Add support for Azure Blob Storage (#171)

* Scaffold Azure storage backend that does nothing yet

* Implement copy for Azure Blob Storage

* Set up automated testing for Azure Storage

* Implement pruning for Azure blob storage

* Add documentation for Azure Blob Storage

* Add support for remote path

* Add azure to notifications doc

* Tidy go.mod file

* Allow use of managed identity credential

* Use volume in tests

* Auto append trailing slash to endpoint if needed, clarify docs, tidy mod file

.circleci/config.yml

@@ -5,6 +5,7 @@ jobs:
     machine:
       image: ubuntu-2004:202201-02
     working_directory: ~/docker-volume-backup
+    resource_class: large
     steps:
       - checkout
       - run:
@@ -29,11 +30,13 @@ jobs:
           DOCKER_BUILDKIT: '1'
           DOCKER_CLI_EXPERIMENTAL: enabled
     working_directory: ~/docker-volume-backup
+    resource_class: large
     steps:
       - checkout
       - setup_remote_docker:
           version: 20.10.6
-      - docker/install-docker-credential-helper
+      - docker/install-docker-credential-helper:
+          release-tag: v0.6.4
       - docker/configure-docker-credentials-store
       - run:
           name: Push to Docker Hub
@@ -69,4 +72,4 @@ workflows:
               only: /^v.*/
 
 orbs:
-  docker: circleci/docker@1.0.1
+  docker: circleci/docker@2.1.4

.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 +1,28 @@
+---
+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.
+
+**Desktop (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 +1,20 @@
+---
+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 +1,20 @@
+---
+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.

Dockerfile

@@ -1,16 +1,15 @@
 # Copyright 2021 - Offen Authors <hioffen@posteo.de>
 # SPDX-License-Identifier: MPL-2.0
 
-FROM golang:1.18-alpine as builder
+FROM golang:1.19-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:3.17
 
 WORKDIR /root
 

README.md

@@ -4,10 +4,10 @@
 
 # docker-volume-backup
 
-Backup Docker volumes locally or to any S3 compatible storage.
+Backup Docker volumes locally or to any S3, WebDAV 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 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 -->
 
@@ -20,7 +20,7 @@ It handles __recurring or one-off backups of Docker volumes__ to a __local direc
   - [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 +28,20 @@ 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)
   - [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)
 - [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 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)
@@ -193,6 +199,14 @@ 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 +234,18 @@ 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"
+
 # You can also backup files to any WebDAV server:
 
 # The URL of the remote WebDAV server
@@ -245,6 +271,59 @@ 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/"
+
 # 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 +389,7 @@ 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
@@ -395,7 +474,7 @@ You can populate below template according to your requirements and use it as you
 # EMAIL_SMTP_PORT="<port>"
 ```
 
-In case you encouter double quoted values in your configuration you might be running an [older version of `docker-compose`].
+In case you encouter double quoted values in your configuration you might be running an [older version of `docker-compose`][compose-issue].
 You can work around this by either updating `docker-compose` or unquoting your configuration values.
 
 [compose-issue]: https://github.com/docker/compose/issues/2854
@@ -502,11 +581,16 @@ 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 +604,7 @@ 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 +624,7 @@ 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:
@@ -556,7 +640,7 @@ 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.
 
 ### Encrypting your backup using GPG
@@ -682,7 +766,7 @@ 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'
@@ -694,8 +778,8 @@ 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
@@ -710,6 +794,23 @@ 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.
@@ -746,6 +847,25 @@ 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.
@@ -779,6 +899,60 @@ 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`.
+
 ## Recipes
 
 This section lists configuration for some real-world use cases that you can mix and match according to your needs.
@@ -848,6 +1022,38 @@ 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 +1076,50 @@ 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 locally
 
 ```yml
@@ -991,9 +1241,9 @@ 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

@@ -63,7 +63,7 @@ func compress(paths []string, outFilePath, subPath string) error {
 
 	for _, p := range paths {
 		if err := writeTarGz(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)
 		}
 	}
 

cmd/backup/config.go

@@ -4,7 +4,11 @@
 package main
 
 import (
+	"crypto/x509"
+	"encoding/pem"
 	"fmt"
+	"io/ioutil"
+	"os"
 	"regexp"
 	"time"
 )
@@ -12,42 +16,90 @@ import (
 // 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"`
+	BackupSources                 string        `split_words:"true" default:"/backup"`
-	AwsEndpoint                string        `split_words:"true" default:"s3.amazonaws.com"`
+	BackupFilename                string        `split_words:"true" default:"backup-%Y-%m-%dT%H-%M-%S.tar.gz"`
-	AwsEndpointProto           string        `split_words:"true" default:"https"`
+	BackupFilenameExpand          bool          `split_words:"true"`
-	AwsEndpointInsecure        bool          `split_words:"true"`
+	BackupLatestSymlink           string        `split_words:"true"`
-	AwsAccessKeyID             string        `envconfig:"AWS_ACCESS_KEY_ID"`
+	BackupArchive                 string        `split_words:"true" default:"/archive"`
-	AwsSecretAccessKey         string        `split_words:"true"`
+	BackupRetentionDays           int32         `split_words:"true" default:"-1"`
-	AwsIamRoleEndpoint         string        `split_words:"true"`
+	BackupPruningLeeway           time.Duration `split_words:"true" default:"1m"`
-	GpgPassphrase              string        `split_words:"true"`
+	BackupPruningPrefix           string        `split_words:"true"`
-	NotificationURLs           []string      `envconfig:"NOTIFICATION_URLS"`
+	BackupStopContainerLabel      string        `split_words:"true" default:"true"`
-	NotificationLevel          string        `split_words:"true" default:"error"`
+	BackupFromSnapshot            bool          `split_words:"true"`
-	EmailNotificationRecipient string        `split_words:"true"`
+	BackupExcludeRegexp           RegexpDecoder `split_words:"true"`
-	EmailNotificationSender    string        `split_words:"true" default:"noreply@nohost"`
+	GpgPassphrase                 string        `split_words:"true"`
-	EmailSMTPHost              string        `envconfig:"EMAIL_SMTP_HOST"`
+	NotificationURLs              []string      `envconfig:"NOTIFICATION_URLS"`
-	EmailSMTPPort              int           `envconfig:"EMAIL_SMTP_PORT" default:"587"`
+	NotificationLevel             string        `split_words:"true" default:"error"`
-	EmailSMTPUsername          string        `envconfig:"EMAIL_SMTP_USERNAME"`
+	EmailNotificationRecipient    string        `split_words:"true"`
-	EmailSMTPPassword          string        `envconfig:"EMAIL_SMTP_PASSWORD"`
+	EmailNotificationSender       string        `split_words:"true" default:"noreply@nohost"`
-	WebdavUrl                  string        `split_words:"true"`
+	EmailSMTPHost                 string        `envconfig:"EMAIL_SMTP_HOST"`
-	WebdavUrlInsecure          bool          `split_words:"true"`
+	EmailSMTPPort                 int           `envconfig:"EMAIL_SMTP_PORT" default:"587"`
-	WebdavPath                 string        `split_words:"true" default:"/"`
+	EmailSMTPUsername             string        `envconfig:"EMAIL_SMTP_USERNAME"`
-	WebdavUsername             string        `split_words:"true"`
+	EmailSMTPPassword             string        `envconfig:"EMAIL_SMTP_PASSWORD"`
-	WebdavPassword             string        `split_words:"true"`
+	WebdavUrl                     string        `split_words:"true"`
-	ExecLabel                  string        `split_words:"true"`
+	WebdavUrlInsecure             bool          `split_words:"true"`
-	ExecForwardOutput          bool          `split_words:"true"`
+	WebdavPath                    string        `split_words:"true" default:"/"`
-	LockTimeout                time.Duration `split_words:"true" default:"60m"`
+	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/"`
+}
+
+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 CertDecoder struct {
+	Cert *x509.Certificate
+}
+
+func (c *CertDecoder) Decode(v string) error {
+	if v == "" {
+		return nil
+	}
+	content, err := ioutil.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 {

cmd/backup/exec.go

@@ -23,10 +23,14 @@ import (
 
 func (s *script) exec(containerRef string, command 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,
 	})
 	if err != nil {
 		return nil, nil, fmt.Errorf("exec: error creating container exec: %w", err)
@@ -93,16 +97,68 @@ func (s *script) runLabeledCommands(label string) error {
 		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{
+			Quiet:   true,
+			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{
+			Quiet:   true,
+			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]
+			if !ok && label == "docker-volume-backup.archive-pre" {
+				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"]
+			}
+
 			s.logger.Infof("Running %s command %s for container %s", label, cmd, strings.TrimPrefix(c.Names[0], "/"))
 			stdout, stderr, err := s.exec(c.ID, cmd)
 			if s.c.ExecForwardOutput {
@@ -121,3 +177,27 @@ 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

@@ -6,6 +6,8 @@ package main
 import (
 	"fmt"
 	"sort"
+
+	"github.com/offen/docker-volume-backup/internal/utilities"
 )
 
 // hook contains a queued action that can be trigger them when the script
@@ -50,7 +52,7 @@ func (s *script) runHooks(err error) error {
 		}
 	}
 	if len(actionErrors) != 0 {
-		return join(actionErrors...)
+		return utilities.Join(actionErrors...)
 	}
 	return nil
 }

cmd/backup/lock.go

@@ -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 {

cmd/backup/main.go

@@ -38,14 +38,7 @@ func main() {
 		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 +49,10 @@ 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

@@ -7,10 +7,12 @@ import (
 	"bytes"
 	_ "embed"
 	"fmt"
+	"os"
 	"text/template"
 	"time"
 
 	sTypes "github.com/containrrr/shoutrrr/pkg/types"
+	"github.com/offen/docker-volume-backup/internal/utilities"
 )
 
 //go:embed notifications.tmpl
@@ -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", utilities.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

@@ -5,18 +5,23 @@ package main
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"io"
 	"io/fs"
-	"net/http"
 	"os"
 	"path"
 	"path/filepath"
-	"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/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/offen/docker-volume-backup/internal/utilities"
+
 	"github.com/containrrr/shoutrrr"
 	"github.com/containrrr/shoutrrr/pkg/router"
 	"github.com/docker/docker/api/types"
@@ -25,25 +30,22 @@ import (
 	"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"
-	"github.com/studio-b12/gowebdav"
 	"golang.org/x/crypto/openpgp"
+	"golang.org/x/sync/errgroup"
 )
 
 // 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    *logrus.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
@@ -70,7 +72,13 @@ func newScript() (*script, error) {
 		stats: &Stats{
 			StartTime: time.Now(),
 			LogOutput: logBuffer,
-			Storages:  StoragesStats{},
+			Storages: map[string]StorageStats{
+				"S3":     {},
+				"WebDAV": {},
+				"SSH":    {},
+				"Local":  {},
+				"Azure":  {},
+			},
 		},
 	}
 
@@ -102,61 +110,100 @@ func newScript() (*script, error) {
 		s.cli = cli
 	}
 
+	logFunc := func(logType storage.LogLevel, context string, msg string, params ...interface{}) {
+		switch logType {
+		case storage.LogLevelWarning:
+			s.logger.Warnf("["+context+"] "+msg, params...)
+		case storage.LogLevelError:
+			s.logger.Errorf("["+context+"] "+msg, params...)
+		case storage.LogLevelInfo:
+		default:
+			s.logger.Infof("["+context+"] "+msg, params...)
+		}
+	}
+
 	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,
+		}
+		if s3Backend, err := s3.NewStorageBackend(s3Config, logFunc); err != nil {
+			return nil, 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, 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, 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, err
+		}
+		s.storages = append(s.storages, azureBackend)
 	}
 
 	if s.c.EmailNotificationRecipient != "" {
@@ -225,22 +272,6 @@ 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.
@@ -253,7 +284,7 @@ func (s *script) stopContainers() (func() error, error) {
 		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(
@@ -269,7 +300,7 @@ 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 {
@@ -296,9 +327,9 @@ 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...),
+			utilities.Join(stopErrors...),
 		)
 	}
 
@@ -333,7 +364,7 @@ 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
 				if _, err := s.cli.ServiceUpdate(
@@ -347,9 +378,9 @@ 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...),
+				utilities.Join(restartErrors...),
 			)
 		}
 		s.logger.Infof(
@@ -360,9 +391,9 @@ func (s *script) stopContainers() (func() error, error) {
 	}, 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 {
@@ -370,13 +401,13 @@ 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)
 			return nil
@@ -385,7 +416,7 @@ func (s *script) takeBackup() error {
 			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)
 	}
@@ -393,7 +424,7 @@ func (s *script) takeBackup() error {
 	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)
 		return nil
@@ -401,7 +432,7 @@ func (s *script) takeBackup() error {
 
 	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 +447,21 @@ 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 {
-		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)
 	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
 	}
@@ -438,35 +469,35 @@ 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)
 		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
@@ -474,12 +505,12 @@ func (s *script) encryptBackup() error {
 	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 +520,17 @@ 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 +544,28 @@ 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 {
+			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
 }
 

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

@@ -1,25 +1,31 @@
 module github.com/offen/docker-volume-backup
 
-go 1.18
+go 1.19
 
 require (
+	github.com/Azure/azure-sdk-for-go/sdk/azidentity v1.2.0
+	github.com/Azure/azure-sdk-for-go/sdk/storage/azblob v0.6.1
 	github.com/containrrr/shoutrrr v0.5.2
 	github.com/cosiner/argv v0.1.0
 	github.com/docker/docker v20.10.11+incompatible
 	github.com/gofrs/flock v0.8.1
 	github.com/kelseyhightower/envconfig v1.4.0
 	github.com/leekchan/timeutil v0.0.0-20150802142658-28917288c48d
-	github.com/minio/minio-go/v7 v7.0.16
+	github.com/minio/minio-go/v7 v7.0.44
 	github.com/otiai10/copy v1.7.0
-	github.com/sirupsen/logrus v1.8.1
+	github.com/pkg/sftp v1.13.5
+	github.com/sirupsen/logrus v1.9.0
 	github.com/studio-b12/gowebdav v0.0.0-20220128162035-c7b1ff8a5e62
-	golang.org/x/crypto v0.0.0-20210817164053-32db794688a5
+	golang.org/x/crypto v0.3.0
-	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c
+	golang.org/x/sync v0.0.0-20220601150217-0de741cfad7f
 )
 
 require (
-	github.com/Microsoft/go-winio v0.4.17 // indirect
+	github.com/Azure/azure-sdk-for-go/sdk/azcore v1.1.4 // indirect
-	github.com/containerd/containerd v1.5.5 // indirect
+	github.com/Azure/azure-sdk-for-go/sdk/internal v1.0.1 // indirect
+	github.com/AzureAD/microsoft-authentication-library-for-go v0.7.0 // indirect
+	github.com/Microsoft/go-winio v0.5.2 // indirect
+	github.com/containerd/containerd v1.6.6 // indirect
 	github.com/docker/distribution v2.7.1+incompatible // indirect
 	github.com/docker/go-connections v0.4.0 // indirect
 	github.com/docker/go-units v0.4.0 // indirect
@@ -27,34 +33,42 @@ require (
 	github.com/fatih/color v1.10.0 // indirect
 	github.com/fsnotify/fsnotify v1.4.9 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
-	github.com/golang/protobuf v1.5.0 // indirect
+	github.com/golang-jwt/jwt/v4 v4.4.2 // indirect
+	github.com/golang/protobuf v1.5.2 // 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 v1.13.6 // indirect
+	github.com/klauspost/compress v1.15.12 // indirect
-	github.com/klauspost/cpuid/v2 v2.0.9 // indirect
+	github.com/klauspost/cpuid/v2 v2.2.1 // 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-isatty v0.0.12 // indirect
 	github.com/minio/md5-simd v1.1.2 // indirect
 	github.com/minio/sha256-simd v1.0.0 // 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 v1.0.1 // indirect
+	github.com/opencontainers/image-spec v1.0.3-0.20211202183452-c5a74bcca799 // indirect
+	github.com/pkg/browser v0.0.0-20210115035449-ce105d075bb4 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
-	github.com/rs/xid v1.3.0 // indirect
+	github.com/rs/xid v1.4.0 // indirect
-	golang.org/x/net v0.0.0-20210226172049-e18ecbb05110 // indirect
+	golang.org/x/net v0.2.0 // indirect
-	golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1 // indirect
+	golang.org/x/sys v0.2.0 // indirect
-	golang.org/x/text v0.3.6 // indirect
+	golang.org/x/text v0.4.0 // indirect
 	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
-	google.golang.org/genproto v0.0.0-20201110150050-8816d57aaa9a // indirect
+	google.golang.org/genproto v0.0.0-20220602131408-e326c6e8e9c8 // indirect
-	google.golang.org/grpc v1.33.2 // indirect
+	google.golang.org/grpc v1.47.0 // indirect
-	google.golang.org/protobuf v1.26.0 // indirect
+	google.golang.org/protobuf v1.28.0 // indirect
-	gopkg.in/ini.v1 v1.65.0 // indirect
+	gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f // indirect
+	gopkg.in/ini.v1 v1.67.0 // indirect
 	gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7 // 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"
+	"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"
+	"github.com/offen/docker-volume-backup/internal/utilities"
+)
+
+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), "Azure Blob Storage backup(s)", func() error {
+		wg := sync.WaitGroup{}
+		wg.Add(len(matches))
+		var errors []error
+
+		for _, match := range matches {
+			name := match
+			go func() {
+				_, err := b.client.DeleteBlob(context.Background(), b.containerName, name, nil)
+				if err != nil {
+					errors = append(errors, err)
+				}
+				wg.Done()
+			}()
+		}
+		wg.Wait()
+		if len(errors) != 0 {
+			return utilities.Join(errors...)
+		}
+		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 (
+	"fmt"
+	"io"
+	"os"
+	"path"
+	"path/filepath"
+	"time"
+
+	"github.com/offen/docker-volume-backup/internal/storage"
+	"github.com/offen/docker-volume-backup/internal/utilities"
+)
+
+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 local archive: %w", err)
+	}
+	b.Log(storage.LogLevelInfo, b.Name(), "Stored copy of backup `%s` in local archive `%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), "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(
+				"(*localStorage).Prune: %d error(s) deleting local files, starting with: %w",
+				len(removeErrors),
+				utilities.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 +1,170 @@
+// Copyright 2022 - Offen Authors <hioffen@posteo.de>
+// SPDX-License-Identifier: MPL-2.0
+
+package s3
+
+import (
+	"context"
+	"crypto/x509"
+	"errors"
+	"fmt"
+	"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"
+	"github.com/offen/docker-volume-backup/internal/utilities"
+)
+
+type s3Storage struct {
+	*storage.StorageBackend
+	client       *minio.Client
+	bucket       string
+	storageClass string
+}
+
+// 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
+	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,
+	}, 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)
+
+	if _, err := b.client.FPutObject(context.Background(), b.bucket, filepath.Join(b.DestinationPath, name), file, minio.PutObjectOptions{
+		ContentType:  "application/tar+gzip",
+		StorageClass: b.storageClass,
+	}); 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, "remote backup(s)", 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 utilities.Join(removeErrors...)
+		}
+		return nil
+	}); err != nil {
+		return stats, err
+	}
+
+	return stats, nil
+}

internal/storage/ssh/ssh.go

@@ -0,0 +1,190 @@
+// Copyright 2022 - Offen Authors <hioffen@posteo.de>
+// SPDX-License-Identifier: MPL-2.0
+
+package ssh
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"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 := ioutil.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 on SSH storage: %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 to SSH storage: %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 to SSH storage: %w", err)
+		}
+
+		tot, err := destination.Write(chunk[:num])
+		if err != nil {
+			return fmt.Errorf("(*sshStorage).Copy: Error uploading the file to SSH storage: %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 SSH storage '%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 from SSH storage: %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), "SSH backup(s)", 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 from SSH storage: %w", err)
+			}
+		}
+		return nil
+	}); err != nil {
+		return stats, err
+	}
+
+	return stats, nil
+}

internal/storage/storage.go

@@ -0,0 +1,61 @@
+// 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 ...interface{})
+
+// 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, description string, 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 %s as their age exceeded the configured retention period of %d days.",
+			lenMatches,
+			lenCandidates,
+			description,
+			b.RetentionDays,
+		)
+	} else if lenMatches != 0 && lenMatches == lenCandidates {
+		b.Log(LogLevelWarning, context, "The current configuration would delete all %d existing %s.", lenMatches, description)
+		b.Log(LogLevelWarning, context, "Refusing to do so, please check your configuration.")
+	} else {
+		b.Log(LogLevelInfo, context, "None of %d existing %s were pruned.", lenCandidates, description)
+	}
+	return nil
+}

internal/storage/webdav/webdav.go

@@ -0,0 +1,121 @@
+// 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 {
+	bytes, err := os.ReadFile(file)
+	_, name := path.Split(file)
+	if err != nil {
+		return fmt.Errorf("(*webDavStorage).Copy: Error reading the file to be uploaded: %w", err)
+	}
+	if err := b.client.MkdirAll(b.DestinationPath, 0644); err != nil {
+		return fmt.Errorf("(*webDavStorage).Copy: Error creating directory '%s' on WebDAV server: %w", b.DestinationPath, err)
+	}
+	if err := b.client.Write(filepath.Join(b.DestinationPath, name), bytes, 0644); err != nil {
+		return fmt.Errorf("(*webDavStorage).Copy: Error uploading the file to WebDAV server: %w", err)
+	}
+	b.Log(storage.LogLevelInfo, b.Name(), "Uploaded a copy of backup '%s' to WebDAV URL '%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, "WebDAV backup(s)", 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 from WebDAV storage: %w", err)
+			}
+		}
+		return nil
+	}); err != nil {
+		return stats, err
+	}
+
+	return stats, nil
+}

internal/utilities/util.go

@@ -0,0 +1,24 @@
+// Copyright 2022 - Offen Authors <hioffen@posteo.de>
+// SPDX-License-Identifier: MPL-2.0
+
+package utilities
+
+import (
+	"errors"
+	"strings"
+)
+
+// 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, ", ") + "]")
+}

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 +1,40 @@
+#!/bin/sh
+
+set -e
+
+cd "$(dirname "$0")"
+. ../util.sh
+current_test=$(basename $(pwd))
+
+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 backup backup
+
+sleep 5
+
+expect_running_containers "3"
+
+docker-compose run --rm az_cli \
+  az storage blob download -f /dump/test.tar.gz -c test-container -n path/to/backup/test.tar.gz
+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)
+# 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-compose run --rm az_cli \
+  az storage blob download -f /dump/test.tar.gz -c test-container -n path/to/backup/test.tar.gz
+test -f ./local/test.tar.gz
+
+pass "Remote backups have not been deleted."
+
+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
+sleep 5
+
+docker compose exec backup backup
+
+sleep 5
+
+expect_running_containers "3"
+
+docker run --rm -it \
+  -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
@@ -50,17 +52,11 @@ docker run --rm -it \
   -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:

test/commands/run.sh

@@ -3,39 +3,43 @@
 set -e
 
 cd $(dirname $0)
+. ../util.sh
+current_test=$(basename $(pwd))
 
-
+docker compose up -d
-docker-compose up -d
 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."
 
 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
 
@@ -47,16 +51,14 @@ sudo cp -r $(docker volume inspect --format='{{ .Mountpoint }}' test_stack_archi
 
 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
 
 # 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/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 +1,28 @@
+#!/bin/sh
+
+set -e
+
+cd "$(dirname "$0")"
+. ../util.sh
+current_test=$(basename $(pwd))
+
+mkdir -p local
+
+export TEST_VERSION="${TEST_VERSION:-canary}-with-rsync"
+
+docker build . -t offen/docker-volume-backup:$TEST_VERSION
+
+docker compose up -d
+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 $(pwd))
+
+mkdir -p local
+
+docker compose up -d
+sleep 5
+
+docker compose exec backup backup
+
+expect_running_containers "2"
+
+tmp_dir=$(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
 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 +1,55 @@
+#!/bin/sh
+
+set -e
+
+cd "$(dirname "$0")"
+. ../util.sh
+current_test=$(basename $(pwd))
+
+mkdir -p local
+
+docker compose up -d
+sleep 5
+
+# A symlink for a known file in the volume is created so the test can check
+# whether symlinks are preserved on backup.
+docker compose exec offen ln -s /var/opt/offen/offen.db /var/opt/offen/db.link
+docker compose exec backup backup
+
+sleep 5
+
+expect_running_containers "2"
+
+tmp_dir=$(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 "$tmp_dir/backup/app_data/db.link" ]; then
+  fail "Could not find expected symlink in untared archive."
+fi
+
+pass "Found relevant files in decrypted and untared local backup."
+
+if [ ! -L ./local/test-hostnametoken.latest.tar.gz.gpg ]; then
+  fail "Could not find symlink to latest version."
+fi
+
+pass "Found symlink to latest version in local backup."
+
+# The second part of this test checks if backups get deleted when the retention
+# is set to 0 days (which it should not as it would mean all backups get deleted)
+# TODO: find out if we can test actual deletion without having to wait for a day
+BACKUP_RETENTION_DAYS="0" docker compose up -d
+sleep 5
+
+docker compose exec backup backup
+
+if [ "$(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."
+
+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
 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
 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/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 +1,42 @@
+#!/bin/sh
+
+set -e
+
+cd "$(dirname "$0")"
+. ../util.sh
+current_test=$(basename $(pwd))
+
+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 backup backup
+
+sleep 5
+
+expect_running_containers "3"
+
+docker run --rm -it \
+  -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)
+# 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 minio_backup_data:/minio_data \
+  alpine \
+  ash -c '[ $(find /minio_data/backup/ -type f | wc -l) = "1" ]'
+
+pass "Remote backups have not been deleted."
+
+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 -it \
+  -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 +1,43 @@
+#!/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
+sleep 5
+
+docker compose exec backup backup
+
+sleep 5
+
+expect_running_containers 3
+
+docker run --rm -it \
+  -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)
+# 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 ssh_backup_data:/ssh_data \
+  alpine \
+  ash -c '[ $(find /ssh_data/ -type f | wc -l) = "1" ]'
+
+pass "Remote backups have not been deleted."
+
+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
 
@@ -18,18 +20,18 @@ sleep 20
 docker exec $(docker ps -q -f name=backup) backup
 
 docker run --rm -it \
-  -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/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 +1,40 @@
+#!/bin/sh
+
+set -e
+
+cd "$(dirname "$0")"
+. ../util.sh
+current_test=$(basename $(pwd))
+
+docker compose up -d
+sleep 5
+
+docker compose exec backup backup
+
+sleep 5
+
+expect_running_containers "3"
+
+docker run --rm -it \
+  -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)
+# 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 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."
+
+docker compose down --volumes