removeErrors = append(removeErrors, err)
-				}
-			}
-			if len(removeErrors) != 0 {
-				return fmt.Errorf(
-					"pruneBackups: %d error(s) deleting local files, starting with: %w",
-					len(removeErrors),
-					join(removeErrors...),
-				)
-			}
-			return nil
-		})
-	}
 	return nil
 }
 
@@ -719,7 +624,20 @@ func (s *script) pruneBackups() error {
 // is non-nil.
 func (s *script) must(err error) {
 	if err != nil {
-		s.logger.Errorf("Fatal error running backup: %s", err)
+		s.logger.Error(
+			fmt.Sprintf("Fatal error running backup: %s", err),
+		)
 		panic(err)
 	}
 }
+
+// skipPrune returns true if the given backend name is contained in the
+// list of skipped backends.
+func skipPrune(name string, skippedBackends []string) bool {
+	return slices.ContainsFunc(
+		skippedBackends,
+		func(b string) bool {
+			return strings.EqualFold(b, name) // ignore case on both sides
+		},
+	)
+}

cmd/backup/stats.go

@@ -5,6 +5,7 @@ package main
 
 import (
 	"bytes"
+	"sync"
 	"time"
 )
 
@@ -30,15 +31,9 @@ type StorageStats struct {
 	PruneErrors uint
 }
 
-// StoragesStats stats about each possible archival location (Local, WebDAV, S3)
-type StoragesStats struct {
-	Local  StorageStats
-	WebDAV StorageStats
-	S3     StorageStats
-}
-
 // Stats global stats regarding script execution
 type Stats struct {
+	sync.Mutex
 	StartTime  time.Time
 	EndTime    time.Time
 	TookTime   time.Duration
@@ -46,5 +41,5 @@ type Stats struct {
 	LogOutput  *bytes.Buffer
 	Containers ContainersStats
 	BackupFile BackupFileStats
-	Storages   StoragesStats
+	Storages   map[string]StorageStats
 }

cmd/backup/util.go

@@ -5,51 +5,13 @@ package main
 
 import (
 	"bytes"
-	"errors"
 	"fmt"
 	"io"
 	"os"
-	"strings"
 )
 
 var noop = func() error { return nil }
 
-// copy creates a copy of the file located at `dst` at `src`.
-func copyFile(src, dst string) error {
-	in, err := os.Open(src)
-	if err != nil {
-		return err
-	}
-	defer in.Close()
-
-	out, err := os.Create(dst)
-	if err != nil {
-		return err
-	}
-
-	_, err = io.Copy(out, in)
-	if err != nil {
-		out.Close()
-		return err
-	}
-	return out.Close()
-}
-
-// join takes a list of errors and joins them into a single error
-func join(errs ...error) error {
-	if len(errs) == 1 {
-		return errs[0]
-	}
-	var msgs []string
-	for _, err := range errs {
-		if err == nil {
-			continue
-		}
-		msgs = append(msgs, err.Error())
-	}
-	return errors.New("[" + strings.Join(msgs, ", ") + "]")
-}
-
 // remove removes the given file or directory from disk.
 func remove(location string) error {
 	fi, err := os.Lstat(location)
@@ -84,7 +46,7 @@ type bufferingWriter struct {
 
 func (b *bufferingWriter) Write(p []byte) (n int, err error) {
 	if n, err := b.buf.Write(p); err != nil {
-		return n, fmt.Errorf("bufferingWriter: error writing to buffer: %w", err)
+		return n, fmt.Errorf("(*bufferingWriter).Write: error writing to buffer: %w", err)
 	}
 	return b.writer.Write(p)
 }

docs/NOTIFICATION-TEMPLATES.md

@@ -25,15 +25,16 @@ Here is a list of all data passed to the template:
     * `FullPath`: full path of the backup file (e.g. `/archive/backup-2022-02-11T01-00-00.tar.gz`)
     * `Size`: size in bytes of the backup file
   * `Storages`: object that holds stats about each storage
-    * `Local`, `S3` or `WebDAV`:
+    * `Local`, `S3`, `WebDAV`, `Azure` or `SSH`:
       * `Total`: total number of backup files
       * `Pruned`: number of backup files that were deleted due to pruning rule
       * `PruneErrors`: number of backup files that were unable to be pruned
 
 ## Functions
 
-Some formatting functions are also available:
+Some formatting and helper functions are also available:
 
 * `formatTime`: formats a time object using [RFC3339](https://datatracker.ietf.org/doc/html/rfc3339) format (e.g. `2022-02-11T01:00:00Z`)
 * `formatBytesBin`: formats an amount of bytes using powers of 1024 (e.g. `7055258` bytes will be `6.7 MiB`) 
 * `formatBytesDec`: formats an amount of bytes using powers of 1000 (e.g. `7055258` bytes will be `7.1 MB`)
+* `env`: returns the value of the environment variable of the given key if set

entrypoint.sh

@@ -13,6 +13,7 @@ if [ ! -d "/etc/dockervolumebackup/conf.d" ]; then
 else
   echo "/etc/dockervolumebackup/conf.d was found, using configuration files from this directory."
 
+  crontab -r && crontab /dev/null
   for file in /etc/dockervolumebackup/conf.d/*; do
     source $file
     BACKUP_CRON_EXPRESSION="${BACKUP_CRON_EXPRESSION:-@daily}"
@@ -22,4 +23,4 @@ else
 fi
 
 echo "Starting cron in foreground."
-crond -f -l 8
+crond -f -d 8

go.mod

@@ -1,65 +1,71 @@
 module github.com/offen/docker-volume-backup
 
-go 1.18
+go 1.21
 
 require (
-	github.com/containrrr/shoutrrr v0.5.2
+	github.com/Azure/azure-sdk-for-go/sdk/azidentity v1.3.0
+	github.com/Azure/azure-sdk-for-go/sdk/storage/azblob v1.1.0
+	github.com/containrrr/shoutrrr v0.7.1
 	github.com/cosiner/argv v0.1.0
-	github.com/docker/docker v20.10.11+incompatible
+	github.com/docker/docker v24.0.5+incompatible
 	github.com/gofrs/flock v0.8.1
 	github.com/kelseyhightower/envconfig v1.4.0
+	github.com/klauspost/compress v1.16.7
 	github.com/leekchan/timeutil v0.0.0-20150802142658-28917288c48d
-	github.com/minio/minio-go/v7 v7.0.16
+	github.com/minio/minio-go/v7 v7.0.62
-	github.com/otiai10/copy v1.7.0
+	github.com/otiai10/copy v1.11.0
-	github.com/sirupsen/logrus v1.8.1
+	github.com/pkg/sftp v1.13.6
-	github.com/studio-b12/gowebdav v0.0.0-20220128162035-c7b1ff8a5e62
+	github.com/studio-b12/gowebdav v0.9.0
-	golang.org/x/crypto v0.0.0-20210817164053-32db794688a5
+	golang.org/x/crypto v0.12.0
-	golang.org/x/sync v0.0.0-20220601150217-0de741cfad7f
+	golang.org/x/oauth2 v0.0.0-20221014153046-6fdb5e3db783
+	golang.org/x/sync v0.3.0
 )
 
 require (
+	github.com/cloudflare/circl v1.3.3 // indirect
+	github.com/golang/protobuf v1.5.2 // indirect
+	google.golang.org/appengine v1.6.7 // indirect
+	google.golang.org/protobuf v1.28.1 // indirect
+)
+
+require (
+	github.com/Azure/azure-sdk-for-go/sdk/azcore v1.6.0 // indirect
+	github.com/Azure/azure-sdk-for-go/sdk/internal v1.3.0 // indirect
+	github.com/AzureAD/microsoft-authentication-library-for-go v1.0.0 // indirect
 	github.com/Microsoft/go-winio v0.5.2 // indirect
-	github.com/containerd/containerd v1.6.6 // indirect
+	github.com/ProtonMail/go-crypto v0.0.0-20230717121422-5aa5874ade95
-	github.com/docker/distribution v2.7.1+incompatible // indirect
+	github.com/docker/distribution v2.8.2+incompatible // indirect
 	github.com/docker/go-connections v0.4.0 // indirect
 	github.com/docker/go-units v0.4.0 // indirect
-	github.com/dustin/go-humanize v1.0.0 // indirect
+	github.com/dropbox/dropbox-sdk-go-unofficial/v6 v6.0.5
-	github.com/fatih/color v1.10.0 // indirect
+	github.com/dustin/go-humanize v1.0.1 // indirect
-	github.com/fsnotify/fsnotify v1.4.9 // indirect
+	github.com/fatih/color v1.13.0 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
-	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/golang-jwt/jwt/v4 v4.5.0 // indirect
 	github.com/google/uuid v1.3.0 // indirect
-	github.com/gorilla/mux v1.7.3 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
-	github.com/klauspost/compress v1.15.6 // indirect
+	github.com/klauspost/cpuid/v2 v2.2.5 // indirect
-	github.com/klauspost/cpuid/v2 v2.0.9 // indirect
+	github.com/kr/fs v0.1.0 // indirect
-	github.com/kr/text v0.2.0 // indirect
+	github.com/kylelemons/godebug v1.1.0 // indirect
-	github.com/mattn/go-colorable v0.1.8 // indirect
+	github.com/mattn/go-colorable v0.1.13 // indirect
-	github.com/mattn/go-isatty v0.0.12 // indirect
+	github.com/mattn/go-isatty v0.0.16 // indirect
 	github.com/minio/md5-simd v1.1.2 // indirect
-	github.com/minio/sha256-simd v1.0.0 // indirect
+	github.com/minio/sha256-simd v1.0.1 // indirect
-	github.com/mitchellh/go-homedir v1.1.0 // indirect
 	github.com/moby/term v0.0.0-20200312100748-672ec06f55cd // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
 	github.com/morikuni/aec v1.0.0 // indirect
 	github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e // indirect
-	github.com/nxadm/tail v1.4.6 // indirect
-	github.com/onsi/ginkgo v1.14.2 // indirect
-	github.com/onsi/gomega v1.10.3 // indirect
 	github.com/opencontainers/go-digest v1.0.0 // indirect
 	github.com/opencontainers/image-spec v1.0.3-0.20211202183452-c5a74bcca799 // indirect
+	github.com/pkg/browser v0.0.0-20210911075715-681adbf594b8 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
-	github.com/rs/xid v1.3.0 // indirect
+	github.com/rs/xid v1.5.0 // indirect
-	golang.org/x/net v0.0.0-20220607020251-c690dde0001d // indirect
+	github.com/sirupsen/logrus v1.9.3 // indirect
-	golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a // indirect
+	golang.org/x/net v0.14.0 // indirect
-	golang.org/x/text v0.3.7 // indirect
+	golang.org/x/sys v0.11.0 // indirect
-	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
+	golang.org/x/text v0.12.0 // indirect
-	google.golang.org/genproto v0.0.0-20220602131408-e326c6e8e9c8 // indirect
-	google.golang.org/grpc v1.47.0 // indirect
-	google.golang.org/protobuf v1.28.0 // indirect
 	gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f // indirect
-	gopkg.in/ini.v1 v1.65.0 // indirect
+	gopkg.in/ini.v1 v1.67.0 // indirect
-	gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7 // indirect
+	gotest.tools/v3 v3.0.3 // indirect
-	gopkg.in/yaml.v2 v2.4.0 // indirect
 )

internal/storage/azure/azure.go

@@ -0,0 +1,160 @@
+// Copyright 2022 - Offen Authors <hioffen@posteo.de>
+// SPDX-License-Identifier: MPL-2.0
+
+package azure
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"text/template"
+	"time"
+
+	"github.com/Azure/azure-sdk-for-go/sdk/azidentity"
+	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob"
+	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/container"
+	"github.com/offen/docker-volume-backup/internal/storage"
+)
+
+type azureBlobStorage struct {
+	*storage.StorageBackend
+	client        *azblob.Client
+	containerName string
+}
+
+// Config contains values that define the configuration of an Azure Blob Storage.
+type Config struct {
+	AccountName       string
+	ContainerName     string
+	PrimaryAccountKey string
+	Endpoint          string
+	RemotePath        string
+}
+
+// NewStorageBackend creates and initializes a new Azure Blob Storage backend.
+func NewStorageBackend(opts Config, logFunc storage.Log) (storage.Backend, error) {
+	endpointTemplate, err := template.New("endpoint").Parse(opts.Endpoint)
+	if err != nil {
+		return nil, fmt.Errorf("NewStorageBackend: error parsing endpoint template: %w", err)
+	}
+	var ep bytes.Buffer
+	if err := endpointTemplate.Execute(&ep, opts); err != nil {
+		return nil, fmt.Errorf("NewStorageBackend: error executing endpoint template: %w", err)
+	}
+	normalizedEndpoint := fmt.Sprintf("%s/", strings.TrimSuffix(ep.String(), "/"))
+
+	var client *azblob.Client
+	if opts.PrimaryAccountKey != "" {
+		cred, err := azblob.NewSharedKeyCredential(opts.AccountName, opts.PrimaryAccountKey)
+		if err != nil {
+			return nil, fmt.Errorf("NewStorageBackend: error creating shared key Azure credential: %w", err)
+		}
+
+		client, err = azblob.NewClientWithSharedKeyCredential(normalizedEndpoint, cred, nil)
+		if err != nil {
+			return nil, fmt.Errorf("NewStorageBackend: error creating Azure client: %w", err)
+		}
+	} else {
+		cred, err := azidentity.NewManagedIdentityCredential(nil)
+		if err != nil {
+			return nil, fmt.Errorf("NewStorageBackend: error creating managed identity credential: %w", err)
+		}
+		client, err = azblob.NewClient(normalizedEndpoint, cred, nil)
+		if err != nil {
+			return nil, fmt.Errorf("NewStorageBackend: error creating Azure client: %w", err)
+		}
+	}
+
+	storage := azureBlobStorage{
+		client:        client,
+		containerName: opts.ContainerName,
+		StorageBackend: &storage.StorageBackend{
+			DestinationPath: opts.RemotePath,
+			Log:             logFunc,
+		},
+	}
+	return &storage, nil
+}
+
+// Name returns the name of the storage backend
+func (b *azureBlobStorage) Name() string {
+	return "Azure"
+}
+
+// Copy copies the given file to the storage backend.
+func (b *azureBlobStorage) Copy(file string) error {
+	fileReader, err := os.Open(file)
+	if err != nil {
+		return fmt.Errorf("(*azureBlobStorage).Copy: error opening file %s: %w", file, err)
+	}
+	_, err = b.client.UploadStream(
+		context.Background(),
+		b.containerName,
+		filepath.Join(b.DestinationPath, filepath.Base(file)),
+		fileReader,
+		nil,
+	)
+	if err != nil {
+		return fmt.Errorf("(*azureBlobStorage).Copy: error uploading file %s: %w", file, err)
+	}
+	return nil
+}
+
+// Prune rotates away backups according to the configuration and provided
+// deadline for the Azure Blob storage backend.
+func (b *azureBlobStorage) Prune(deadline time.Time, pruningPrefix string) (*storage.PruneStats, error) {
+	lookupPrefix := filepath.Join(b.DestinationPath, pruningPrefix)
+	pager := b.client.NewListBlobsFlatPager(b.containerName, &container.ListBlobsFlatOptions{
+		Prefix: &lookupPrefix,
+	})
+	var matches []string
+	var totalCount uint
+	for pager.More() {
+		resp, err := pager.NextPage(context.Background())
+		if err != nil {
+			return nil, fmt.Errorf("(*azureBlobStorage).Prune: error paging over blobs: %w", err)
+		}
+		for _, v := range resp.Segment.BlobItems {
+			totalCount++
+			if v.Properties.LastModified.Before(deadline) {
+				matches = append(matches, *v.Name)
+			}
+		}
+	}
+
+	stats := storage.PruneStats{
+		Total:  totalCount,
+		Pruned: uint(len(matches)),
+	}
+
+	if err := b.DoPrune(b.Name(), len(matches), int(totalCount), func() error {
+		wg := sync.WaitGroup{}
+		wg.Add(len(matches))
+		var errs []error
+
+		for _, match := range matches {
+			name := match
+			go func() {
+				_, err := b.client.DeleteBlob(context.Background(), b.containerName, name, nil)
+				if err != nil {
+					errs = append(errs, err)
+				}
+				wg.Done()
+			}()
+		}
+		wg.Wait()
+		if len(errs) != 0 {
+			return errors.Join(errs...)
+		}
+		return nil
+	}); err != nil {
+		return &stats, err
+	}
+
+	return &stats, nil
+}

internal/storage/dropbox/dropbox.go

@@ -0,0 +1,260 @@
+package dropbox
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"net/url"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/dropbox/dropbox-sdk-go-unofficial/v6/dropbox"
+	"github.com/dropbox/dropbox-sdk-go-unofficial/v6/dropbox/files"
+	"github.com/offen/docker-volume-backup/internal/storage"
+	"golang.org/x/oauth2"
+)
+
+type dropboxStorage struct {
+	*storage.StorageBackend
+	client           files.Client
+	concurrencyLevel int
+}
+
+// Config allows to configure a Dropbox storage backend.
+type Config struct {
+	Endpoint         string
+	OAuth2Endpoint   string
+	RefreshToken     string
+	AppKey           string
+	AppSecret        string
+	RemotePath       string
+	ConcurrencyLevel int
+}
+
+// NewStorageBackend creates and initializes a new Dropbox storage backend.
+func NewStorageBackend(opts Config, logFunc storage.Log) (storage.Backend, error) {
+	tokenUrl, _ := url.JoinPath(opts.OAuth2Endpoint, "oauth2/token")
+
+	conf := &oauth2.Config{
+		ClientID:     opts.AppKey,
+		ClientSecret: opts.AppSecret,
+		Endpoint: oauth2.Endpoint{
+			TokenURL: tokenUrl,
+		},
+	}
+
+	logFunc(storage.LogLevelInfo, "Dropbox", "Fetching fresh access token for Dropbox storage backend.")
+	tkSource := conf.TokenSource(context.Background(), &oauth2.Token{RefreshToken: opts.RefreshToken})
+	token, err := tkSource.Token()
+	if err != nil {
+		return nil, fmt.Errorf("(*dropboxStorage).NewStorageBackend: Error refreshing token: %w", err)
+	}
+
+	dbxConfig := dropbox.Config{
+		Token: token.AccessToken,
+	}
+
+	if opts.Endpoint != "https://api.dropbox.com/" {
+		dbxConfig.URLGenerator = func(hostType string, namespace string, route string) string {
+			return fmt.Sprintf("%s/%d/%s/%s", opts.Endpoint, 2, namespace, route)
+		}
+	}
+
+	client := files.New(dbxConfig)
+
+	if opts.ConcurrencyLevel < 1 {
+		logFunc(storage.LogLevelWarning, "Dropbox", "Concurrency level must be at least 1! Using 1 instead of %d.", opts.ConcurrencyLevel)
+		opts.ConcurrencyLevel = 1
+	}
+
+	return &dropboxStorage{
+		StorageBackend: &storage.StorageBackend{
+			DestinationPath: opts.RemotePath,
+			Log:             logFunc,
+		},
+		client:           client,
+		concurrencyLevel: opts.ConcurrencyLevel,
+	}, nil
+}
+
+// Name returns the name of the storage backend
+func (b *dropboxStorage) Name() string {
+	return "Dropbox"
+}
+
+// Copy copies the given file to the WebDav storage backend.
+func (b *dropboxStorage) Copy(file string) error {
+	_, name := path.Split(file)
+
+	folderArg := files.NewCreateFolderArg(b.DestinationPath)
+	if _, err := b.client.CreateFolderV2(folderArg); err != nil {
+		switch err := err.(type) {
+		case files.CreateFolderV2APIError:
+			if err.EndpointError.Path.Tag != files.WriteErrorConflict {
+				return fmt.Errorf("(*dropboxStorage).Copy: Error creating directory '%s': %w", b.DestinationPath, err)
+			}
+			b.Log(storage.LogLevelInfo, b.Name(), "Destination path '%s' already exists, no new directory required.", b.DestinationPath)
+		default:
+			return fmt.Errorf("(*dropboxStorage).Copy: Error creating directory '%s': %w", b.DestinationPath, err)
+		}
+	}
+
+	r, err := os.Open(file)
+	if err != nil {
+		return fmt.Errorf("(*dropboxStorage).Copy: Error opening the file to be uploaded: %w", err)
+	}
+	defer r.Close()
+
+	// Start new upload session and get session id
+
+	b.Log(storage.LogLevelInfo, b.Name(), "Starting upload session for backup '%s' at path '%s'.", file, b.DestinationPath)
+
+	var sessionId string
+	uploadSessionStartArg := files.NewUploadSessionStartArg()
+	uploadSessionStartArg.SessionType = &files.UploadSessionType{Tagged: dropbox.Tagged{Tag: files.UploadSessionTypeConcurrent}}
+	if res, err := b.client.UploadSessionStart(uploadSessionStartArg, nil); err != nil {
+		return fmt.Errorf("(*dropboxStorage).Copy: Error starting the upload session: %w", err)
+	} else {
+		sessionId = res.SessionId
+	}
+
+	// Send the file in 148MB chunks (Dropbox API limit is 150MB, concurrent upload requires a multiple of 4MB though)
+	// Last append can be any size <= 150MB with Close=True
+
+	const chunkSize = 148 * 1024 * 1024 // 148MB
+	var offset uint64 = 0
+	var guard = make(chan struct{}, b.concurrencyLevel)
+	var errorChn = make(chan error, b.concurrencyLevel)
+	var EOFChn = make(chan bool, b.concurrencyLevel)
+	var mu sync.Mutex
+	var wg sync.WaitGroup
+
+loop:
+	for {
+		guard <- struct{}{} // limit concurrency
+		select {
+		case err := <-errorChn: // error from goroutine
+			return err
+		case <-EOFChn: // EOF from goroutine
+			wg.Wait() // wait for all goroutines to finish
+			break loop
+		default:
+		}
+
+		go func() {
+			defer func() {
+				wg.Done()
+				<-guard
+			}()
+			wg.Add(1)
+			chunk := make([]byte, chunkSize)
+
+			mu.Lock() // to preserve offset of chunks
+
+			select {
+			case <-EOFChn:
+				EOFChn <- true // put it back for outer loop
+				mu.Unlock()
+				return // already EOF
+			default:
+			}
+
+			bytesRead, err := r.Read(chunk)
+			if err != nil {
+				errorChn <- fmt.Errorf("(*dropboxStorage).Copy: Error reading the file to be uploaded: %w", err)
+				mu.Unlock()
+				return
+			}
+			chunk = chunk[:bytesRead]
+
+			uploadSessionAppendArg := files.NewUploadSessionAppendArg(
+				files.NewUploadSessionCursor(sessionId, offset),
+			)
+			isEOF := bytesRead < chunkSize
+			uploadSessionAppendArg.Close = isEOF
+			if isEOF {
+				EOFChn <- true
+			}
+			offset += uint64(bytesRead)
+
+			mu.Unlock()
+
+			if err := b.client.UploadSessionAppendV2(uploadSessionAppendArg, bytes.NewReader(chunk)); err != nil {
+				errorChn <- fmt.Errorf("(*dropboxStorage).Copy: Error appending the file to the upload session: %w", err)
+				return
+			}
+		}()
+	}
+
+	// Finish the upload session, commit the file (no new data added)
+
+	_, err = b.client.UploadSessionFinish(
+		files.NewUploadSessionFinishArg(
+			files.NewUploadSessionCursor(sessionId, 0),
+			files.NewCommitInfo(filepath.Join(b.DestinationPath, name)),
+		), nil)
+	if err != nil {
+		return fmt.Errorf("(*dropboxStorage).Copy: Error finishing the upload session: %w", err)
+	}
+
+	b.Log(storage.LogLevelInfo, b.Name(), "Uploaded a copy of backup '%s' at path '%s'.", file, b.DestinationPath)
+
+	return nil
+}
+
+// Prune rotates away backups according to the configuration and provided deadline for the Dropbox storage backend.
+func (b *dropboxStorage) Prune(deadline time.Time, pruningPrefix string) (*storage.PruneStats, error) {
+	var entries []files.IsMetadata
+	res, err := b.client.ListFolder(files.NewListFolderArg(b.DestinationPath))
+	if err != nil {
+		return nil, fmt.Errorf("(*webDavStorage).Prune: Error looking up candidates from remote storage: %w", err)
+	}
+	entries = append(entries, res.Entries...)
+
+	for res.HasMore {
+		res, err = b.client.ListFolderContinue(files.NewListFolderContinueArg(res.Cursor))
+		if err != nil {
+			return nil, fmt.Errorf("(*webDavStorage).Prune: Error looking up candidates from remote storage: %w", err)
+		}
+		entries = append(entries, res.Entries...)
+	}
+
+	var matches []*files.FileMetadata
+	var lenCandidates int
+	for _, candidate := range entries {
+		switch candidate := candidate.(type) {
+		case *files.FileMetadata:
+			if !strings.HasPrefix(candidate.Name, pruningPrefix) {
+				continue
+			}
+			lenCandidates++
+			if candidate.ServerModified.Before(deadline) {
+				matches = append(matches, candidate)
+			}
+		default:
+			continue
+		}
+	}
+
+	stats := &storage.PruneStats{
+		Total:  uint(lenCandidates),
+		Pruned: uint(len(matches)),
+	}
+
+	if err := b.DoPrune(b.Name(), len(matches), lenCandidates, func() error {
+		for _, match := range matches {
+			if _, err := b.client.DeleteV2(files.NewDeleteArg(filepath.Join(b.DestinationPath, match.Name))); err != nil {
+				return fmt.Errorf("(*dropboxStorage).Prune: Error removing file from Dropbox storage: %w", err)
+			}
+		}
+		return nil
+	}); err != nil {
+		return stats, err
+	}
+
+	return stats, nil
+}

internal/storage/local/local.go

@@ -0,0 +1,160 @@
+// Copyright 2022 - Offen Authors <hioffen@posteo.de>
+// SPDX-License-Identifier: MPL-2.0
+
+package local
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"path"
+	"path/filepath"
+	"time"
+
+	"github.com/offen/docker-volume-backup/internal/storage"
+)
+
+type localStorage struct {
+	*storage.StorageBackend
+	latestSymlink string
+}
+
+// Config allows configuration of a local storage backend.
+type Config struct {
+	ArchivePath   string
+	LatestSymlink string
+}
+
+// NewStorageBackend creates and initializes a new local storage backend.
+func NewStorageBackend(opts Config, logFunc storage.Log) storage.Backend {
+	return &localStorage{
+		StorageBackend: &storage.StorageBackend{
+			DestinationPath: opts.ArchivePath,
+			Log:             logFunc,
+		},
+		latestSymlink: opts.LatestSymlink,
+	}
+}
+
+// Name return the name of the storage backend
+func (b *localStorage) Name() string {
+	return "Local"
+}
+
+// Copy copies the given file to the local storage backend.
+func (b *localStorage) Copy(file string) error {
+	_, name := path.Split(file)
+
+	if err := copyFile(file, path.Join(b.DestinationPath, name)); err != nil {
+		return fmt.Errorf("(*localStorage).Copy: Error copying file to archive: %w", err)
+	}
+	b.Log(storage.LogLevelInfo, b.Name(), "Stored copy of backup `%s` in `%s`.", file, b.DestinationPath)
+
+	if b.latestSymlink != "" {
+		symlink := path.Join(b.DestinationPath, b.latestSymlink)
+		if _, err := os.Lstat(symlink); err == nil {
+			os.Remove(symlink)
+		}
+		if err := os.Symlink(name, symlink); err != nil {
+			return fmt.Errorf("(*localStorage).Copy: error creating latest symlink: %w", err)
+		}
+		b.Log(storage.LogLevelInfo, b.Name(), "Created/Updated symlink `%s` for latest backup.", b.latestSymlink)
+	}
+
+	return nil
+}
+
+// Prune rotates away backups according to the configuration and provided deadline for the local storage backend.
+func (b *localStorage) Prune(deadline time.Time, pruningPrefix string) (*storage.PruneStats, error) {
+	globPattern := path.Join(
+		b.DestinationPath,
+		fmt.Sprintf("%s*", pruningPrefix),
+	)
+	globMatches, err := filepath.Glob(globPattern)
+	if err != nil {
+		return nil, fmt.Errorf(
+			"(*localStorage).Prune: Error looking up matching files using pattern %s: %w",
+			globPattern,
+			err,
+		)
+	}
+
+	var candidates []string
+	for _, candidate := range globMatches {
+		fi, err := os.Lstat(candidate)
+		if err != nil {
+			return nil, fmt.Errorf(
+				"(*localStorage).Prune: Error calling Lstat on file %s: %w",
+				candidate,
+				err,
+			)
+		}
+
+		if fi.Mode()&os.ModeSymlink != os.ModeSymlink {
+			candidates = append(candidates, candidate)
+		}
+	}
+
+	var matches []string
+	for _, candidate := range candidates {
+		fi, err := os.Stat(candidate)
+		if err != nil {
+			return nil, fmt.Errorf(
+				"(*localStorage).Prune: Error calling stat on file %s: %w",
+				candidate,
+				err,
+			)
+		}
+		if fi.ModTime().Before(deadline) {
+			matches = append(matches, candidate)
+		}
+	}
+
+	stats := &storage.PruneStats{
+		Total:  uint(len(candidates)),
+		Pruned: uint(len(matches)),
+	}
+
+	if err := b.DoPrune(b.Name(), len(matches), len(candidates), func() error {
+		var removeErrors []error
+		for _, match := range matches {
+			if err := os.Remove(match); err != nil {
+				removeErrors = append(removeErrors, err)
+			}
+		}
+		if len(removeErrors) != 0 {
+			return fmt.Errorf(
+				"(*localStorage).Prune: %d error(s) deleting files, starting with: %w",
+				len(removeErrors),
+				errors.Join(removeErrors...),
+			)
+		}
+		return nil
+	}); err != nil {
+		return stats, err
+	}
+
+	return stats, nil
+}
+
+// copy creates a copy of the file located at `dst` at `src`.
+func copyFile(src, dst string) error {
+	in, err := os.Open(src)
+	if err != nil {
+		return err
+	}
+	defer in.Close()
+
+	out, err := os.Create(dst)
+	if err != nil {
+		return err
+	}
+
+	_, err = io.Copy(out, in)
+	if err != nil {
+		out.Close()
+		return err
+	}
+	return out.Close()
+}

internal/storage/s3/s3.go

@@ -0,0 +1,194 @@
+// Copyright 2022 - Offen Authors <hioffen@posteo.de>
+// SPDX-License-Identifier: MPL-2.0
+
+package s3
+
+import (
+	"context"
+	"crypto/x509"
+	"errors"
+	"fmt"
+	"os"
+	"path"
+	"path/filepath"
+	"time"
+
+	"github.com/minio/minio-go/v7"
+	"github.com/minio/minio-go/v7/pkg/credentials"
+	"github.com/offen/docker-volume-backup/internal/storage"
+)
+
+type s3Storage struct {
+	*storage.StorageBackend
+	client       *minio.Client
+	bucket       string
+	storageClass string
+	partSize     int64
+}
+
+// Config contains values that define the configuration of a S3 backend.
+type Config struct {
+	Endpoint         string
+	AccessKeyID      string
+	SecretAccessKey  string
+	IamRoleEndpoint  string
+	EndpointProto    string
+	EndpointInsecure bool
+	RemotePath       string
+	BucketName       string
+	StorageClass     string
+	PartSize         int64
+	CACert           *x509.Certificate
+}
+
+// NewStorageBackend creates and initializes a new S3/Minio storage backend.
+func NewStorageBackend(opts Config, logFunc storage.Log) (storage.Backend, error) {
+	var creds *credentials.Credentials
+	if opts.AccessKeyID != "" && opts.SecretAccessKey != "" {
+		creds = credentials.NewStaticV4(
+			opts.AccessKeyID,
+			opts.SecretAccessKey,
+			"",
+		)
+	} else if opts.IamRoleEndpoint != "" {
+		creds = credentials.NewIAM(opts.IamRoleEndpoint)
+	} else {
+		return nil, errors.New("NewStorageBackend: AWS_S3_BUCKET_NAME is defined, but no credentials were provided")
+	}
+
+	options := minio.Options{
+		Creds:  creds,
+		Secure: opts.EndpointProto == "https",
+	}
+
+	transport, err := minio.DefaultTransport(true)
+	if err != nil {
+		return nil, fmt.Errorf("NewStorageBackend: failed to create default minio transport: %w", err)
+	}
+
+	if opts.EndpointInsecure {
+		if !options.Secure {
+			return nil, errors.New("NewStorageBackend: AWS_ENDPOINT_INSECURE = true is only meaningful for https")
+		}
+		transport.TLSClientConfig.InsecureSkipVerify = true
+	} else if opts.CACert != nil {
+		if transport.TLSClientConfig.RootCAs == nil {
+			transport.TLSClientConfig.RootCAs = x509.NewCertPool()
+		}
+		transport.TLSClientConfig.RootCAs.AddCert(opts.CACert)
+	}
+	options.Transport = transport
+
+	mc, err := minio.New(opts.Endpoint, &options)
+	if err != nil {
+		return nil, fmt.Errorf("NewStorageBackend: error setting up minio client: %w", err)
+	}
+
+	return &s3Storage{
+		StorageBackend: &storage.StorageBackend{
+			DestinationPath: opts.RemotePath,
+			Log:             logFunc,
+		},
+		client:       mc,
+		bucket:       opts.BucketName,
+		storageClass: opts.StorageClass,
+		partSize:     opts.PartSize,
+	}, nil
+}
+
+// Name returns the name of the storage backend
+func (v *s3Storage) Name() string {
+	return "S3"
+}
+
+// Copy copies the given file to the S3/Minio storage backend.
+func (b *s3Storage) Copy(file string) error {
+	_, name := path.Split(file)
+	putObjectOptions := minio.PutObjectOptions{
+		ContentType:  "application/tar+gzip",
+		StorageClass: b.storageClass,
+	}
+
+	if b.partSize > 0 {
+		srcFileInfo, err := os.Stat(file)
+		if err != nil {
+			return fmt.Errorf("(*s3Storage).Copy: error reading the local file: %w", err)
+		}
+
+		_, partSize, _, err := minio.OptimalPartInfo(srcFileInfo.Size(), uint64(b.partSize*1024*1024))
+		if err != nil {
+			return fmt.Errorf("(*s3Storage).Copy: error computing the optimal s3 part size: %w", err)
+		}
+
+		putObjectOptions.PartSize = uint64(partSize)
+	}
+
+	if _, err := b.client.FPutObject(context.Background(), b.bucket, filepath.Join(b.DestinationPath, name), file, putObjectOptions); err != nil {
+		if errResp := minio.ToErrorResponse(err); errResp.Message != "" {
+			return fmt.Errorf(
+				"(*s3Storage).Copy: error uploading backup to remote storage: [Message]: '%s', [Code]: %s, [StatusCode]: %d",
+				errResp.Message,
+				errResp.Code,
+				errResp.StatusCode,
+			)
+		}
+		return fmt.Errorf("(*s3Storage).Copy: error uploading backup to remote storage: %w", err)
+	}
+
+	b.Log(storage.LogLevelInfo, b.Name(), "Uploaded a copy of backup `%s` to bucket `%s`.", file, b.bucket)
+
+	return nil
+}
+
+// Prune rotates away backups according to the configuration and provided deadline for the S3/Minio storage backend.
+func (b *s3Storage) Prune(deadline time.Time, pruningPrefix string) (*storage.PruneStats, error) {
+	candidates := b.client.ListObjects(context.Background(), b.bucket, minio.ListObjectsOptions{
+		Prefix:    filepath.Join(b.DestinationPath, pruningPrefix),
+		Recursive: true,
+	})
+
+	var matches []minio.ObjectInfo
+	var lenCandidates int
+	for candidate := range candidates {
+		lenCandidates++
+		if candidate.Err != nil {
+			return nil, fmt.Errorf(
+				"(*s3Storage).Prune: error looking up candidates from remote storage! %w",
+				candidate.Err,
+			)
+		}
+		if candidate.LastModified.Before(deadline) {
+			matches = append(matches, candidate)
+		}
+	}
+
+	stats := &storage.PruneStats{
+		Total:  uint(lenCandidates),
+		Pruned: uint(len(matches)),
+	}
+
+	if err := b.DoPrune(b.Name(), len(matches), lenCandidates, func() error {
+		objectsCh := make(chan minio.ObjectInfo)
+		go func() {
+			for _, match := range matches {
+				objectsCh <- match
+			}
+			close(objectsCh)
+		}()
+		errChan := b.client.RemoveObjects(context.Background(), b.bucket, objectsCh, minio.RemoveObjectsOptions{})
+		var removeErrors []error
+		for result := range errChan {
+			if result.Err != nil {
+				removeErrors = append(removeErrors, result.Err)
+			}
+		}
+		if len(removeErrors) != 0 {
+			return errors.Join(removeErrors...)
+		}
+		return nil
+	}); err != nil {
+		return stats, err
+	}
+
+	return stats, nil
+}

internal/storage/ssh/ssh.go

@@ -0,0 +1,189 @@
+// Copyright 2022 - Offen Authors <hioffen@posteo.de>
+// SPDX-License-Identifier: MPL-2.0
+
+package ssh
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/offen/docker-volume-backup/internal/storage"
+	"github.com/pkg/sftp"
+	"golang.org/x/crypto/ssh"
+)
+
+type sshStorage struct {
+	*storage.StorageBackend
+	client     *ssh.Client
+	sftpClient *sftp.Client
+	hostName   string
+}
+
+// Config allows to configure a SSH backend.
+type Config struct {
+	HostName           string
+	Port               string
+	User               string
+	Password           string
+	IdentityFile       string
+	IdentityPassphrase string
+	RemotePath         string
+}
+
+// NewStorageBackend creates and initializes a new SSH storage backend.
+func NewStorageBackend(opts Config, logFunc storage.Log) (storage.Backend, error) {
+	var authMethods []ssh.AuthMethod
+
+	if opts.Password != "" {
+		authMethods = append(authMethods, ssh.Password(opts.Password))
+	}
+
+	if _, err := os.Stat(opts.IdentityFile); err == nil {
+		key, err := os.ReadFile(opts.IdentityFile)
+		if err != nil {
+			return nil, errors.New("NewStorageBackend: error reading the private key")
+		}
+
+		var signer ssh.Signer
+		if opts.IdentityPassphrase != "" {
+			signer, err = ssh.ParsePrivateKeyWithPassphrase(key, []byte(opts.IdentityPassphrase))
+			if err != nil {
+				return nil, errors.New("NewStorageBackend: error parsing the encrypted private key")
+			}
+			authMethods = append(authMethods, ssh.PublicKeys(signer))
+		} else {
+			signer, err = ssh.ParsePrivateKey(key)
+			if err != nil {
+				return nil, errors.New("NewStorageBackend: error parsing the private key")
+			}
+			authMethods = append(authMethods, ssh.PublicKeys(signer))
+		}
+	}
+
+	sshClientConfig := &ssh.ClientConfig{
+		User:            opts.User,
+		Auth:            authMethods,
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
+	}
+	sshClient, err := ssh.Dial("tcp", fmt.Sprintf("%s:%s", opts.HostName, opts.Port), sshClientConfig)
+
+	if err != nil {
+		return nil, fmt.Errorf("NewStorageBackend: error creating ssh client: %w", err)
+	}
+	_, _, err = sshClient.SendRequest("keepalive", false, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	sftpClient, err := sftp.NewClient(sshClient)
+	if err != nil {
+		return nil, fmt.Errorf("NewStorageBackend: error creating sftp client: %w", err)
+	}
+
+	return &sshStorage{
+		StorageBackend: &storage.StorageBackend{
+			DestinationPath: opts.RemotePath,
+			Log:             logFunc,
+		},
+		client:     sshClient,
+		sftpClient: sftpClient,
+		hostName:   opts.HostName,
+	}, nil
+}
+
+// Name returns the name of the storage backend
+func (b *sshStorage) Name() string {
+	return "SSH"
+}
+
+// Copy copies the given file to the SSH storage backend.
+func (b *sshStorage) Copy(file string) error {
+	source, err := os.Open(file)
+	_, name := path.Split(file)
+	if err != nil {
+		return fmt.Errorf("(*sshStorage).Copy: error reading the file to be uploaded: %w", err)
+	}
+	defer source.Close()
+
+	destination, err := b.sftpClient.Create(filepath.Join(b.DestinationPath, name))
+	if err != nil {
+		return fmt.Errorf("(*sshStorage).Copy: error creating file: %w", err)
+	}
+	defer destination.Close()
+
+	chunk := make([]byte, 1000000)
+	for {
+		num, err := source.Read(chunk)
+		if err == io.EOF {
+			tot, err := destination.Write(chunk[:num])
+			if err != nil {
+				return fmt.Errorf("(*sshStorage).Copy: error uploading the file: %w", err)
+			}
+
+			if tot != len(chunk[:num]) {
+				return errors.New("(*sshStorage).Copy: failed to write stream")
+			}
+
+			break
+		}
+
+		if err != nil {
+			return fmt.Errorf("(*sshStorage).Copy: error uploading the file: %w", err)
+		}
+
+		tot, err := destination.Write(chunk[:num])
+		if err != nil {
+			return fmt.Errorf("(*sshStorage).Copy: error uploading the file: %w", err)
+		}
+
+		if tot != len(chunk[:num]) {
+			return fmt.Errorf("(*sshStorage).Copy: failed to write stream")
+		}
+	}
+
+	b.Log(storage.LogLevelInfo, b.Name(), "Uploaded a copy of backup `%s` to '%s' at path '%s'.", file, b.hostName, b.DestinationPath)
+
+	return nil
+}
+
+// Prune rotates away backups according to the configuration and provided deadline for the SSH storage backend.
+func (b *sshStorage) Prune(deadline time.Time, pruningPrefix string) (*storage.PruneStats, error) {
+	candidates, err := b.sftpClient.ReadDir(b.DestinationPath)
+	if err != nil {
+		return nil, fmt.Errorf("(*sshStorage).Prune: error reading directory: %w", err)
+	}
+
+	var matches []string
+	for _, candidate := range candidates {
+		if !strings.HasPrefix(candidate.Name(), pruningPrefix) {
+			continue
+		}
+		if candidate.ModTime().Before(deadline) {
+			matches = append(matches, candidate.Name())
+		}
+	}
+
+	stats := &storage.PruneStats{
+		Total:  uint(len(candidates)),
+		Pruned: uint(len(matches)),
+	}
+
+	if err := b.DoPrune(b.Name(), len(matches), len(candidates), func() error {
+		for _, match := range matches {
+			if err := b.sftpClient.Remove(filepath.Join(b.DestinationPath, match)); err != nil {
+				return fmt.Errorf("(*sshStorage).Prune: error removing file: %w", err)
+			}
+		}
+		return nil
+	}); err != nil {
+		return stats, err
+	}
+
+	return stats, nil
+}

internal/storage/storage.go

@@ -0,0 +1,60 @@
+// Copyright 2022 - Offen Authors <hioffen@posteo.de>
+// SPDX-License-Identifier: MPL-2.0
+
+package storage
+
+import (
+	"time"
+)
+
+// Backend is an interface for defining functions which all storage providers support.
+type Backend interface {
+	Copy(file string) error
+	Prune(deadline time.Time, pruningPrefix string) (*PruneStats, error)
+	Name() string
+}
+
+// StorageBackend is a generic type of storage. Everything here are common properties of all storage types.
+type StorageBackend struct {
+	DestinationPath string
+	RetentionDays   int
+	Log             Log
+}
+
+type LogLevel int
+
+const (
+	LogLevelInfo LogLevel = iota
+	LogLevelWarning
+	LogLevelError
+)
+
+type Log func(logType LogLevel, context string, msg string, params ...any)
+
+// PruneStats is a wrapper struct for returning stats after pruning
+type PruneStats struct {
+	Total  uint
+	Pruned uint
+}
+
+// DoPrune holds general control flow that applies to any kind of storage.
+// Callers can pass in a thunk that performs the actual deletion of files.
+func (b *StorageBackend) DoPrune(context string, lenMatches, lenCandidates int, doRemoveFiles func() error) error {
+	if lenMatches != 0 && lenMatches != lenCandidates {
+		if err := doRemoveFiles(); err != nil {
+			return err
+		}
+		b.Log(LogLevelInfo, context,
+			"Pruned %d out of %d backups as their age exceeded the configured retention period of %d days.",
+			lenMatches,
+			lenCandidates,
+			b.RetentionDays,
+		)
+	} else if lenMatches != 0 && lenMatches == lenCandidates {
+		b.Log(LogLevelWarning, context, "The current configuration would delete all %d existing backups.", lenMatches)
+		b.Log(LogLevelWarning, context, "Refusing to do so, please check your configuration.")
+	} else {
+		b.Log(LogLevelInfo, context, "None of %d existing backups were pruned.", lenCandidates)
+	}
+	return nil
+}

internal/storage/webdav/webdav.go

@@ -0,0 +1,123 @@
+// Copyright 2022 - Offen Authors <hioffen@posteo.de>
+// SPDX-License-Identifier: MPL-2.0
+
+package webdav
+
+import (
+	"errors"
+	"fmt"
+	"io/fs"
+	"net/http"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/offen/docker-volume-backup/internal/storage"
+	"github.com/studio-b12/gowebdav"
+)
+
+type webDavStorage struct {
+	*storage.StorageBackend
+	client *gowebdav.Client
+	url    string
+}
+
+// Config allows to configure a WebDAV storage backend.
+type Config struct {
+	URL         string
+	RemotePath  string
+	Username    string
+	Password    string
+	URLInsecure bool
+}
+
+// NewStorageBackend creates and initializes a new WebDav storage backend.
+func NewStorageBackend(opts Config, logFunc storage.Log) (storage.Backend, error) {
+	if opts.Username == "" || opts.Password == "" {
+		return nil, errors.New("NewStorageBackend: WEBDAV_URL is defined, but no credentials were provided")
+	} else {
+		webdavClient := gowebdav.NewClient(opts.URL, opts.Username, opts.Password)
+
+		if opts.URLInsecure {
+			defaultTransport, ok := http.DefaultTransport.(*http.Transport)
+			if !ok {
+				return nil, errors.New("NewStorageBackend: unexpected error when asserting type for http.DefaultTransport")
+			}
+			webdavTransport := defaultTransport.Clone()
+			webdavTransport.TLSClientConfig.InsecureSkipVerify = opts.URLInsecure
+			webdavClient.SetTransport(webdavTransport)
+		}
+
+		return &webDavStorage{
+			StorageBackend: &storage.StorageBackend{
+				DestinationPath: opts.RemotePath,
+				Log:             logFunc,
+			},
+			client: webdavClient,
+		}, nil
+	}
+}
+
+// Name returns the name of the storage backend
+func (b *webDavStorage) Name() string {
+	return "WebDAV"
+}
+
+// Copy copies the given file to the WebDav storage backend.
+func (b *webDavStorage) Copy(file string) error {
+	_, name := path.Split(file)
+	if err := b.client.MkdirAll(b.DestinationPath, 0644); err != nil {
+		return fmt.Errorf("(*webDavStorage).Copy: error creating directory '%s' on server: %w", b.DestinationPath, err)
+	}
+
+	r, err := os.Open(file)
+	if err != nil {
+		return fmt.Errorf("(*webDavStorage).Copy: error opening the file to be uploaded: %w", err)
+	}
+
+	if err := b.client.WriteStream(filepath.Join(b.DestinationPath, name), r, 0644); err != nil {
+		return fmt.Errorf("(*webDavStorage).Copy: error uploading the file: %w", err)
+	}
+	b.Log(storage.LogLevelInfo, b.Name(), "Uploaded a copy of backup '%s' to '%s' at path '%s'.", file, b.url, b.DestinationPath)
+
+	return nil
+}
+
+// Prune rotates away backups according to the configuration and provided deadline for the WebDav storage backend.
+func (b *webDavStorage) Prune(deadline time.Time, pruningPrefix string) (*storage.PruneStats, error) {
+	candidates, err := b.client.ReadDir(b.DestinationPath)
+	if err != nil {
+		return nil, fmt.Errorf("(*webDavStorage).Prune: error looking up candidates from remote storage: %w", err)
+	}
+	var matches []fs.FileInfo
+	var lenCandidates int
+	for _, candidate := range candidates {
+		if !strings.HasPrefix(candidate.Name(), pruningPrefix) {
+			continue
+		}
+		lenCandidates++
+		if candidate.ModTime().Before(deadline) {
+			matches = append(matches, candidate)
+		}
+	}
+
+	stats := &storage.PruneStats{
+		Total:  uint(lenCandidates),
+		Pruned: uint(len(matches)),
+	}
+
+	if err := b.DoPrune(b.Name(), len(matches), lenCandidates, func() error {
+		for _, match := range matches {
+			if err := b.client.Remove(filepath.Join(b.DestinationPath, match.Name())); err != nil {
+				return fmt.Errorf("(*webDavStorage).Prune: error removing file: %w", err)
+			}
+		}
+		return nil
+	}); err != nil {
+		return stats, err
+	}
+
+	return stats, nil
+}

test/azure/docker-compose.yml

@@ -0,0 +1,58 @@
+version: '3'
+
+services:
+  storage:
+    image: mcr.microsoft.com/azure-storage/azurite
+    volumes:
+      - azurite_backup_data:/data
+    command: azurite-blob --blobHost 0.0.0.0 --blobPort 10000 --location /data
+    healthcheck:
+        test: nc 127.0.0.1 10000 -z
+        interval: 1s
+        retries: 30
+
+  az_cli:
+    image: mcr.microsoft.com/azure-cli
+    volumes:
+      - ./local:/dump
+    command:
+      - /bin/sh
+      - -c
+      - |
+          az storage container create --name test-container
+    depends_on:
+      storage:
+        condition: service_healthy
+    environment:
+      AZURE_STORAGE_CONNECTION_STRING: DefaultEndpointsProtocol=http;AccountName=devstoreaccount1;AccountKey=Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw==;BlobEndpoint=http://storage:10000/devstoreaccount1;
+
+  backup:
+    image: offen/docker-volume-backup:${TEST_VERSION:-canary}
+    hostname: hostnametoken
+    restart: always
+    environment:
+      AZURE_STORAGE_ACCOUNT_NAME: devstoreaccount1
+      AZURE_STORAGE_PRIMARY_ACCOUNT_KEY: Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw==
+      AZURE_STORAGE_CONTAINER_NAME: test-container
+      AZURE_STORAGE_ENDPOINT: http://storage:10000/{{ .AccountName }}/
+      AZURE_STORAGE_PATH: 'path/to/backup'
+      BACKUP_FILENAME: test.tar.gz
+      BACKUP_CRON_EXPRESSION: 0 0 5 31 2 ?
+      BACKUP_RETENTION_DAYS: ${BACKUP_RETENTION_DAYS:-7}
+      BACKUP_PRUNING_LEEWAY: 5s
+      BACKUP_PRUNING_PREFIX: test
+    volumes:
+      - app_data:/backup/app_data:ro
+      - /var/run/docker.sock:/var/run/docker.sock
+
+  offen:
+    image: offen/offen:latest
+    labels:
+      - docker-volume-backup.stop-during-backup=true
+    volumes:
+      - app_data:/var/opt/offen
+
+volumes:
+  azurite_backup_data:
+    name: azurite_backup_data
+  app_data:

test/azure/run.sh

@@ -0,0 +1,66 @@
+#!/bin/sh
+
+set -e
+
+cd "$(dirname "$0")"
+. ../util.sh
+current_test=$(basename $(pwd))
+
+download_az () {
+  docker compose run --rm az_cli \
+    az storage blob download -f /dump/$1.tar.gz -c test-container -n path/to/backup/$1.tar.gz
+}
+
+docker compose up -d --quiet-pull
+sleep 5
+
+docker compose exec backup backup
+
+sleep 5
+
+expect_running_containers "3"
+
+download_az "test"
+tar -xvf ./local/test.tar.gz -C /tmp && test -f /tmp/backup/app_data/offen.db
+
+pass "Found relevant files in untared remote backups."
+
+# The second part of this test checks if backups get deleted when the retention
+# is set to 0 days (which it should not as it would mean all backups get deleted)
+BACKUP_RETENTION_DAYS="0" docker compose up -d
+sleep 5
+
+docker compose exec backup backup
+
+download_az "test"
+test -f ./local/test.tar.gz
+
+pass "Remote backups have not been deleted."
+
+# The third part of this test checks if old backups get deleted when the retention
+# is set to 7 days (which it should)
+
+BACKUP_RETENTION_DAYS="7" docker compose up -d
+sleep 5
+
+info "Create first backup with no prune"
+docker compose exec backup backup
+
+sudo date --set="14 days ago"
+
+docker compose run --rm az_cli \
+    az storage blob upload -f /dump/test.tar.gz -c test-container -n path/to/backup/test-old.tar.gz
+
+sudo date --set="14 days"
+
+info "Create second backup and prune"
+docker compose exec backup backup
+
+info "Download first backup which should be pruned"
+download_az "test-old" || true
+test ! -f ./local/test-old.tar.gz
+test -f ./local/test.tar.gz
+
+pass "Old remote backup has been pruned, new one is still present."
+
+docker compose down --volumes

test/certs/docker-compose.yml

@@ -0,0 +1,48 @@
+version: '3'
+
+services:
+  minio:
+    hostname: minio.local
+    image: minio/minio:RELEASE.2020-08-04T23-10-51Z
+    environment:
+      MINIO_ROOT_USER: test
+      MINIO_ROOT_PASSWORD: test
+      MINIO_ACCESS_KEY: test
+      MINIO_SECRET_KEY: GMusLtUmILge2by+z890kQ
+    entrypoint: /bin/ash -c 'mkdir -p /data/backup && minio server --certs-dir "/certs" --address ":443" /data'
+    volumes:
+      - minio_backup_data:/data
+      - ./minio.crt:/certs/public.crt
+      - ./minio.key:/certs/private.key
+
+  backup:
+    image: offen/docker-volume-backup:${TEST_VERSION:-canary}
+    depends_on:
+      - minio
+    restart: always
+    environment:
+      BACKUP_FILENAME: test.tar.gz
+      AWS_ACCESS_KEY_ID: test
+      AWS_SECRET_ACCESS_KEY: GMusLtUmILge2by+z890kQ
+      AWS_ENDPOINT: minio.local:443
+      AWS_ENDPOINT_CA_CERT: /root/minio-rootCA.crt
+      AWS_S3_BUCKET_NAME: backup
+      BACKUP_CRON_EXPRESSION: 0 0 5 31 2 ?
+      BACKUP_RETENTION_DAYS: ${BACKUP_RETENTION_DAYS:-7}
+      BACKUP_PRUNING_LEEWAY: 5s
+    volumes:
+      - app_data:/backup/app_data:ro
+      - /var/run/docker.sock:/var/run/docker.sock
+      - ./rootCA.crt:/root/minio-rootCA.crt
+
+  offen:
+    image: offen/offen:latest
+    labels:
+      - docker-volume-backup.stop-during-backup=true
+    volumes:
+      - app_data:/var/opt/offen
+
+volumes:
+  minio_backup_data:
+    name: minio_backup_data
+  app_data:

test/certs/run.sh

@@ -0,0 +1,43 @@
+#!/bin/sh
+
+set -e
+
+cd "$(dirname "$0")"
+. ../util.sh
+current_test=$(basename $(pwd))
+
+openssl genrsa -des3 -passout pass:test -out rootCA.key 4096
+openssl req -passin pass:test \
+  -subj "/C=DE/ST=BE/O=IntegrationTest, Inc." \
+  -x509 -new -key rootCA.key -sha256 -days 1 -out rootCA.crt
+
+openssl genrsa -out minio.key 4096
+openssl req -new -sha256 -key minio.key \
+  -subj "/C=DE/ST=BE/O=IntegrationTest, Inc./CN=minio" \
+  -out minio.csr
+
+openssl x509 -req -passin pass:test \
+  -in minio.csr \
+  -CA rootCA.crt -CAkey rootCA.key -CAcreateserial \
+  -extfile san.cnf \
+  -out minio.crt -days 1 -sha256
+
+openssl x509 -in minio.crt -noout -text
+
+docker compose up -d --quiet-pull
+sleep 5
+
+docker compose exec backup backup
+
+sleep 5
+
+expect_running_containers "3"
+
+docker run --rm \
+  -v minio_backup_data:/minio_data \
+  alpine \
+  ash -c 'tar -xvf /minio_data/backup/test.tar.gz -C /tmp && test -f /tmp/backup/app_data/offen.db'
+
+pass "Found relevant files in untared remote backups."
+
+docker compose down --volumes

test/certs/san.cnf

@@ -0,0 +1 @@
+subjectAltName = DNS:minio.local

test/cli/run.sh

@@ -3,6 +3,8 @@
 set -e
 
 cd $(dirname $0)
+. ../util.sh
+current_test=$(basename $(pwd))
 
 docker network create test_network
 docker volume create backup_data
@@ -11,7 +13,7 @@ docker volume create app_data
 # correctly. It is not supposed to hold any data.
 docker volume create empty_data
 
-docker run -d \
+docker run -d -q \
   --name minio \
   --network test_network \
   --env MINIO_ROOT_USER=test \
@@ -23,7 +25,7 @@ docker run -d \
 
 docker exec minio mkdir -p /data/backup
 
-docker run -d \
+docker run -d -q \
   --name offen \
   --network test_network \
   -v app_data:/var/opt/offen/ \
@@ -31,7 +33,7 @@ docker run -d \
 
 sleep 10
 
-docker run --rm \
+docker run --rm -q \
   --network test_network \
   -v app_data:/backup/app_data \
   -v empty_data:/backup/empty_data \
@@ -46,21 +48,15 @@ docker run --rm \
   --entrypoint backup \
   offen/docker-volume-backup:${TEST_VERSION:-canary}
 
-docker run --rm -it \
+docker run --rm -q \
   -v backup_data:/data alpine \
   ash -c 'tar -xvf /data/backup/test.tar.gz && test -f /backup/app_data/offen.db && test -d /backup/empty_data'
 
-echo "[TEST:PASS] Found relevant files in untared remote backup."
+pass "Found relevant files in untared remote backup."
 
 # This test does not stop containers during backup. This is happening on
 # purpose in order to cover this setup as well.
-if [ "$(docker ps -q | wc -l)" != "2" ]; then
+expect_running_containers "2"
-  echo "[TEST:FAIL] Expected all containers to be running post backup, instead seen:"
-  docker ps
-  exit 1
-fi
-
-echo "[TEST:PASS] All containers running post backup."
 
 docker rm $(docker stop minio offen)
 docker volume rm backup_data app_data

test/commands/docker-compose.yml

@@ -10,12 +10,27 @@ services:
       MARIADB_ROOT_PASSWORD: test
       MARIADB_DATABASE: backup
     labels:
+      # this is testing the deprecated label on purpose
       - docker-volume-backup.exec-pre=/bin/sh -c 'mysqldump -ptest --all-databases > /tmp/volume/dump.sql'
-      - docker-volume-backup.exec-post=/bin/sh -c 'echo "post" > /tmp/volume/post.txt'
+      - docker-volume-backup.copy-post=/bin/sh -c 'echo "post" > /tmp/volume/post.txt'
       - docker-volume-backup.exec-label=test
     volumes:
       - app_data:/tmp/volume
 
+  other_database:
+    image: mariadb:10.7
+    deploy:
+      restart_policy:
+        condition: on-failure
+    environment:
+      MARIADB_ROOT_PASSWORD: test
+      MARIADB_DATABASE: backup
+    labels:
+      - docker-volume-backup.archive-pre=touch /tmp/volume/not-relevant.txt
+      - docker-volume-backup.exec-label=not-relevant
+    volumes:
+      - app_data:/tmp/volume
+
   backup:
     image: offen/docker-volume-backup:${TEST_VERSION:-canary}
     deploy:
@@ -27,10 +42,9 @@ services:
       EXEC_LABEL: test
       EXEC_FORWARD_OUTPUT: "true"
     volumes:
-      - archive:/archive
+      - ./local:/archive
       - app_data:/backup/data:ro
       - /var/run/docker.sock:/var/run/docker.sock
 
 volumes:
   app_data:
-  archive:

test/commands/run.sh

@@ -3,39 +3,45 @@
 set -e
 
 cd $(dirname $0)
+. ../util.sh
+current_test=$(basename $(pwd))
 
+mkdir -p ./local
 
-docker-compose up -d
+docker compose up -d --quiet-pull
 sleep 30 # mariadb likes to take a bit before responding
 
-docker-compose exec backup backup
+docker compose exec backup backup
-sudo cp -r $(docker volume inspect --format='{{ .Mountpoint }}' commands_archive) ./local
 
 tar -xvf ./local/test.tar.gz
 if [ ! -f ./backup/data/dump.sql ]; then
-  echo "[TEST:FAIL] Could not find file written by pre command."
+  fail "Could not find file written by pre command."
-  exit 1
 fi
-echo "[TEST:PASS] Found expected file."
+pass "Found expected file."
+
+if [ -f ./backup/data/not-relevant.txt ]; then
+  fail "Command ran for container with other label."
+fi
+pass "Command did not run for container with other label."
 
 if [ -f ./backup/data/post.txt ]; then
-  echo "[TEST:FAIL] File created in post command was present in backup."
+  fail "File created in post command was present in backup."
-  exit 1
 fi
-echo "[TEST:PASS] Did not find unexpected file."
+pass "Did not find unexpected file."
 
-docker-compose down --volumes
+docker compose down --volumes
 sudo rm -rf ./local
 
 
-echo "[TEST:INFO] Running commands test in swarm mode next."
+info "Running commands test in swarm mode next."
 
+mkdir -p ./local
 docker swarm init
 
 docker stack deploy --compose-file=docker-compose.yml test_stack
 
 while [ -z $(docker ps -q -f name=backup) ]; do
-  echo "[TEST:INFO] Backup container not ready yet. Retrying."
+  info "Backup container not ready yet. Retrying."
   sleep 1
 done
 
@@ -43,20 +49,16 @@ sleep 20
 
 docker exec $(docker ps -q -f name=backup) backup
 
-sudo cp -r $(docker volume inspect --format='{{ .Mountpoint }}' test_stack_archive) ./local
-
 tar -xvf ./local/test.tar.gz
 if [ ! -f ./backup/data/dump.sql ]; then
-  echo "[TEST:FAIL] Could not find file written by pre command."
+  fail "Could not find file written by pre command."
-  exit 1
 fi
-echo "[TEST:PASS] Found expected file."
+pass "Found expected file."
 
 if [ -f ./backup/data/post.txt ]; then
-  echo "[TEST:FAIL] File created in post command was present in backup."
+  fail "File created in post command was present in backup."
-  exit 1
 fi
-echo "[TEST:PASS] Did not find unexpected file."
+pass "Did not find unexpected file."
 
 docker stack rm test_stack
 docker swarm leave --force

test/compose/run.sh

@@ -1,68 +0,0 @@
-#!/bin/sh
-
-set -e
-
-cd $(dirname $0)
-
-mkdir -p local
-
-docker-compose up -d
-sleep 5
-
-# A symlink for a known file in the volume is created so the test can check
-# whether symlinks are preserved on backup.
-docker-compose exec offen ln -s /var/opt/offen/offen.db /var/opt/offen/db.link
-docker-compose exec backup backup
-
-sleep 5
-if [ "$(docker-compose ps -q | wc -l)" != "4" ]; then
-  echo "[TEST:FAIL] Expected all containers to be running post backup, instead seen:"
-  docker-compose ps
-  exit 1
-fi
-echo "[TEST:PASS] All containers running post backup."
-
-
-docker run --rm -it \
-  -v compose_minio_backup_data:/minio_data \
-  -v compose_webdav_backup_data:/webdav_data alpine \
-  ash -c 'apk add gnupg && \
-          echo 1234secret | gpg -d --pinentry-mode loopback --passphrase-fd 0 --yes /minio_data/backup/test-hostnametoken.tar.gz.gpg > /tmp/test-hostnametoken.tar.gz && tar -xvf /tmp/test-hostnametoken.tar.gz -C /tmp && test -f /tmp/backup/app_data/offen.db && \
-          echo 1234secret | gpg -d --pinentry-mode loopback --passphrase-fd 0 --yes /webdav_data/data/my/new/path/test-hostnametoken.tar.gz.gpg > /tmp/test-hostnametoken.tar.gz && tar -xvf /tmp/test-hostnametoken.tar.gz -C /tmp && test -f /tmp/backup/app_data/offen.db'
-
-echo "[TEST:PASS] Found relevant files in decrypted and untared remote backups."
-
-echo 1234secret | gpg -d --pinentry-mode loopback --yes --passphrase-fd 0 ./local/test-hostnametoken.tar.gz.gpg > ./local/decrypted.tar.gz
-tar -xf ./local/decrypted.tar.gz -C /tmp && test -f /tmp/backup/app_data/offen.db
-rm ./local/decrypted.tar.gz
-test -L /tmp/backup/app_data/db.link
-
-echo "[TEST:PASS] Found relevant files in decrypted and untared local backup."
-
-test -L ./local/test-hostnametoken.latest.tar.gz.gpg
-echo "[TEST:PASS] Found symlink to latest version in local backup."
-
-# The second part of this test checks if backups get deleted when the retention
-# is set to 0 days (which it should not as it would mean all backups get deleted)
-# TODO: find out if we can test actual deletion without having to wait for a day
-BACKUP_RETENTION_DAYS="0" docker-compose up -d
-sleep 5
-
-docker-compose exec backup backup
-
-docker run --rm -it \
-  -v compose_minio_backup_data:/minio_data \
-  -v compose_webdav_backup_data:/webdav_data alpine \
-  ash -c '[ $(find /minio_data/backup/ -type f | wc -l) = "1" ] && \
-          [ $(find /webdav_data/data/my/new/path/ -type f | wc -l) = "1" ]'
-
-echo "[TEST:PASS] Remote backups have not been deleted."
-
-if [ "$(find ./local -type f | wc -l)" != "1" ]; then
-  echo "[TEST:FAIL] Backups should not have been deleted, instead seen:"
-  find ./local -type f
-  exit 1
-fi
-echo "[TEST:PASS] Local backups have not been deleted."
-
-docker-compose down --volumes

test/confd/run.sh

@@ -3,30 +3,29 @@
 set -e
 
 cd $(dirname $0)
+. ../util.sh
+current_test=$(basename $(pwd))
 
 mkdir -p local
 
-docker-compose up -d
+docker compose up -d --quiet-pull
 
 # sleep until a backup is guaranteed to have happened on the 1 minute schedule
 sleep 100
 
-docker-compose down --volumes
+docker compose down --volumes
 
 if [ ! -f ./local/conf.tar.gz ]; then
-  echo "[TEST:FAIL] Config from file was not used."
+  fail "Config from file was not used."
-  exit 1
 fi
-echo "[TEST:PASS] Config from file was used."
+pass "Config from file was used."
 
 if [ ! -f ./local/other.tar.gz ]; then
-  echo "[TEST:FAIL] Run on same schedule did not succeed."
+  fail "Run on same schedule did not succeed."
-  exit 1
 fi
-echo "[TEST:PASS] Run on same schedule succeeded."
+pass "Run on same schedule succeeded."
 
 if [ -f ./local/never.tar.gz ]; then
-  echo "[TEST:FAIL] Unexpected file was found."
+  fail "Unexpected file was found."
-  exit 1
 fi
-echo "[TEST:PASS] Unexpected cron did not run."
+pass "Unexpected cron did not run."

test/dropbox/.gitignore

@@ -0,0 +1 @@
+user_v2_ready.yaml

test/dropbox/docker-compose.yml

@@ -0,0 +1,57 @@
+version: '3'
+
+services:
+  openapi_mock:
+    image: muonsoft/openapi-mock:0.3.9
+    environment:
+      OPENAPI_MOCK_USE_EXAMPLES: if_present
+      OPENAPI_MOCK_SPECIFICATION_URL: '/etc/openapi/user_v2.yaml'
+    ports:
+      - 8080:8080
+    volumes:
+      - ./user_v2_ready.yaml:/etc/openapi/user_v2.yaml
+
+  oauth2_mock:
+    image: ghcr.io/navikt/mock-oauth2-server:1.0.0
+    ports:
+      - 8090:8090
+    environment:
+      PORT: 8090
+      JSON_CONFIG_PATH: '/etc/oauth2/config.json'
+    volumes:
+      - ./oauth2_config.json:/etc/oauth2/config.json
+
+  backup:
+    image: offen/docker-volume-backup:${TEST_VERSION:-canary}
+    hostname: hostnametoken
+    depends_on:
+      - openapi_mock
+      - oauth2_mock
+    restart: always
+    environment:
+      BACKUP_FILENAME_EXPAND: 'true'
+      BACKUP_FILENAME: test-$$HOSTNAME.tar.gz
+      BACKUP_CRON_EXPRESSION: 0 0 5 31 2 ?
+      BACKUP_RETENTION_DAYS: ${BACKUP_RETENTION_DAYS:-7}
+      BACKUP_PRUNING_LEEWAY: 5s
+      BACKUP_PRUNING_PREFIX: test
+      DROPBOX_ENDPOINT: http://openapi_mock:8080
+      DROPBOX_OAUTH2_ENDPOINT: http://oauth2_mock:8090
+      DROPBOX_REFRESH_TOKEN: test
+      DROPBOX_APP_KEY: test
+      DROPBOX_APP_SECRET: test
+      DROPBOX_REMOTE_PATH: /test
+      DROPBOX_CONCURRENCY_LEVEL: 6
+    volumes:
+      - app_data:/backup/app_data:ro
+      - /var/run/docker.sock:/var/run/docker.sock
+
+  offen:
+    image: offen/offen:latest
+    labels:
+      - docker-volume-backup.stop-during-backup=true
+    volumes:
+      - app_data:/var/opt/offen
+
+volumes:
+  app_data:

test/dropbox/oauth2_config.json

@@ -0,0 +1,37 @@
+{
+   "interactiveLogin": true,
+   "httpServer": "NettyWrapper",
+   "tokenCallbacks": [
+       {
+           "issuerId": "issuer1",
+           "tokenExpiry": 120,
+           "requestMappings": [
+               {
+                   "requestParam": "scope",
+                   "match": "scope1",
+                   "claims": {
+                       "sub": "subByScope",
+                       "aud": [
+                           "audByScope"
+                       ]
+                   }
+               }
+           ]
+       },
+       {
+           "issuerId": "issuer2",
+           "requestMappings": [
+               {
+                   "requestParam": "someparam",
+                   "match": "somevalue",
+                   "claims": {
+                       "sub": "subBySomeParam",
+                       "aud": [
+                           "audBySomeParam"
+                       ]
+                   }
+               }
+           ]
+       }
+   ]
+}

test/dropbox/run.sh

@@ -0,0 +1,65 @@
+#!/bin/sh
+
+set -e
+
+cd "$(dirname "$0")"
+. ../util.sh
+current_test=$(basename $(pwd))
+
+cp user_v2.yaml user_v2_ready.yaml
+sudo sed -i 's/SERVER_MODIFIED_1/'"$(date "+%Y-%m-%dT%H:%M:%SZ")/g" user_v2_ready.yaml
+sudo sed -i 's/SERVER_MODIFIED_2/'"$(date "+%Y-%m-%dT%H:%M:%SZ" -d "14 days ago")/g" user_v2_ready.yaml
+
+docker compose up -d --quiet-pull
+sleep 5
+
+logs=$(docker compose exec -T backup backup)
+
+sleep 5
+
+expect_running_containers "4"
+
+echo "$logs"
+if echo "$logs" | grep -q "ERROR"; then
+  fail "Backup failed, errors reported: $logs"
+else
+  pass "Backup succeeded, no errors reported."
+fi
+
+# The second part of this test checks if backups get deleted when the retention
+# is set to 0 days (which it should not as it would mean all backups get deleted)
+BACKUP_RETENTION_DAYS="0" docker compose up -d
+sleep 5
+
+logs=$(docker compose exec -T backup backup)
+
+echo "$logs"
+if echo "$logs" | grep -q "Refusing to do so, please check your configuration"; then
+  pass "Remote backups have not been deleted."
+else
+  fail "Remote backups would have been deleted: $logs"
+fi
+
+# The third part of this test checks if old backups get deleted when the retention
+# is set to 7 days (which it should)
+
+BACKUP_RETENTION_DAYS="7" docker compose up -d
+sleep 5
+
+info "Create second backup and prune"
+logs=$(docker compose exec -T backup backup)
+
+echo "$logs"
+if echo "$logs" | grep -q "Pruned 1 out of 2 backups as their age exceeded the configured retention period"; then
+  pass "Old remote backup has been pruned, new one is still present."
+elif echo "$logs" | grep -q "ERROR"; then
+  fail "Pruning failed, errors reported: $logs"
+elif echo "$logs" | grep -q "None of 1 existing backups were pruned"; then
+  fail "Pruning failed, old backup has not been pruned: $logs"
+else
+  fail "Pruning failed, unknown result: $logs"
+fi
+
+
+docker compose down --volumes
+rm user_v2_ready.yaml

test/extend/Dockerfile

@@ -0,0 +1,4 @@
+ARG version=canary
+FROM offen/docker-volume-backup:$version
+
+RUN apk add rsync

test/extend/docker-compose.yml

@@ -0,0 +1,26 @@
+version: '3'
+
+services:
+  backup:
+    image: offen/docker-volume-backup:${TEST_VERSION:-canary}
+    restart: always
+    labels:
+      - docker-volume-backup.copy-post=/bin/sh -c 'mkdir -p /tmp/unpack && tar -xvf $$COMMAND_RUNTIME_ARCHIVE_FILEPATH -C /tmp/unpack && rsync -r /tmp/unpack/backup/app_data /local'
+    environment:
+      BACKUP_FILENAME: test.tar.gz
+      BACKUP_CRON_EXPRESSION: 0 0 5 31 2 ?
+      EXEC_FORWARD_OUTPUT: "true"
+    volumes:
+      - ./local:/local
+      - app_data:/backup/app_data:ro
+      - /var/run/docker.sock:/var/run/docker.sock
+
+  offen:
+    image: offen/offen:latest
+    labels:
+      - docker-volume-backup.stop-during-backup=true
+    volumes:
+      - app_data:/var/opt/offen
+
+volumes:
+  app_data:

test/extend/run.sh

@@ -0,0 +1,29 @@
+#!/bin/sh
+
+set -e
+
+cd "$(dirname "$0")"
+. ../util.sh
+current_test=$(basename $(pwd))
+
+mkdir -p local
+
+export BASE_VERSION="${TEST_VERSION:-canary}"
+export TEST_VERSION="${TEST_VERSION:-canary}-with-rsync"
+
+docker build . -t offen/docker-volume-backup:$TEST_VERSION --build-arg version=$BASE_VERSION
+
+docker compose up -d --quiet-pull
+sleep 5
+
+docker compose exec backup backup
+
+sleep 5
+
+expect_running_containers "2"
+
+if [ ! -f "./local/app_data/offen.db" ]; then
+  fail "Could not find expected file in untared archive."
+fi
+
+docker compose down --volumes

test/gpg/docker-compose.yml

@@ -0,0 +1,26 @@
+version: '3'
+
+services:
+  backup:
+    image: offen/docker-volume-backup:${TEST_VERSION:-canary}
+    restart: always
+    environment:
+      BACKUP_CRON_EXPRESSION: 0 0 5 31 2 ?
+      BACKUP_FILENAME: test.tar.gz
+      BACKUP_LATEST_SYMLINK: test-latest.tar.gz.gpg
+      BACKUP_RETENTION_DAYS: ${BACKUP_RETENTION_DAYS:-7}
+      GPG_PASSPHRASE: 1234#$$ecret
+    volumes:
+      - ./local:/archive
+      - app_data:/backup/app_data:ro
+      - /var/run/docker.sock:/var/run/docker.sock
+
+  offen:
+    image: offen/offen:latest
+    labels:
+      - docker-volume-backup.stop-during-backup=true
+    volumes:
+      - app_data:/var/opt/offen
+
+volumes:
+  app_data:

test/gpg/run.sh

@@ -0,0 +1,33 @@
+#!/bin/sh
+
+set -e
+
+cd "$(dirname "$0")"
+. ../util.sh
+current_test=$(basename $(pwd))
+
+mkdir -p local
+
+docker compose up -d --quiet-pull
+sleep 5
+
+docker compose exec backup backup
+
+expect_running_containers "2"
+
+tmp_dir=$(mktemp -d)
+
+echo "1234#\$ecret" | gpg -d --pinentry-mode loopback --yes --passphrase-fd 0 ./local/test.tar.gz.gpg > ./local/decrypted.tar.gz
+tar -xf ./local/decrypted.tar.gz -C $tmp_dir
+if [ ! -f $tmp_dir/backup/app_data/offen.db ]; then
+  fail "Could not find expected file in untared archive."
+fi
+rm ./local/decrypted.tar.gz
+
+pass "Found relevant files in decrypted and untared local backup."
+
+if [ ! -L ./local/test-latest.tar.gz.gpg ]; then
+  fail "Could not find local symlink to latest encrypted backup."
+fi
+
+docker compose down --volumes

test/ignore/run.sh

@@ -3,25 +3,26 @@
 set -e
 
 cd $(dirname $0)
+. ../util.sh
+current_test=$(basename $(pwd))
+
 mkdir -p local
 
-docker-compose up -d
+docker compose up -d --quiet-pull
 sleep 5
-docker-compose exec backup backup
+docker compose exec backup backup
 
-docker-compose down --volumes
+docker compose down --volumes
 
 out=$(mktemp -d)
 sudo tar --same-owner -xvf ./local/test.tar.gz -C "$out"
 
 if [ ! -f "$out/backup/data/me.txt" ]; then
-  echo "[TEST:FAIL] Expected file was not found."
+  fail "Expected file was not found."
-  exit 1
 fi
-echo "[TEST:PASS] Expected file was found."
+pass "Expected file was found."
 
 if [ -f "$out/backup/data/skip.me" ]; then
-  echo "[TEST:FAIL] Ignored file was found."
+  fail "Ignored file was found."
-  exit 1
 fi
-echo "[TEST:PASS] Ignored file was not found."
+pass "Ignored file was not found."

test/local/.gitignore

@@ -0,0 +1 @@
+local

test/local/docker-compose.yml

@@ -0,0 +1,29 @@
+version: '3'
+
+services:
+  backup:
+    image: offen/docker-volume-backup:${TEST_VERSION:-canary}
+    hostname: hostnametoken
+    restart: always
+    environment:
+      BACKUP_FILENAME_EXPAND: 'true'
+      BACKUP_FILENAME: test-$$HOSTNAME.tar.gz
+      BACKUP_LATEST_SYMLINK: test-$$HOSTNAME.latest.tar.gz.gpg
+      BACKUP_CRON_EXPRESSION: 0 0 5 31 2 ?
+      BACKUP_RETENTION_DAYS: ${BACKUP_RETENTION_DAYS:-7}
+      BACKUP_PRUNING_LEEWAY: 5s
+      BACKUP_PRUNING_PREFIX: test
+    volumes:
+      - app_data:/backup/app_data:ro
+      - /var/run/docker.sock:/var/run/docker.sock
+      - ./local:/archive
+
+  offen:
+    image: offen/offen:latest
+    labels:
+      - docker-volume-backup.stop-during-backup=true
+    volumes:
+      - app_data:/var/opt/offen
+
+volumes:
+  app_data:

test/local/run.sh

@@ -0,0 +1,73 @@
+#!/bin/sh
+
+set -e
+
+cd "$(dirname "$0")"
+. ../util.sh
+current_test=$(basename $(pwd))
+
+mkdir -p local
+
+docker compose up -d --quiet-pull
+sleep 5
+
+# A symlink for a known file in the volume is created so the test can check
+# whether symlinks are preserved on backup.
+docker compose exec offen ln -s /var/opt/offen/offen.db /var/opt/offen/db.link
+docker compose exec backup backup
+
+sleep 5
+
+expect_running_containers "2"
+
+tmp_dir=$(mktemp -d)
+tar -xvf ./local/test-hostnametoken.tar.gz -C $tmp_dir
+if [ ! -f "$tmp_dir/backup/app_data/offen.db" ]; then
+  fail "Could not find expected file in untared archive."
+fi
+rm -f ./local/test-hostnametoken.tar.gz
+
+if [ ! -L "$tmp_dir/backup/app_data/db.link" ]; then
+  fail "Could not find expected symlink in untared archive."
+fi
+
+pass "Found relevant files in decrypted and untared local backup."
+
+if [ ! -L ./local/test-hostnametoken.latest.tar.gz.gpg ]; then
+  fail "Could not find symlink to latest version."
+fi
+
+pass "Found symlink to latest version in local backup."
+
+# The second part of this test checks if backups get deleted when the retention
+# is set to 0 days (which it should not as it would mean all backups get deleted)
+BACKUP_RETENTION_DAYS="0" docker compose up -d
+sleep 5
+
+docker compose exec backup backup
+
+if [ "$(find ./local -type f | wc -l)" != "1" ]; then
+  fail "Backups should not have been deleted, instead seen: "$(find ./local -type f)""
+fi
+pass "Local backups have not been deleted."
+
+# The third part of this test checks if old backups get deleted when the retention
+# is set to 7 days (which it should)
+
+BACKUP_RETENTION_DAYS="7" docker compose up -d
+sleep 5
+
+info "Create first backup with no prune"
+docker compose exec backup backup
+
+touch -r ./local/test-hostnametoken.tar.gz -d "14 days ago" ./local/test-hostnametoken-old.tar.gz
+
+info "Create second backup and prune"
+docker compose exec backup backup
+
+test ! -f ./local/test-hostnametoken-old.tar.gz
+test -f ./local/test-hostnametoken.tar.gz
+
+pass "Old remote backup has been pruned, new one is still present."
+
+docker compose down --volumes

test/notifications/docker-compose.yml

@@ -10,6 +10,7 @@ services:
       BACKUP_PRUNING_PREFIX: test
       NOTIFICATION_LEVEL: info
       NOTIFICATION_URLS: ${NOTIFICATION_URLS}
+      EXTRA_VALUE: extra-value
     volumes:
       - ./local:/archive
       - app_data:/backup/app_data:ro

test/notifications/notifications.tmpl

@@ -1,5 +1,5 @@
 {{ define "title_success" -}}
-Successful test run, yay!
+Successful test run with {{ env "EXTRA_VALUE" }}, yay!
 {{- end }}
 
 {{ define "body_success" -}}

test/notifications/run.sh

@@ -3,50 +3,48 @@
 set -e
 
 cd $(dirname $0)
+. ../util.sh
+current_test=$(basename $(pwd))
 
 mkdir -p local
 
-docker-compose up -d
+docker compose up -d --quiet-pull
 sleep 5
 
 GOTIFY_TOKEN=$(curl -sSLX POST -H 'Content-Type: application/json' -d '{"name":"test"}' http://admin:custom@localhost:8080/application | jq -r '.token')
-echo "[TEST:INFO] Set up Gotify application using token $GOTIFY_TOKEN"
+info "Set up Gotify application using token $GOTIFY_TOKEN"
 
-docker-compose exec backup backup
+docker compose exec backup backup
 
 NUM_MESSAGES=$(curl -sSL http://admin:custom@localhost:8080/message | jq -r '.messages | length')
 if [ "$NUM_MESSAGES" != 0 ]; then
-  echo "[TEST:FAIL] Expected no notifications to be sent when not configured"
+  fail "Expected no notifications to be sent when not configured"
-  exit 1
 fi
-echo "[TEST:PASS] No notifications were sent when not configured."
+pass "No notifications were sent when not configured."
 
-docker-compose down
+docker compose down
 
-NOTIFICATION_URLS="gotify://gotify/${GOTIFY_TOKEN}?disableTLS=true" docker-compose up -d
+NOTIFICATION_URLS="gotify://gotify/${GOTIFY_TOKEN}?disableTLS=true" docker compose up -d
 
-docker-compose exec backup backup
+docker compose exec backup backup
 
 NUM_MESSAGES=$(curl -sSL http://admin:custom@localhost:8080/message | jq -r '.messages | length')
 if [ "$NUM_MESSAGES" != 1 ]; then
-  echo "[TEST:FAIL] Expected one notifications to be sent when configured"
+  fail "Expected one notifications to be sent when configured"
-  exit 1
 fi
-echo "[TEST:PASS] Correct number of notifications were sent when configured."
+pass "Correct number of notifications were sent when configured."
 
 MESSAGE_TITLE=$(curl -sSL http://admin:custom@localhost:8080/message | jq -r '.messages[0].title')
 MESSAGE_BODY=$(curl -sSL http://admin:custom@localhost:8080/message | jq -r '.messages[0].message')
 
-if [ "$MESSAGE_TITLE" != "Successful test run, yay!" ]; then
+if [ "$MESSAGE_TITLE" != "Successful test run with extra-value, yay!" ]; then
-  echo "[TEST:FAIL] Unexpected notification title $MESSAGE_TITLE"
+  fail "Unexpected notification title $MESSAGE_TITLE"
-  exit 1
 fi
-echo "[TEST:PASS] Custom notification title was used."
+pass "Custom notification title was used."
 
 if [ "$MESSAGE_BODY" != "Backing up /tmp/test.tar.gz succeeded." ]; then
-  echo "[TEST:FAIL] Unexpected notification body $MESSAGE_BODY"
+  fail "Unexpected notification body $MESSAGE_BODY"
-  exit 1
 fi
-echo "[TEST:PASS] Custom notification body was used."
+pass "Custom notification body was used."
 
-docker-compose down --volumes
+docker compose down --volumes

test/ownership/run.sh

@@ -4,25 +4,27 @@
 set -e
 
 cd $(dirname $0)
+. ../util.sh
+current_test=$(basename $(pwd))
 
 mkdir -p local
 
-docker-compose up -d
+docker compose up -d --quiet-pull
 sleep 5
 
-docker-compose exec backup backup
+docker compose exec backup backup
 
-sudo tar --same-owner -xvf ./local/backup.tar.gz -C /tmp
+tmp_dir=$(mktemp -d)
+sudo tar --same-owner -xvf ./local/backup.tar.gz -C $tmp_dir
 
-sudo find /tmp/backup/postgres > /dev/null
+sudo find $tmp_dir/backup/postgres > /dev/null
-echo "[TEST:PASS] Backup contains files at expected location"
+pass "Backup contains files at expected location"
 
-for file in $(sudo find /tmp/backup/postgres); do
+for file in $(sudo find $tmp_dir/backup/postgres); do
   if [ "$(sudo stat -c '%u:%g' $file)" != "70:70" ]; then
-    echo "[TEST:FAIL] Unexpected file ownership for $file: $(sudo stat -c '%u:%g' $file)"
+    fail "Unexpected file ownership for $file: $(sudo stat -c '%u:%g' $file)"
-    exit 1
   fi
 done
-echo "[TEST:PASS] All files and directories in backup preserved their ownership."
+pass "All files and directories in backup preserved their ownership."
 
-docker-compose down --volumes
+docker compose down --volumes

test/pruning/docker-compose.yml

@@ -0,0 +1,50 @@
+version: '3'
+
+services:
+  minio:
+    image: minio/minio:RELEASE.2020-08-04T23-10-51Z
+    environment:
+      MINIO_ROOT_USER: test
+      MINIO_ROOT_PASSWORD: test
+      MINIO_ACCESS_KEY: test
+      MINIO_SECRET_KEY: GMusLtUmILge2by+z890kQ
+    entrypoint: /bin/ash -c 'mkdir -p /data/backup && minio server /data'
+    volumes:
+      - minio_backup_data:/data
+
+  backup:
+    image: offen/docker-volume-backup:${TEST_VERSION:-canary}
+    hostname: hostnametoken
+    depends_on:
+      - minio
+    restart: always
+    environment:
+      AWS_ACCESS_KEY_ID: test
+      AWS_SECRET_ACCESS_KEY: GMusLtUmILge2by+z890kQ
+      AWS_ENDPOINT: minio:9000
+      AWS_ENDPOINT_PROTO: http
+      AWS_S3_BUCKET_NAME: backup
+      BACKUP_FILENAME_EXPAND: 'true'
+      BACKUP_FILENAME: test-$$HOSTNAME.tar.gz
+      BACKUP_CRON_EXPRESSION: 0 0 5 31 2 ?
+      BACKUP_RETENTION_DAYS: 7
+      BACKUP_PRUNING_LEEWAY: 5s
+      BACKUP_PRUNING_PREFIX: test
+      BACKUP_LATEST_SYMLINK: test-$$HOSTNAME.latest.tar.gz
+      BACKUP_SKIP_BACKENDS_FROM_PRUNE: 's3'
+    volumes:
+      - app_data:/backup/app_data:ro
+      - /var/run/docker.sock:/var/run/docker.sock
+      - ./local:/archive
+
+  offen:
+    image: offen/offen:latest
+    labels:
+      - docker-volume-backup.stop-during-backup=true
+    volumes:
+      - app_data:/var/opt/offen
+
+volumes:
+  app_data:
+  minio_backup_data:
+    name: minio_backup_data

test/pruning/run.sh

@@ -0,0 +1,70 @@
+#!/bin/sh
+
+# Tests prune-skipping with multiple backends (local, s3)
+# Pruning itself is tested individually for each storage backend
+
+set -e
+
+cd "$(dirname "$0")"
+. ../util.sh
+current_test=$(basename $(pwd))
+
+mkdir -p local
+
+docker compose up -d --quiet-pull
+sleep 5
+
+docker compose exec backup backup
+
+sleep 5
+
+expect_running_containers "3"
+
+touch -r ./local/test-hostnametoken.tar.gz -d "14 days ago" ./local/test-hostnametoken-old.tar.gz
+
+docker run --rm \
+  -v minio_backup_data:/minio_data \
+  alpine \
+  ash -c 'touch -d@$(( $(date +%s) - 1209600 )) /minio_data/backup/test-hostnametoken-old.tar.gz'
+
+# Skip s3 backend from prune
+
+docker compose up -d
+sleep 5
+
+info "Create backup with no prune for s3 backend"
+docker compose exec backup backup
+
+info "Check if old backup has been pruned (local)"
+test ! -f ./local/test-hostnametoken-old.tar.gz
+
+info "Check if old backup has NOT been pruned (s3)"
+docker run --rm \
+  -v minio_backup_data:/minio_data \
+  alpine \
+  ash -c 'test -f /minio_data/backup/test-hostnametoken-old.tar.gz'
+
+pass "Old remote backup has been pruned locally, skipped S3 backend is untouched."
+
+# Skip local and s3 backend from prune (all backends)
+
+touch -r ./local/test-hostnametoken.tar.gz -d "14 days ago" ./local/test-hostnametoken-old.tar.gz
+
+docker compose up -d
+sleep 5
+
+info "Create backup with no prune for both backends"
+docker compose exec -e BACKUP_SKIP_BACKENDS_FROM_PRUNE="s3,local" backup backup
+
+info "Check if old backup has NOT been pruned (local)"
+test -f ./local/test-hostnametoken-old.tar.gz
+
+info "Check if old backup has NOT been pruned (s3)"
+docker run --rm \
+  -v minio_backup_data:/minio_data \
+  alpine \
+  ash -c 'test -f /minio_data/backup/test-hostnametoken-old.tar.gz'
+
+pass "Skipped all backends while pruning."
+
+docker compose down --volumes

test/s3/docker-compose.yml

@@ -12,21 +12,11 @@ services:
     volumes:
       - minio_backup_data:/data
 
-  webdav:
-    image: bytemark/webdav:2.4
-    environment:
-      AUTH_TYPE: Digest
-      USERNAME: test
-      PASSWORD: test
-    volumes:
-      - webdav_backup_data:/var/lib/dav
-
   backup:
     image: offen/docker-volume-backup:${TEST_VERSION:-canary}
     hostname: hostnametoken
     depends_on:
       - minio
-      - webdav
     restart: always
     environment:
       AWS_ACCESS_KEY_ID: test
@@ -36,19 +26,11 @@ services:
       AWS_S3_BUCKET_NAME: backup
       BACKUP_FILENAME_EXPAND: 'true'
       BACKUP_FILENAME: test-$$HOSTNAME.tar.gz
-      BACKUP_LATEST_SYMLINK: test-$$HOSTNAME.latest.tar.gz.gpg
       BACKUP_CRON_EXPRESSION: 0 0 5 31 2 ?
       BACKUP_RETENTION_DAYS: ${BACKUP_RETENTION_DAYS:-7}
       BACKUP_PRUNING_LEEWAY: 5s
       BACKUP_PRUNING_PREFIX: test
-      GPG_PASSPHRASE: 1234secret
-      WEBDAV_URL: http://webdav/
-      WEBDAV_URL_INSECURE: 'true'
-      WEBDAV_PATH: /my/new/path/
-      WEBDAV_USERNAME: test
-      WEBDAV_PASSWORD: test
     volumes:
-      - ./local:/archive
       - app_data:/backup/app_data:ro
       - /var/run/docker.sock:/var/run/docker.sock
 
@@ -61,5 +43,5 @@ services:
 
 volumes:
   minio_backup_data:
-  webdav_backup_data:
+    name: minio_backup_data
   app_data:

test/s3/run.sh

@@ -0,0 +1,63 @@
+#!/bin/sh
+
+set -e
+
+cd "$(dirname "$0")"
+. ../util.sh
+current_test=$(basename $(pwd))
+
+docker compose up -d --quiet-pull
+sleep 5
+
+docker compose exec backup backup
+
+sleep 5
+
+expect_running_containers "3"
+
+docker run --rm \
+  -v minio_backup_data:/minio_data \
+  alpine \
+  ash -c 'tar -xvf /minio_data/backup/test-hostnametoken.tar.gz -C /tmp && test -f /tmp/backup/app_data/offen.db'
+
+pass "Found relevant files in untared remote backups."
+
+# The second part of this test checks if backups get deleted when the retention
+# is set to 0 days (which it should not as it would mean all backups get deleted)
+BACKUP_RETENTION_DAYS="0" docker compose up -d
+sleep 5
+
+docker compose exec backup backup
+
+docker run --rm \
+  -v minio_backup_data:/minio_data \
+  alpine \
+  ash -c '[ $(find /minio_data/backup/ -type f | wc -l) = "1" ]'
+
+pass "Remote backups have not been deleted."
+
+# The third part of this test checks if old backups get deleted when the retention
+# is set to 7 days (which it should)
+
+BACKUP_RETENTION_DAYS="7" docker compose up -d
+sleep 5
+
+info "Create first backup with no prune"
+docker compose exec backup backup
+
+docker run --rm \
+  -v minio_backup_data:/minio_data \
+  alpine \
+  ash -c 'touch -d@$(( $(date +%s) - 1209600 )) /minio_data/backup/test-hostnametoken-old.tar.gz'
+
+info "Create second backup and prune"
+docker compose exec backup backup
+
+docker run --rm \
+  -v minio_backup_data:/minio_data \
+  alpine \
+  ash -c 'test ! -f /minio_data/backup/test-hostnametoken-old.tar.gz && test -f /minio_data/backup/test-hostnametoken.tar.gz'
+
+pass "Old remote backup has been pruned, new one is still present."
+
+docker compose down --volumes

test/secrets/docker-compose.yml

@@ -0,0 +1,78 @@
+# Copyright 2020-2021 - Offen Authors <hioffen@posteo.de>
+# SPDX-License-Identifier: Unlicense
+
+version: '3.8'
+
+services:
+  minio:
+    image: minio/minio:RELEASE.2020-08-04T23-10-51Z
+    deploy:
+      restart_policy:
+        condition: on-failure
+    environment:
+      MINIO_ROOT_USER: test
+      MINIO_ROOT_PASSWORD: test
+      MINIO_ACCESS_KEY: test
+      MINIO_SECRET_KEY: GMusLtUmILge2by+z890kQ
+    entrypoint: /bin/ash -c 'mkdir -p /data/backup && minio server /data'
+    volumes:
+      - backup_data:/data
+
+  backup:
+    image: offen/docker-volume-backup:${TEST_VERSION:-canary}
+    depends_on:
+      - minio
+    deploy:
+      restart_policy:
+        condition: on-failure
+    environment:
+      AWS_ACCESS_KEY_ID_FILE: /run/secrets/minio_root_user
+      AWS_SECRET_ACCESS_KEY_FILE: /run/secrets/minio_root_password
+      AWS_ENDPOINT: minio:9000
+      AWS_ENDPOINT_PROTO: http
+      AWS_S3_BUCKET_NAME: backup
+      BACKUP_FILENAME: test.tar.gz
+      BACKUP_CRON_EXPRESSION: 0 0 5 31 2 ?
+      BACKUP_RETENTION_DAYS: 7
+      BACKUP_PRUNING_LEEWAY: 5s
+    volumes:
+      - pg_data:/backup/pg_data:ro
+      - /var/run/docker.sock:/var/run/docker.sock
+    secrets:
+      - minio_root_user
+      - minio_root_password
+
+  offen:
+    image: offen/offen:latest
+    labels:
+      - docker-volume-backup.stop-during-backup=true
+    healthcheck:
+      disable: true
+    deploy:
+      replicas: 2
+      restart_policy:
+        condition: on-failure
+
+  pg:
+    image: postgres:14-alpine
+    environment:
+      POSTGRES_PASSWORD: example
+    labels:
+      - docker-volume-backup.stop-during-backup=true
+    volumes:
+      - pg_data:/var/lib/postgresql/data
+    deploy:
+      restart_policy:
+        condition: on-failure
+
+volumes:
+  backup_data:
+    name: backup_data
+  pg_data:
+    name: pg_data
+
+secrets:
+  minio_root_user:
+    external: true
+  minio_root_password:
+    external: true

test/secrets/run.sh

@@ -0,0 +1,44 @@
+#!/bin/sh
+
+set -e
+
+cd $(dirname $0)
+. ../util.sh
+current_test=$(basename $(pwd))
+
+docker swarm init
+
+printf "test" | docker secret create minio_root_user -
+printf "GMusLtUmILge2by+z890kQ" | docker secret create minio_root_password -
+
+docker stack deploy --compose-file=docker-compose.yml test_stack
+
+while [ -z $(docker ps -q -f name=backup) ]; do
+  info "Backup container not ready yet. Retrying."
+  sleep 1
+done
+
+sleep 20
+
+docker exec $(docker ps -q -f name=backup) backup
+
+docker run --rm \
+  -v backup_data:/data alpine \
+  ash -c 'tar -xf /data/backup/test.tar.gz && test -f /backup/pg_data/PG_VERSION'
+
+pass "Found relevant files in untared backup."
+
+sleep 5
+expect_running_containers "5"
+
+docker stack rm test_stack
+
+docker secret rm minio_root_password
+docker secret rm minio_root_user
+
+docker swarm leave --force
+
+sleep 10
+
+docker volume rm backup_data
+docker volume rm pg_data

test/ssh/docker-compose.yml

@@ -0,0 +1,47 @@
+version: '3'
+
+services:
+  ssh:
+    image: linuxserver/openssh-server:version-8.6_p1-r3
+    environment:
+      - PUID=1000
+      - PGID=1000
+      - USER_NAME=test
+    volumes:
+      - ./id_rsa.pub:/config/.ssh/authorized_keys
+      - ssh_backup_data:/tmp
+
+  backup:
+    image: offen/docker-volume-backup:${TEST_VERSION:-canary}
+    hostname: hostnametoken
+    depends_on:
+      - ssh
+    restart: always
+    environment:
+      BACKUP_FILENAME_EXPAND: 'true'
+      BACKUP_FILENAME: test-$$HOSTNAME.tar.gz
+      BACKUP_CRON_EXPRESSION: 0 0 5 31 2 ?
+      BACKUP_RETENTION_DAYS: ${BACKUP_RETENTION_DAYS:-7}
+      BACKUP_PRUNING_LEEWAY: 5s
+      BACKUP_PRUNING_PREFIX: test
+      SSH_HOST_NAME: ssh
+      SSH_PORT: 2222
+      SSH_USER: test
+      SSH_REMOTE_PATH: /tmp
+      SSH_IDENTITY_PASSPHRASE: test1234
+    volumes:
+      - ./id_rsa:/root/.ssh/id_rsa
+      - app_data:/backup/app_data:ro
+      - /var/run/docker.sock:/var/run/docker.sock
+
+  offen:
+    image: offen/offen:latest
+    labels:
+      - docker-volume-backup.stop-during-backup=true
+    volumes:
+      - app_data:/var/opt/offen
+
+volumes:
+  ssh_backup_data:
+    name: ssh_backup_data
+  app_data:

test/ssh/run.sh

@@ -0,0 +1,68 @@
+#!/bin/sh
+
+set -e
+
+cd "$(dirname "$0")"
+. ../util.sh
+current_test=$(basename $(pwd))
+
+ssh-keygen -t rsa -m pem -b 4096 -N "test1234" -f id_rsa -C "docker-volume-backup@local"
+
+docker compose up -d --quiet-pull
+sleep 5
+
+docker compose exec backup backup
+
+sleep 5
+
+expect_running_containers 3
+
+docker run --rm \
+  -v ssh_backup_data:/ssh_data \
+  alpine \
+  ash -c 'tar -xvf /ssh_data/test-hostnametoken.tar.gz -C /tmp && test -f /tmp/backup/app_data/offen.db'
+
+pass "Found relevant files in decrypted and untared remote backups."
+
+# The second part of this test checks if backups get deleted when the retention
+# is set to 0 days (which it should not as it would mean all backups get deleted)
+BACKUP_RETENTION_DAYS="0" docker compose up -d
+sleep 5
+
+docker compose exec backup backup
+
+docker run --rm \
+  -v ssh_backup_data:/ssh_data \
+  alpine \
+  ash -c '[ $(find /ssh_data/ -type f | wc -l) = "1" ]'
+
+pass "Remote backups have not been deleted."
+
+# The third part of this test checks if old backups get deleted when the retention
+# is set to 7 days (which it should)
+
+BACKUP_RETENTION_DAYS="7" docker compose up -d
+sleep 5
+
+info "Create first backup with no prune"
+docker compose exec backup backup
+
+# Set the modification date of the old backup to 14 days ago
+docker run --rm \
+  -v ssh_backup_data:/ssh_data \
+  --user 1000 \
+  alpine \
+  ash -c 'touch -d@$(( $(date +%s) - 1209600 )) /ssh_data/test-hostnametoken-old.tar.gz'
+
+info "Create second backup and prune"
+docker compose exec backup backup
+
+docker run --rm \
+  -v ssh_backup_data:/ssh_data \
+  alpine \
+  ash -c 'test ! -f /ssh_data/test-hostnametoken-old.tar.gz && test -f /ssh_data/test-hostnametoken.tar.gz'
+
+pass "Old remote backup has been pruned, new one is still present."
+
+docker compose down --volumes
+rm -f id_rsa id_rsa.pub

test/swarm/docker-compose.yml

@@ -64,4 +64,6 @@ services:
 
 volumes:
   backup_data:
+    name: backup_data
   pg_data:
+    name: pg_data

test/swarm/run.sh

@@ -3,13 +3,15 @@
 set -e
 
 cd $(dirname $0)
+. ../util.sh
+current_test=$(basename $(pwd))
 
 docker swarm init
 
 docker stack deploy --compose-file=docker-compose.yml test_stack
 
 while [ -z $(docker ps -q -f name=backup) ]; do
-  echo "[TEST:INFO] Backup container not ready yet. Retrying."
+  info "Backup container not ready yet. Retrying."
   sleep 1
 done
 
@@ -17,19 +19,19 @@ sleep 20
 
 docker exec $(docker ps -q -f name=backup) backup
 
-docker run --rm -it \
+docker run --rm \
-  -v test_stack_backup_data:/data alpine \
+  -v backup_data:/data alpine \
   ash -c 'tar -xf /data/backup/test.tar.gz && test -f /backup/pg_data/PG_VERSION'
 
-echo "[TEST:PASS] Found relevant files in untared backup."
+pass "Found relevant files in untared backup."
 
 sleep 5
-if [ "$(docker ps -q | wc -l)" != "5" ]; then
+expect_running_containers "5"
-  echo "[TEST:FAIL] Expected all containers to be running post backup, instead seen:"
-  docker ps -a
-  exit 1
-fi
-echo "[TEST:PASS] All containers running post backup."
 
 docker stack rm test_stack
 docker swarm leave --force
+
+sleep 10
+
+docker volume rm backup_data
+docker volume rm pg_data

test/user/.gitignore

@@ -0,0 +1,2 @@
+local
+backup

test/user/docker-compose.yml

@@ -0,0 +1,30 @@
+version: '2.4'
+
+services:
+  alpine:
+    image: alpine:3.17.3
+    tty: true 
+    volumes:
+      - app_data:/tmp
+    labels:
+      - docker-volume-backup.archive-pre.user=testuser
+      - docker-volume-backup.archive-pre=/bin/sh -c 'whoami > /tmp/whoami.txt'
+
+
+  backup:
+    image: offen/docker-volume-backup:${TEST_VERSION:-canary}
+    deploy:
+      restart_policy:
+        condition: on-failure
+    environment:
+      BACKUP_FILENAME: test.tar.gz
+      BACKUP_CRON_EXPRESSION: 0 0 5 31 2 ?
+      EXEC_FORWARD_OUTPUT: "true"
+    volumes:
+      - ./local:/archive
+      - app_data:/backup/data:ro
+      - /var/run/docker.sock:/var/run/docker.sock
+
+volumes:
+  app_data:
+  archive:

test/user/run.sh

@@ -0,0 +1,30 @@
+#!/bin/sh
+
+set -e
+
+cd $(dirname $0)
+. ../util.sh
+current_test=$(basename $(pwd))
+
+docker compose up -d --quiet-pull
+
+user_name=testuser
+docker exec user-alpine-1 adduser --disabled-password "$user_name"
+
+docker compose exec backup backup
+
+tar -xvf ./local/test.tar.gz
+if [ ! -f ./backup/data/whoami.txt ]; then
+  fail "Could not find file written by pre command."
+fi
+pass "Found expected file."
+
+tar -xvf ./local/test.tar.gz
+if [ "$(cat ./backup/data/whoami.txt)" != "$user_name" ]; then
+  fail "Could not find expected user name."
+fi
+pass "Found expected user."
+
+docker compose down --volumes
+sudo rm -rf ./local
+

test/util.sh

@@ -0,0 +1,23 @@
+#!/bin/sh
+
+set -e
+
+info () {
+  echo "[test:${current_test:-none}:info] "$1""
+}
+
+pass () {
+  echo "[test:${current_test:-none}:pass] "$1""
+}
+
+fail () {
+  echo "[test:${current_test:-none}:fail] "$1""
+  exit 1
+}
+
+expect_running_containers () {
+  if [ "$(docker ps -q | wc -l)" != "$1" ]; then
+    fail "Expected $1 containers to be running, instead seen: "$(docker ps -a | wc -l)""
+  fi
+  pass "$1 containers running."
+}

test/webdav/docker-compose.yml

@@ -0,0 +1,45 @@
+version: '3'
+
+services:
+  webdav:
+    image: bytemark/webdav:2.4
+    environment:
+      AUTH_TYPE: Digest
+      USERNAME: test
+      PASSWORD: test
+    volumes:
+      - webdav_backup_data:/var/lib/dav
+
+  backup:
+    image: offen/docker-volume-backup:${TEST_VERSION:-canary}
+    hostname: hostnametoken
+    depends_on:
+      - webdav
+    restart: always
+    environment:
+      BACKUP_FILENAME_EXPAND: 'true'
+      BACKUP_FILENAME: test-$$HOSTNAME.tar.gz
+      BACKUP_CRON_EXPRESSION: 0 0 5 31 2 ?
+      BACKUP_RETENTION_DAYS: ${BACKUP_RETENTION_DAYS:-7}
+      BACKUP_PRUNING_LEEWAY: 5s
+      BACKUP_PRUNING_PREFIX: test
+      WEBDAV_URL: http://webdav/
+      WEBDAV_URL_INSECURE: 'true'
+      WEBDAV_PATH: /my/new/path/
+      WEBDAV_USERNAME: test
+      WEBDAV_PASSWORD: test
+    volumes:
+      - app_data:/backup/app_data:ro
+      - /var/run/docker.sock:/var/run/docker.sock
+
+  offen:
+    image: offen/offen:latest
+    labels:
+      - docker-volume-backup.stop-during-backup=true
+    volumes:
+      - app_data:/var/opt/offen
+
+volumes:
+  webdav_backup_data:
+    name: webdav_backup_data
+  app_data:

test/webdav/run.sh

@@ -0,0 +1,65 @@
+#!/bin/sh
+
+set -e
+
+cd "$(dirname "$0")"
+. ../util.sh
+current_test=$(basename $(pwd))
+
+docker compose up -d --quiet-pull
+sleep 5
+
+docker compose exec backup backup
+
+sleep 5
+
+expect_running_containers "3"
+
+docker run --rm \
+  -v webdav_backup_data:/webdav_data \
+  alpine \
+  ash -c 'tar -xvf /webdav_data/data/my/new/path/test-hostnametoken.tar.gz -C /tmp && test -f /tmp/backup/app_data/offen.db'
+
+pass "Found relevant files in untared remote backup."
+
+# The second part of this test checks if backups get deleted when the retention
+# is set to 0 days (which it should not as it would mean all backups get deleted)
+BACKUP_RETENTION_DAYS="0" docker compose up -d
+sleep 5
+
+docker compose exec backup backup
+
+docker run --rm \
+  -v webdav_backup_data:/webdav_data \
+  alpine \
+  ash -c '[ $(find /webdav_data/data/my/new/path/ -type f | wc -l) = "1" ]'
+
+pass "Remote backups have not been deleted."
+
+# The third part of this test checks if old backups get deleted when the retention
+# is set to 7 days (which it should)
+
+BACKUP_RETENTION_DAYS="7" docker compose up -d
+sleep 5
+
+info "Create first backup with no prune"
+docker compose exec backup backup
+
+# Set the modification date of the old backup to 14 days ago
+docker run --rm \
+  -v webdav_backup_data:/webdav_data \
+  --user 82 \
+  alpine \
+  ash -c 'touch -d@$(( $(date +%s) - 1209600 )) /webdav_data/data/my/new/path/test-hostnametoken-old.tar.gz'
+
+info "Create second backup and prune"
+docker compose exec backup backup
+
+docker run --rm \
+  -v webdav_backup_data:/webdav_data \
+  alpine \
+  ash -c 'test ! -f /webdav_data/data/my/new/path/test-hostnametoken-old.tar.gz && test -f /webdav_data/data/my/new/path/test-hostnametoken.tar.gz'
+
+pass "Old remote backup has been pruned, new one is still present."
+
+docker compose down --volumes

test/zstd/run.sh

@@ -0,0 +1,46 @@
+#!/bin/sh
+
+set -e
+
+cd $(dirname $0)
+. ../util.sh
+current_test=$(basename $(pwd))
+
+docker network create test_network
+docker volume create app_data
+
+mkdir -p local
+
+docker run -d -q \
+  --name offen \
+  --network test_network \
+  -v app_data:/var/opt/offen/ \
+  offen/offen:latest
+
+sleep 10
+
+docker run --rm -q \
+  --network test_network \
+  -v app_data:/backup/app_data \
+  -v ./local:/archive \
+  -v /var/run/docker.sock:/var/run/docker.sock \
+  --env BACKUP_COMPRESSION=zst \
+  --env BACKUP_FILENAME='test.{{ .Extension }}' \
+  --entrypoint backup \
+  offen/docker-volume-backup:${TEST_VERSION:-canary}
+
+tmp_dir=$(mktemp -d)
+tar -xvf ./local/test.tar.zst --zstd -C $tmp_dir
+if [ ! -f "$tmp_dir/backup/app_data/offen.db" ]; then
+  fail "Could not find expected file in untared archive."
+fi
+pass "Found relevant files in untared local backup."
+
+# This test does not stop containers during backup. This is happening on
+# purpose in order to cover this setup as well.
+expect_running_containers "1"
+
+docker rm $(docker stop offen)
+
+docker volume rm app_data
+docker network rm test_network