Allow multiple schedules in the same container (#78)

* Allow mounting of config directory for multiple schedules

* Add docs for conf.d feature

* Fix behavior on multiple files

* Define default case first in entrypoint script

.circleci/config.yml

@@ -3,7 +3,7 @@ version: 2.1
 jobs:
   canary:
     machine:
-      image: ubuntu-1604:202007-01
+      image: ubuntu-2004:202201-02
     working_directory: ~/docker-volume-backup
     steps:
       - checkout
@@ -19,6 +19,7 @@ jobs:
           name: Run tests
           working_directory: ~/docker-volume-backup/test
           command: |
+            export GPG_TTY=$(tty)
             ./test.sh canary
 
   build:

Dockerfile

@@ -14,7 +14,7 @@ FROM alpine:3.15
 
 WORKDIR /root
 
-RUN apk add --update ca-certificates
+RUN apk add --no-cache ca-certificates
 
 COPY --from=builder /app/cmd/backup/backup /usr/bin/backup
 

README.md

@@ -16,16 +16,19 @@ It handles __recurring or one-off backups of Docker volumes__ to a __local direc
   - [One-off backups using Docker CLI](#one-off-backups-using-docker-cli)
 - [Configuration reference](#configuration-reference)
 - [How to](#how-to)
-  - [Stopping containers during backup](#stopping-containers-during-backup)
+  - [Stop containers during backup](#stop-containers-during-backup)
   - [Automatically pruning old backups](#automatically-pruning-old-backups)
   - [Send email notifications on failed backup runs](#send-email-notifications-on-failed-backup-runs)
   - [Customize notifications](#customize-notifications)
+  - [Run custom commands before / after backup](#run-custom-commands-before--after-backup)
   - [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)
   - [Using with Docker Swarm](#using-with-docker-swarm)
   - [Manually triggering a backup](#manually-triggering-a-backup)
   - [Update deprecated email configuration](#update-deprecated-email-configuration)
+  - [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)
 - [Recipes](#recipes)
   - [Backing up to AWS S3](#backing-up-to-aws-s3)
   - [Backing up to Filebase](#backing-up-to-filebase)
@@ -36,6 +39,7 @@ It handles __recurring or one-off backups of Docker volumes__ to a __local direc
   - [Running on a custom cron schedule](#running-on-a-custom-cron-schedule)
   - [Rotating away backups that are older than 7 days](#rotating-away-backups-that-are-older-than-7-days)
   - [Encrypting your backups using GPG](#encrypting-your-backups-using-gpg)
+  - [Using mysqldump to prepare the backup](#using-mysqldump-to-prepare-the-backup)
   - [Running multiple instances in the same setup](#running-multiple-instances-in-the-same-setup)
 - [Differences to `futurice/docker-volume-backup`](#differences-to-futuricedocker-volume-backup)
 
@@ -80,7 +84,8 @@ services:
       - data:/backup/my-app-backup:ro
       # Mounting the Docker socket allows the script to stop and restart
       # the container during backup. You can omit this if you don't want
-      # to stop the container
+      # to stop the container. In case you need to proxy the socket, you can
+      # also provide a location by setting `DOCKER_HOST` in the container
       - /var/run/docker.sock:/var/run/docker.sock:ro
       # If you mount a local directory or volume to `/archive` a local
       # copy of the backup will be stored there. You can override the
@@ -277,6 +282,27 @@ You can populate below template according to your requirements and use it as you
 
 # BACKUP_STOP_CONTAINER_LABEL="service1"
 
+########### EXECUTING COMMANDS IN CONTAINERS PRE/POST BACKUP
+
+# 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'.
+# Several options exist for controlling this feature:
+
+# By default, any output of such a command is suppressed. If this value
+# is configured to be "true", command execution output will be forwarded to
+# the backup container's stdout and stderr.
+
+# EXEC_FORWARD_OUTPUT="true"
+
+# Without any further configuration, all commands defined in labels will be
+# run before and after a backup. If you need more fine grained control, you
+# can use this option to set a label that will be used for narrowing down
+# the set of eligible containers. When set, an eligible container will also need
+# to be labeled as `docker-volume-backup.exec-label=database`.
+
+# EXEC_LABEL="database"
+
 ########### NOTIFICATIONS
 
 # Notifications (email, Slack, etc.) can be sent out when a backup run finishes.
@@ -297,6 +323,13 @@ You can populate below template according to your requirements and use it as you
 
 # NOTIFICATION_LEVEL="error"
 
+########### DOCKER HOST
+
+# If you are interfacing with Docker via TCP you can set the Docker host here
+# instead of mounting the Docker socket as a volume. This is unset by default.
+
+# DOCKER_HOST="tcp://docker_socket_proxy:2375"
+
 ########### EMAIL NOTIFICATIONS
 
 # ************************************************************************
@@ -335,7 +368,7 @@ You can work around this by either updating `docker-compose` or unquoting your c
 
 ## How to
 
-### Stopping containers during backup
+### Stop containers during backup
 
 In many cases, it will be desirable to stop the services that are consuming the volume you want to backup in order to ensure data integrity.
 This image can automatically stop and restart containers and services (in case you are running Docker in Swarm mode).
@@ -435,6 +468,63 @@ 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
+
+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.
+Such commands are defined by specifying the command in a `docker-volume-backup.exec-[pre|post]` label.
+
+Taking a database dump using `mysqldump` would look like this:
+
+```yml
+version: '3'
+
+services:
+  # ... define other services using the `data` volume here
+  database:
+    image: mariadb
+    volumes:
+      - backup_data:/tmp/backups
+    labels:
+      - docker-volume-backup.exec-pre=/bin/sh -c 'mysqldump --all-databases > /backups/dump.sql'
+
+volumes:
+  backup_data:
+```
+
+Due to Docker limitations, you currently cannot use any kind of redirection in these commands unless you pass the command to `/bin/sh -c` or similar.
+I.e. instead of using `echo "ok" > ok.txt` you will need to use `/bin/sh -c 'echo "ok" > ok.txt'`.
+
+If you need fine grained control about which container's commands are run, you can use the `EXEC_LABEL` configuration on your `docker-volume-backup` container:
+
+```yml
+version: '3'
+
+services:
+  database:
+    image: mariadb
+    volumes:
+      - backup_data:/tmp/backups
+    labels:
+      - docker-volume-backup.exec-pre=/bin/sh -c 'mysqldump --all-databases > /tmp/volume/dump.sql'
+      - docker-volume-backup.exec-label=database
+
+  backup:
+    image: offen/docker-volume-backup:latest
+    environment:
+      EXEC_LABEL: database
+    volumes:
+      - data:/backup/dump:ro
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+
+volumes:
+  backup_data:
+```
+
+
+The backup procedure is guaranteed to wait for all `pre` commands to finish.
+However there are no guarantees about the order in which they are run, which could also happen concurrently.
+
 ### Encrypting your backup using GPG
 
 The image supports encrypting backups using GPG out of the box.
@@ -466,6 +556,26 @@ In case you need to restore a volume from a backup, the most straight forward pr
 
 Depending on your setup and the application(s) you are running, this might involve other steps to be taken still.
 
+---
+
+If you want to rollback an entire volume to an earlier backup snapshot (recommended for database volumes):
+
+- Trigger a manual backup if necessary (see `Manually triggering a backup`).
+- Stop the container(s) that are using the volume.
+- If volume was initially created using docker-compose, find out exact volume name using:
+  ```console
+  docker volume ls
+  ```
+- Remove existing volume (the example assumes it's named `data`):
+  ```console
+  docker volume rm data
+  ```
+- Create new volume with the same name and restore a snapshot:
+  ```console
+  docker run --rm -it -v data:/backup/my-app-backup -v /path/to/local_backups:/archive:ro alpine tar -xvzf /archive/full_backup_filename.tar.gz
+  ```
+- Restart the container(s) that are using the volume.
+
 ### Set the timezone the container runs in
 
 By default a container based on this image will run in the UTC timezone.
@@ -535,6 +645,41 @@ After:
 NOTIFICATION_URLS=smtp://me:secret@posteo.de:587/?fromAddress=no-reply@example.com&toAddresses=you@example.com
 ```
 
+### Using a custom Docker host
+
+If you are interfacing with Docker via TCP, set `DOCKER_HOST` to the correct URL.
+```ini
+DOCKER_HOST=tcp://docker_socket_proxy:2375
+```
+
+In case you are using a socket proxy, it must support `GET` and `POST` requests to the `/containers` endpoint. If you are using Docker Swarm, it must also support the `/services` endpoint. If you are using pre/post backup commands, it must also support the `/exec` endpoint.
+
+### Run multiple backup schedules in the same container
+
+Multiple backup schedules with different configuration can be configured by mounting an arbitrary number of configuration files (using the `.env` format) into `/etc/dockervolumebackup/conf.d`:
+
+```
+version: '3'
+
+services:
+  # ... define other services using the `data` volume here
+  backup:
+    image: offen/docker-volume-backup:latest
+    volumes:
+      - data:/backup/my-app-backup:ro
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+      - ./configuration:/etc/dockervolumebackup/conf.d
+
+volumes:
+  data:
+```
+
+A separate cronjob will be created for each config file.
+If a configuration value is set both in the global environment as well as in the config file, the config file will take precedence.
+The `backup` command expects to run on an exclusive lock, so it is your responsibility to make sure the invocations do not overlap.
+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.
+
 ## Recipes
 
 This section lists configuration for some real-world use cases that you can mix and match according to your needs.
@@ -738,6 +883,32 @@ volumes:
   data:
 ```
 
+### Using mysqldump to prepare the backup
+
+```yml
+version: '3'
+
+services:
+  database:
+    image: mariadb:latest
+    labels:
+      - docker-volume-backup.exec-pre=/bin/sh -c 'mysqldump -psecret --all-databases > /tmp/dumps/dump.sql'
+    volumes:
+      - app_data:/tmp/dumps
+  backup:
+    image: offen/docker-volume-backup:latest
+    environment:
+      BACKUP_FILENAME: db.tar.gz
+      BACKUP_CRON_EXPRESSION: "0 2 * * *"
+    volumes:
+      - ./local:/archive
+      - data:/backup/data:ro
+      - /var/run/docker.sock:/var/run/docker.sock
+
+volumes:
+  data:
+```
+
 ### Running multiple instances in the same setup
 
 ```yml
@@ -779,12 +950,12 @@ This image is heavily inspired by `futurice/docker-volume-backup`. We decided to
 
 - The original image is based on `ubuntu` and requires additional tools, making it heavy.
 This version is roughly 1/25 in compressed size (it's ~12MB).
-- The original image uses a shell script, when this version is written in Go, which makes it easier to extend and maintain (more verbose too).
+- The original image uses a shell script, when this version is written in Go.
 - The original image proposed to handle backup rotation through AWS S3 lifecycle policies.
 This image adds the option to rotate away old backups through the same command so this functionality can also be offered for non-AWS storage backends like MinIO.
 Local copies of backups can also be pruned once they reach a certain age.
 - InfluxDB specific functionality from the original image was removed.
 - `arm64` and `arm/v7` architectures are supported.
 - Docker in Swarm mode is supported.
-- Notifications on failed backups are supported
-- IAM authentication through instance profiles is supported
+- Notifications on finished backups are supported.
+- IAM authentication through instance profiles is supported.

cmd/backup/archive.go

@@ -0,0 +1,142 @@
+// Copyright 2022 - Offen Authors <hioffen@posteo.de>
+// SPDX-License-Identifier: MPL-2.0
+
+// Portions of this file are taken from package `targz`, Copyright (c) 2014 Fredrik Wallgren
+// Licensed under the MIT License: https://github.com/walle/targz/blob/57fe4206da5abf7dd3901b4af3891ec2f08c7b08/LICENSE
+
+package main
+
+import (
+	"archive/tar"
+	"compress/gzip"
+	"fmt"
+	"io"
+	"io/fs"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+)
+
+func createArchive(inputFilePath, outputFilePath string) error {
+	inputFilePath = stripTrailingSlashes(inputFilePath)
+	inputFilePath, outputFilePath, err := makeAbsolute(inputFilePath, outputFilePath)
+	if err != nil {
+		return fmt.Errorf("createArchive: error transposing given file paths: %w", err)
+	}
+	if err := os.MkdirAll(filepath.Dir(outputFilePath), 0755); err != nil {
+		return fmt.Errorf("createArchive: error creating output file path: %w", err)
+	}
+
+	if err := compress(inputFilePath, outputFilePath, filepath.Dir(inputFilePath)); err != nil {
+		return fmt.Errorf("createArchive: error creating archive: %w", err)
+	}
+
+	return nil
+}
+
+func stripTrailingSlashes(path string) string {
+	if len(path) > 0 && path[len(path)-1] == '/' {
+		path = path[0 : len(path)-1]
+	}
+
+	return path
+}
+
+func makeAbsolute(inputFilePath, outputFilePath string) (string, string, error) {
+	inputFilePath, err := filepath.Abs(inputFilePath)
+	if err == nil {
+		outputFilePath, err = filepath.Abs(outputFilePath)
+	}
+
+	return inputFilePath, outputFilePath, err
+}
+
+func compress(inPath, outFilePath, subPath string) error {
+	file, err := os.Create(outFilePath)
+	if err != nil {
+		return fmt.Errorf("compress: error creating out file: %w", err)
+	}
+
+	prefix := path.Dir(outFilePath)
+	gzipWriter := gzip.NewWriter(file)
+	tarWriter := tar.NewWriter(gzipWriter)
+
+	var paths []string
+	if err := filepath.WalkDir(inPath, func(path string, di fs.DirEntry, err error) error {
+		paths = append(paths, path)
+		return err
+	}); err != nil {
+		return fmt.Errorf("compress: error walking filesystem tree: %w", err)
+	}
+
+	for _, p := range paths {
+		if err := writeTarGz(p, tarWriter, prefix); err != nil {
+			return fmt.Errorf("compress error writing %s to archive: %w", p, err)
+		}
+	}
+
+	err = tarWriter.Close()
+	if err != nil {
+		return fmt.Errorf("compress: error closing tar writer: %w", err)
+	}
+
+	err = gzipWriter.Close()
+	if err != nil {
+		return fmt.Errorf("compress: error closing gzip writer: %w", err)
+	}
+
+	err = file.Close()
+	if err != nil {
+		return fmt.Errorf("compress: error closing file: %w", err)
+	}
+
+	return nil
+}
+
+func writeTarGz(path string, tarWriter *tar.Writer, prefix string) error {
+	fileInfo, err := os.Lstat(path)
+	if err != nil {
+		return fmt.Errorf("writeTarGz: error getting file infor for %s: %w", path, err)
+	}
+
+	if fileInfo.Mode()&os.ModeSocket == os.ModeSocket {
+		return nil
+	}
+
+	var link string
+	if fileInfo.Mode()&os.ModeSymlink == os.ModeSymlink {
+		var err error
+		if link, err = os.Readlink(path); err != nil {
+			return fmt.Errorf("writeTarGz: error resolving symlink %s: %w", path, err)
+		}
+	}
+
+	header, err := tar.FileInfoHeader(fileInfo, link)
+	if err != nil {
+		return fmt.Errorf("writeTarGz: error getting file info header: %w", err)
+	}
+	header.Name = strings.TrimPrefix(path, prefix)
+
+	err = tarWriter.WriteHeader(header)
+	if err != nil {
+		return fmt.Errorf("writeTarGz: error writing file info header: %w", err)
+	}
+
+	if !fileInfo.Mode().IsRegular() {
+		return nil
+	}
+
+	file, err := os.Open(path)
+	if err != nil {
+		return fmt.Errorf("writeTarGz: error opening %s: %w", path, err)
+	}
+	defer file.Close()
+
+	_, err = io.Copy(tarWriter, file)
+	if err != nil {
+		return fmt.Errorf("writeTarGz: error copying %s to tar writer: %w", path, err)
+	}
+
+	return nil
+}

cmd/backup/config.go

@@ -39,4 +39,6 @@ type Config struct {
 	WebdavPath                 string        `split_words:"true" default:"/"`
 	WebdavUsername             string        `split_words:"true"`
 	WebdavPassword             string        `split_words:"true"`
+	ExecLabel                  string        `split_words:"true"`
+	ExecForwardOutput          bool          `split_words:"true"`
 }

cmd/backup/exec.go

@@ -0,0 +1,122 @@
+// Copyright 2022 - Offen Authors <hioffen@posteo.de>
+// SPDX-License-Identifier: MPL-2.0
+
+package main
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"strings"
+	"sync"
+
+	"github.com/cosiner/argv"
+	"github.com/docker/docker/api/types"
+	"github.com/docker/docker/api/types/filters"
+	"github.com/docker/docker/pkg/stdcopy"
+)
+
+func (s *script) exec(containerRef string, command string) ([]byte, []byte, error) {
+	args, _ := argv.Argv(command, nil, nil)
+	execID, err := s.cli.ContainerExecCreate(context.Background(), containerRef, types.ExecConfig{
+		Cmd:          args[0],
+		AttachStdin:  true,
+		AttachStderr: true,
+	})
+	if err != nil {
+		return nil, nil, fmt.Errorf("exec: error creating container exec: %w", err)
+	}
+
+	resp, err := s.cli.ContainerExecAttach(context.Background(), execID.ID, types.ExecStartCheck{})
+	if err != nil {
+		return nil, nil, fmt.Errorf("exec: error attaching container exec: %w", err)
+	}
+	defer resp.Close()
+
+	var outBuf, errBuf bytes.Buffer
+	outputDone := make(chan error)
+
+	go func() {
+		_, err := stdcopy.StdCopy(&outBuf, &errBuf, resp.Reader)
+		outputDone <- err
+	}()
+
+	select {
+	case err := <-outputDone:
+		if err != nil {
+			return nil, nil, fmt.Errorf("exec: error demultiplexing output: %w", err)
+		}
+		break
+	}
+
+	stdout, err := ioutil.ReadAll(&outBuf)
+	if err != nil {
+		return nil, nil, fmt.Errorf("exec: error reading stdout: %w", err)
+	}
+	stderr, err := ioutil.ReadAll(&errBuf)
+	if err != nil {
+		return nil, nil, fmt.Errorf("exec: error reading stderr: %w", err)
+	}
+
+	res, err := s.cli.ContainerExecInspect(context.Background(), execID.ID)
+	if err != nil {
+		return nil, nil, fmt.Errorf("exec: error inspecting container exec: %w", err)
+	}
+
+	if res.ExitCode > 0 {
+		return stdout, stderr, fmt.Errorf("exec: running command exited %d", res.ExitCode)
+	}
+
+	return stdout, stderr, nil
+}
+
+func (s *script) runLabeledCommands(label string) error {
+	f := []filters.KeyValuePair{
+		{Key: "label", Value: label},
+	}
+	if s.c.ExecLabel != "" {
+		f = append(f, filters.KeyValuePair{
+			Key:   "label",
+			Value: fmt.Sprintf("docker-volume-backup.exec-label=%s", s.c.ExecLabel),
+		})
+	}
+	containersWithCommand, err := s.cli.ContainerList(context.Background(), types.ContainerListOptions{
+		Quiet:   true,
+		Filters: filters.NewArgs(f...),
+	})
+	if err != nil {
+		return fmt.Errorf("runLabeledCommands: error querying for containers: %w", err)
+	}
+
+	if len(containersWithCommand) == 0 {
+		return nil
+	}
+
+	wg := sync.WaitGroup{}
+	wg.Add(len(containersWithCommand))
+
+	var cmdErrors []error
+	for _, container := range containersWithCommand {
+		go func(c types.Container) {
+			cmd, _ := c.Labels[label]
+			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 err != nil {
+				cmdErrors = append(cmdErrors, err)
+			}
+			if s.c.ExecForwardOutput {
+				os.Stderr.Write(stderr)
+				os.Stdout.Write(stdout)
+			}
+			wg.Done()
+		}(container)
+	}
+
+	wg.Wait()
+	if len(cmdErrors) != 0 {
+		return join(cmdErrors...)
+	}
+	return nil
+}

cmd/backup/main.go

@@ -38,6 +38,13 @@ func main() {
 	}()
 
 	s.must(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

cmd/backup/script.go

@@ -23,7 +23,6 @@ import (
 	"github.com/docker/docker/client"
 	"github.com/kelseyhightower/envconfig"
 	"github.com/leekchan/timeutil"
-	"github.com/m90/targz"
 	"github.com/minio/minio-go/v7"
 	"github.com/minio/minio-go/v7/pkg/credentials"
 	"github.com/otiai10/copy"
@@ -73,7 +72,7 @@ func newScript() (*script, error) {
 
 	s.registerHook(hookLevelPlumbing, func(error) error {
 		s.stats.EndTime = time.Now()
-		s.stats.TookTime = s.stats.EndTime.Sub(s.stats.EndTime)
+		s.stats.TookTime = s.stats.EndTime.Sub(s.stats.StartTime)
 		return nil
 	})
 
@@ -90,7 +89,8 @@ func newScript() (*script, error) {
 	s.file = timeutil.Strftime(&s.stats.StartTime, s.file)
 
 	_, err := os.Stat("/var/run/docker.sock")
-	if !os.IsNotExist(err) {
+	_, dockerHostSet := os.LookupEnv("DOCKER_HOST")
+	if !os.IsNotExist(err) || dockerHostSet {
 		cli, err := client.NewClientWithOpts(client.FromEnv, client.WithAPIVersionNegotiation())
 		if err != nil {
 			return nil, fmt.Errorf("newScript: failed to create docker client")
@@ -212,6 +212,22 @@ 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.
@@ -363,7 +379,7 @@ func (s *script) takeBackup() error {
 		s.logger.Infof("Removed tar file `%s`.", tarFile)
 		return nil
 	})
-	if err := targz.Compress(backupSources, tarFile); err != nil {
+	if err := createArchive(backupSources, tarFile); err != nil {
 		return fmt.Errorf("takeBackup: error compressing backup folder: %w", err)
 	}
 

entrypoint.sh

@@ -5,10 +5,21 @@
 
 set -e
 
-BACKUP_CRON_EXPRESSION="${BACKUP_CRON_EXPRESSION:-@daily}"
+if [ ! -d "/etc/dockervolumebackup/conf.d" ]; then
+  BACKUP_CRON_EXPRESSION="${BACKUP_CRON_EXPRESSION:-@daily}"
 
-echo "Installing cron.d entry with expression $BACKUP_CRON_EXPRESSION."
-echo "$BACKUP_CRON_EXPRESSION backup 2>&1" | crontab -
+  echo "Installing cron.d entry with expression $BACKUP_CRON_EXPRESSION."
+  echo "$BACKUP_CRON_EXPRESSION backup 2>&1" | crontab -
+else
+  echo "/etc/dockervolumebackup/conf.d was found, using configuration files from this directory."
+
+  for file in /etc/dockervolumebackup/conf.d/*; do
+    source $file
+    BACKUP_CRON_EXPRESSION="${BACKUP_CRON_EXPRESSION:-@daily}"
+    echo "Appending cron.d entry with expression $BACKUP_CRON_EXPRESSION and configuration file $file"
+    (crontab -l; echo "$BACKUP_CRON_EXPRESSION /bin/sh -c 'set -a; source $file; set +a && backup' 2>&1") | crontab -
+  done
+fi
 
 echo "Starting cron in foreground."
 crond -f -l 8

go.mod

@@ -4,11 +4,11 @@ go 1.17
 
 require (
 	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/m90/targz v0.0.0-20220208141135-d3baeef59a97
 	github.com/minio/minio-go/v7 v7.0.16
 	github.com/otiai10/copy v1.7.0
 	github.com/sirupsen/logrus v1.8.1

go.sum

@@ -208,6 +208,8 @@ github.com/coreos/go-systemd/v22 v22.1.0/go.mod h1:xO0FLkIi5MaZafQlIrOotqXZ90ih+
 github.com/coreos/go-systemd/v22 v22.3.2/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
 github.com/coreos/pkg v0.0.0-20160727233714-3ac0863d7acf/go.mod h1:E3G3o1h8I7cfcXa63jLwjI0eiQQMgzzUDFVpN/nH/eA=
 github.com/coreos/pkg v0.0.0-20180928190104-399ea9e2e55f/go.mod h1:E3G3o1h8I7cfcXa63jLwjI0eiQQMgzzUDFVpN/nH/eA=
+github.com/cosiner/argv v0.1.0 h1:BVDiEL32lwHukgJKP87btEPenzrrHUjajs/8yzaqcXg=
+github.com/cosiner/argv v0.1.0/go.mod h1:EusR6TucWKX+zFgtdUsKT2Cvg45K5rtpCcWz4hK06d8=
 github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
 github.com/cpuguy83/go-md2man/v2 v2.0.0/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
 github.com/creack/pty v1.1.7/go.mod h1:lj5s0c3V2DBrqTV7llrYr5NG6My20zk30Fl46Y7DoTY=
@@ -450,8 +452,6 @@ github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/leekchan/timeutil v0.0.0-20150802142658-28917288c48d h1:2puqoOQwi3Ai1oznMOsFIbifm6kIfJaLLyYzWD4IzTs=
 github.com/leekchan/timeutil v0.0.0-20150802142658-28917288c48d/go.mod h1:hO90vCP2x3exaSH58BIAowSKvV+0OsY21TtzuFGHON4=
 github.com/leodido/go-urn v1.2.0/go.mod h1:+8+nEpDfqqsY+g338gtMEUOtuK+4dEMhiQEgxpxOKII=
-github.com/m90/targz v0.0.0-20220208141135-d3baeef59a97 h1:Uc/WzUKI/zvhkqIzk5TyaPE6AY1SD1DWGc7RV7cky4s=
-github.com/m90/targz v0.0.0-20220208141135-d3baeef59a97/go.mod h1:YZK3bSO/oVlk9G+v00BxgzxW2Us4p/R4ysHOBjk0fJI=
 github.com/magiconair/properties v1.8.0/go.mod h1:PppfXfuXeibc/6YijjN8zIbojt8czPbwD3XqdrwzmxQ=
 github.com/magiconair/properties v1.8.1/go.mod h1:PppfXfuXeibc/6YijjN8zIbojt8czPbwD3XqdrwzmxQ=
 github.com/mailru/easyjson v0.0.0-20190403194419-1ea4449da983/go.mod h1:C1wdFJiN94OJF2b5HbByQZoLdCWB1Yqtg26g4irojpc=

test/cli/run.sh

@@ -44,7 +44,7 @@ docker run --rm \
   --env BACKUP_FILENAME=test.tar.gz \
   --env "BACKUP_FROM_SNAPSHOT=true" \
   --entrypoint backup \
-  offen/docker-volume-backup:$TEST_VERSION
+  offen/docker-volume-backup:${TEST_VERSION:-canary}
 
 docker run --rm -it \
   -v backup_data:/data alpine \

test/commands/.gitignore

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

test/commands/docker-compose.yml

@@ -0,0 +1,36 @@
+version: '3.8'
+
+services:
+  database:
+    image: mariadb:10.7
+    deploy:
+      restart_policy:
+        condition: on-failure
+    environment:
+      MARIADB_ROOT_PASSWORD: test
+      MARIADB_DATABASE: backup
+    labels:
+      - 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.exec-label=test
+    volumes:
+      - app_data:/tmp/volume
+
+  backup:
+    image: offen/docker-volume-backup:${TEST_VERSION:-canary}
+    deploy:
+      restart_policy:
+        condition: on-failure
+    environment:
+      BACKUP_FILENAME: test.tar.gz
+      BACKUP_CRON_EXPRESSION: 0 0 5 31 2 ?
+      EXEC_LABEL: test
+      EXEC_FORWARD_OUTPUT: "true"
+    volumes:
+      - archive:/archive
+      - app_data:/backup/data:ro
+      - /var/run/docker.sock:/var/run/docker.sock
+
+volumes:
+  app_data:
+  archive:

test/commands/run.sh

@@ -0,0 +1,62 @@
+#!/bin/sh
+
+set -e
+
+cd $(dirname $0)
+
+
+docker-compose up -d
+sleep 30 # mariadb likes to take a bit before responding
+
+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."
+  exit 1
+fi
+echo "[TEST:PASS] Found expected file."
+
+if [ -f ./backup/data/post.txt ]; then
+  echo "[TEST:FAIL] File created in post command was present in backup."
+  exit 1
+fi
+echo "[TEST:PASS] Did not find unexpected file."
+
+docker-compose down --volumes
+sudo rm -rf ./local
+
+
+echo "[TEST: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."
+  sleep 1
+done
+
+sleep 20
+
+docker exec $(docker ps -q -f name=backup) backup
+
+sudo cp -r $(docker volume inspect --format='{{ .Mountpoint }}' test_stack_archive) ./local
+
+tar -xvf ./local/test.tar.gz
+if [ ! -f ./backup/data/dump.sql ]; then
+  echo "[TEST:FAIL] Could not find file written by pre command."
+  exit 1
+fi
+echo "[TEST:PASS] Found expected file."
+
+if [ -f ./backup/data/post.txt ]; then
+  echo "[TEST:FAIL] File created in post command was present in backup."
+  exit 1
+fi
+echo "[TEST:PASS] Did not find unexpected file."
+
+docker stack rm test_stack
+docker swarm leave --force

test/compose/docker-compose.yml

@@ -21,8 +21,8 @@ services:
     volumes:
       - webdav_backup_data:/var/lib/dav
 
-  backup: &default_backup_service
-    image: offen/docker-volume-backup:${TEST_VERSION}
+  backup:
+    image: offen/docker-volume-backup:${TEST_VERSION:-canary}
     hostname: hostnametoken
     depends_on:
       - minio

test/compose/run.sh

@@ -27,12 +27,12 @@ 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 -xf /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 -xf /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 /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 --yes --passphrase-fd 0 ./local/test-hostnametoken.tar.gz.gpg > ./local/decrypted.tar.gz
+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

test/confd/.gitignore

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

test/confd/backup.env

@@ -0,0 +1,2 @@
+BACKUP_FILENAME="conf.tar.gz"
+BACKUP_CRON_EXPRESSION="*/1 * * * *"

test/confd/docker-compose.yml

@@ -0,0 +1,22 @@
+version: '3'
+
+services:
+  backup:
+    image: offen/docker-volume-backup:${TEST_VERSION:-canary}
+    restart: always
+    volumes:
+      - ./local:/archive
+      - app_data:/backup/app_data:ro
+      - ./backup.env:/etc/dockervolumebackup/conf.d/00backup.env
+      - ./never.env:/etc/dockervolumebackup/conf.d/10never.env
+      - /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/confd/never.env

@@ -0,0 +1,2 @@
+BACKUP_FILENAME="never.tar.gz"
+BACKUP_CRON_EXPRESSION="0 0 5 31 2 ?"

test/confd/run.sh

@@ -0,0 +1,26 @@
+#!/bin/sh
+
+set -e
+
+cd $(dirname $0)
+
+mkdir -p local
+
+docker-compose up -d
+
+# sleep until a backup is guaranteed to have happened on the 1 minute schedule
+sleep 100
+
+docker-compose down --volumes
+
+if [ ! -f ./local/conf.tar.gz ]; then
+  echo "[TEST:FAIL] Config from file was not used."
+  exit 1
+fi
+echo "[TEST:PASS] Config from file was used."
+
+if [ -f ./local/never.tar.gz ]; then
+  echo "[TEST:FAIL] Unexpected file was found."
+  exit 1
+fi
+echo "[TEST:PASS] Unexpected cron did not run."

test/notifications/docker-compose.yml

@@ -1,8 +1,8 @@
 version: '3'
 
 services:
-  backup: &default_backup_service
-    image: offen/docker-volume-backup:${TEST_VERSION}
+  backup:
+    image: offen/docker-volume-backup:${TEST_VERSION:-canary}
     restart: always
     environment:
       BACKUP_FILENAME: test.tar.gz

test/ownership/.gitignore

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

test/ownership/docker-compose.yml

@@ -0,0 +1,27 @@
+version: '3'
+
+services:
+  db:
+    image: postgres:14-alpine
+    restart: unless-stopped
+    labels:
+      - docker-volume-backup.stop-during-backup=true
+    volumes:
+      - postgres_data:/var/lib/postgresql/data
+    environment:
+      - POSTGRES_PASSWORD=1FHJMSwt0yhIN1zS7I4DilGUhThBKq0x
+      - POSTGRES_USER=test
+      - POSTGRES_DB=test
+
+  backup:
+    image: offen/docker-volume-backup:${TEST_VERSION}
+    restart: always
+    environment:
+      BACKUP_FILENAME: backup.tar.gz
+    volumes:
+      - postgres_data:/backup/postgres:ro
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+      - ./local:/archive
+
+volumes:
+  postgres_data:

test/ownership/run.sh

@@ -0,0 +1,28 @@
+#!/bin/sh
+# This test refers to https://github.com/offen/docker-volume-backup/issues/71
+
+set -e
+
+cd $(dirname $0)
+
+mkdir -p local
+
+docker-compose up -d
+sleep 5
+
+docker-compose exec backup backup
+
+sudo tar --same-owner -xvf ./local/backup.tar.gz -C /tmp
+
+sudo find /tmp/backup/postgres > /dev/null
+echo "[TEST:PASS] Backup contains files at expected location"
+
+for file in $(sudo find /tmp/backup/postgres); do
+  if [ "$(sudo stat -c '%u:%g' $file)" != "70:70" ]; then
+    echo "[TEST:FAIL] Unexpected file ownership for $file: $(sudo stat -c '%u:%g' $file)"
+    exit 1
+  fi
+done
+echo "[TEST:PASS] All files and directories in backup preserved their ownership."
+
+docker-compose down --volumes

test/swarm/docker-compose.yml

@@ -18,8 +18,8 @@ services:
     volumes:
       - backup_data:/data
 
-  backup: &default_backup_service
-    image: offen/docker-volume-backup:${TEST_VERSION}
+  backup:
+    image: offen/docker-volume-backup:${TEST_VERSION:-canary}
     depends_on:
       - minio
     deploy:
@@ -49,7 +49,7 @@ services:
         condition: on-failure
 
   pg:
-    image: postgres:12.2-alpine
+    image: postgres:14-alpine
     environment:
       POSTGRES_PASSWORD: example
     labels: