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Containerized dar-backup: run automated, verifiable dar backups in Docker, Kubernetes, or on your local machine.

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📦 dar-backup image for container backups and more

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🗄️ dar-backup-image

dar-backup-image is a Docker image that bundles the powerful dar (Disk ARchiver) utility with the robust Python wrapper dar-backup. Together, they provide a flexible, automated, and verifiable backup solution suited for long-term data retention.

This image makes it easy to run dar-backup in a clean, isolated container environment — perfect for use in cron jobs, systemd timers, or CI pipelines. Whether you're backing up from FUSE-based cloud storage or verifying years-old archives, this image delivers consistent, reproducible results without requiring dar or Python tooling on the host.

At its core is dar-backup, a Python-powered CLI that wraps dar and par2 for reliable full, differential, and incremental backups. It validates archives, performs restore tests, manages catalog databases, and optionally generates redundancy files to protect against bit rot.

🔧 Highlights

Automated backup logic with dar-backup: tested, restore-verified, and redundancy-enhanced

Stateless and portable: no installation required on the host system

Ideal for FUSE filesystems: works without root, designed for user-space storage

Includes par2 for integrity protection

Ready for CI / cron / systemd: just mount volumes and go

The default entrypoint of this image is dar-backup, meaning any docker run invocation without a command will start dar-backup directly. You can also run dar, par2, or a shell interactively by overriding the entrypoint.

Use dar-backup-image to centralize and simplify your backup operations — with restore confidence built in.

📑 Table of Contents

Builds uploaded to Docker Hub

Tag dar-backupversion Git Revision Docker Hub
0.5.11 0.8.2 30f25b5 tag:0.5.11
0.5.10 0.8.1 1d684b9 tag:0.5.10
0.5.9 0.8.1 34c6e68 tag:0.5.9
0.5.8 0.8.0 500d801 tag:0.5.8
0.5.7 0.8.0 ddf8afb tag:0.5.7

🔧 Hands-on Demo: dar-backup in a Container

Curious how it all works in practice?

Check out the 📄 step-by-step demo, which walks through:

  • A full backup from mounted directories
  • Archive listing and contents inspection
  • Selective file restore (e.g., .JPG only)
  • Output logs, par2 generation, and verification

All performed using docker run — no host installation required.

Useful links

Topic Link
dar-backup dar-backup on Github
dar-backup-image dar-backup-image
Docker Hub repo Docker Hub
dar Disk ARchive

License

dar-backup-imageis licensed under GPL 3 or later.

If you are unfamiliar with that license, take a look at the LICENSE file in this repo

Docker Hub image repo

You can see publicly available dar-backup docker images on Docker Hub.

Those fond of curl can do this:

curl -s https://hub.docker.com/v2/repositories/per2jensen/dar-backup/tags | jq '.results[].name'

Description

A minimal, Dockerized backup runner using dar (Disk ARchive) and dar-backup, ready for automated or manual archive creation and restore.

This is early, the dar-backup images are not tested well, do not trust it too much. It will mature over time :-)

This image includes:

  • dar
  • par2
  • python3
  • gosu
  • dar-backup (my dar Python based wrapper)
  • Clean, minimal Ubuntu 24.04 base (~170 MB)
  • CIS-aligned permissions and user-drop via gosu

How to test

# make new base and development image
make all-dev

# run FULL, DIFF and INCR backups in a temp directory
make test

Two images are built:

  1. A base image which currently is a slimmed down ubuntu 24.04 image

  2. dar-backup image is installed on top of the base image

🔧 Image Tags

Some images are put on DockerHub.

The Release procedure results in two things:

🐳 tagging strategy

For now I am not using latest, as the images have not yet demonstrated their quality.

I am currently going with:

Tag Description Docker Hub Example Usage
:0.x.y Versioned releases following semantic versioning ✅ Yes docker pull per2jensen/dar-backup:0.5.6
:stable Latest "good" and trusted version; perhaps :rc ✅ Yes docker pull per2jensen/dar-backup:stable
:dev Development version; may be broken or incomplete ❌ No docker run dar-backup:dev

🧰 Volumes / Runtime Configuration

The default dar-backup.conf baked into the image assumes the directories mentioned below.

The locations should be mounted with actual directories on your machine for backups.

Directories in file system Directories in container Purpose
/some/dir/to/backup/ /data Source directory for backup
/keep/backups/here/ /backup dar archives and .par2 files are put here
/restore/tests/ /restore Optional restore target
/backup/definitions/ /backup.d Contains backup definition files

The mapping between physical directories on your file system and the expected directories inside the container is performed by the -v /physical/dir:/container/dir options (see example below).

🚀 Usage Example

Determine if you want to built an image yourself, or use one of mine from Docker Hub.

# make a container
$ make FINAL_VERSION=dev DAR_BACKUP_VERSION=0.8.0 dev  # make a local development image

# check
$ docker images |grep "dev"
dar-backup              dev           e72a7fd82a4b   19 seconds ago   174MB

# Set IMAGE to your own
export IMAGE=dar-backup:dev  # your own locally build image

# Or set IMAGE to one of mine on Docker Hub
export IMAGE=per2jensen/dar-backup:0.5.6

Now run dar-backup in the container

# Run it (from script or manually)
# Configuration
export DATA_DIR=/tmp/test-data          # the data to backup
export BACKUP_DIR=/tmp/test-backups     # the directory that keeps the backups
export RESTORE_DIR=/tmp/test-restore    # the directory used for restore tests during backup verification
export BACKUP_D_DIR=/tmp/test-backup.d  # the directory keeping the `backup definitions`

docker run --rm \
  -e RUN_AS_UID=$(id -u) \
  -v "$DATA_DIR":/data \
  -v "$BACKUP_DIR":/backup \
  -v "$RESTORE_DIR":/restore \
  -v "$BACKUP_D_DIR":/backup.d \
  "$IMAGE" \
  -F --log-stdout --config /etc/dar-backup/dar-backup.conf

The --config option to dar-backup is referencing the baked-in config file. In other words, the config file is part of the container image. To use another config file you have multiple options:

  • Modify the baked-in and build a new image.
  • Use --config option to point to another (for example: /backup/dar-backup.conf, which in the example above means you physically put it on "$BACKUP_DIR"/dar-backup.conf)

The container uses gosu to drop root privileges. Pass -e RUN_AS_UID=$(id -u) to run as your own user inside the container.

run-backup.sh

This script runs a backup using a dar-backup Docker image.

It runs a backup based on the specified type (FULL, DIFF, INCR) with the following features:

1

Using the baked in dar-backup.conf file (se more here).

2

Uses the .darrc file from the PyPI package added to the image, see image details here

.darrc contents

3

It print log messages to stdout.

4

Expected directory structure when running this script:

   WORKDIR/
     ├── backups/           # Where backups are stored
     ├── backup.d/          # Backup definitions
     ├── data/              # Data to backup
     └── restore/           # Where restored files will be placed

If envvar WORKDIR is set, the script uses that as the base directory.

If WORKDIR is not set, the script uses the directory where the script is located as the base directory.

More info on backup definitions in general

View supplied default backup definition

5

If IMAGE is not set, the script defaults to dar-backup:dev.

You can see available images on [Docker Hub here)(https://hub.docker.com/r/per2jensen/dar-backup/tags)

If RUN_AS_UID is not set, it defaults to the current user's UID. - running the script as root is not allowed, the script will exit with an error.

6

You can configure the directory layout by setting the following environment variables:

  • DAR_BACKUP_DIR: Directory for backups (default: WORKDIR/backups)

  • DAR_BACKUP_DATA_DIR: Directory for data to backup (default: WORKDIR/data)

  • DAR_BACKUP_D_DIR: Directory for backup definitions (default: WORKDIR/backup.d)

  • DAR_BACKUP_RESTORE_DIR: Directory for restored files (default: WORKDIR/restore)

Usage

WORKDIR=/path/to/your/workdir IMAGE=`image` ./run-backup.sh -t FULL|DIFF|INCR

🔍 Discover Image Metadata

Learn what's inside the dar-backup image: program versions, build metadata, and available versions.

🧪 1. Check Tool Versions

Run the image with different entrypoints to check the bundled versions of dar-backup, dar, and par2:

IMAGE=per2jensen/dar-backup:0.5.1

# dar-backup version
docker run --rm --entrypoint "dar-backup" "$IMAGE" -v

# dar version
docker run --rm --entrypoint dar "$IMAGE" --version

# par2 version
docker run --rm --entrypoint par2 "$IMAGE" --version

# Or get them all in one go:
docker run --rm --entrypoint "" "$IMAGE" \
  bash -c "dar-backup -v; dar --version; par2 --version"

🏷️ 2. Inspect Image Labels

docker pull per2jensen/dar-backup:0.5.1
docker inspect per2jensen/dar-backup:0.5.1 | jq '.[0].Config.Labels'

{
  "org.opencontainers.image.base.created": "2025-06-19T13:38:32Z",
  "org.opencontainers.image.created": "2025-06-19T13:38:32Z",
  "org.opencontainers.image.description": "Container for DAR-based backups using dar-backup",
  "org.opencontainers.image.ref.name": "ubuntu",
  "org.opencontainers.image.source": "https://hub.docker.com/r/per2jensen/dar-backup",
  "org.opencontainers.image.version": "0.5.1"
}

📦 3. List Available Image Tags

# Show first 100 available tags
curl -s 'https://hub.docker.com/v2/repositories/per2jensen/dar-backup/tags?page_size=100' \
  | jq -r '.results[].name' | sort -V

Image deep diving

Although dar-backup is the primary CLI inside the container, you can also run dar directly from the image to take manual backups or inspect archives — perfect for advanced workflows or testing.

Here's a minimal example of how to use dar directly:

export DATA_DIR=/tmp/test-data
export BACKUP_DIR=tmp/test-backups
export IMAGE=per2jensen/dar-backup:0.5.6
touch /tmp/test-data/TEST.txt

docker run --rm -v "$DATA_DIR":/data -v "$BACKUP_DIR":/backup --entrypoint dar "$IMAGE" -c /backup/myarchive -R /data

Example output

No terminal found for user interaction. All questions will be assumed a negative answer (less destructive choice), which most of the time will abort the program.

 --------------------------------------------
 1 inode(s) saved
   including 0 hard link(s) treated
 0 inode(s) changed at the moment of the backup and could not be saved properly
 0 byte(s) have been wasted in the archive to resave changing files
 0 inode(s) with only metadata changed
 0 inode(s) not saved (no inode/file change)
 0 inode(s) failed to be saved (filesystem error)
 0 inode(s) ignored (excluded by filters)
 0 inode(s) recorded as deleted from reference backup
 --------------------------------------------
 Total number of inode(s) considered: 1
 --------------------------------------------
 EA saved for 0 inode(s)
 FSA saved for 1 inode(s)
 --------------------------------------------

This shows that even without dar-backup, you can still invoke dar manually — helpful for debugging, recovery scenarios, or power-user workflows.

🧠 Tip: You can also run par2 directly using --entrypoint par2 if needed.

Common dar-backup commands

Full backup

dar-backup --full-backup

Diff backup (requires prior FULL)

dar-backup --differential-backup

Incremental backup (requires DIFF)

dar-backup --incremental-backup

List available archives

dar-backup --list

List contents of a backup

dar-backup --list-contents <archive_name>

Restore

dar-backup --restore <archive_name>

Release procedure

Check version numbers and more

make FINAL_VERSION=0.5.2  DAR_BACKUP_VERSION=0.8.0 final-dryrun 
🔎 FINAL DRY-RUN
   FINAL_VERSION       = 0.5.2
   DAR_BACKUP_VERSION  = 0.8.0
   UBUNTU_VERSION      = 24.04
   BASE_IMAGE_NAME     = dar-backup-base
   FINAL_IMAGE_NAME    = dar-backup
   DOCKERHUB_REPO      = per2jensen/dar-backup

🔨 Image tags:
   - dar-backup:0.5.2
   - per2jensen/dar-backup:0.5.2

📦 Labels (subset):
   org.opencontainers.image.version       = 0.5.2
   org.dar-backup.version                 = 0.8.0
   org.opencontainers.image.revision      = 5cca8a9
   org.opencontainers.image.created       = 2025-07-13T14:06:57Z

✅ Dry-run done. Run 'make final' to build.

Build final

make FINAL_VERSION=0.5.2 DAR_BACKUP_VERSION=0.8.0 final
...
🔎 Verifying 'dar-backup --version' matches DAR_BACKUP_VERSION (0.8.0 )
✅ dar-backup --version is correct: 0.8.0
make[1]: Leaving directory '/home/pj/git/dar-backup-image'
make[1]: Entering directory '/home/pj/git/dar-backup-image'
🔍 Verifying OCI image labels on dar-backup:0.5.2
✅ org.opencontainers.image.authors: Per Jensen <dar-backup@pm.me>
✅ org.opencontainers.image.base.name: ubuntu
✅ org.opencontainers.image.base.version: 24.04
✅ org.opencontainers.image.created: 2025-07-13T14:09:02Z
✅ org.opencontainers.image.description: Container for DAR-based backups using 
✅ org.opencontainers.image.licenses: GPL-3.0-or-later
✅ org.opencontainers.image.ref.name: per2jensen/dar-backup:0.5.2
✅ org.opencontainers.image.revision: 5cca8a9
✅ org.opencontainers.image.source: https://github.com/per2jensen/dar-backup-image
✅ org.opencontainers.image.title: dar-backup
✅ org.opencontainers.image.url: https://hub.docker.com/r/per2jensen/dar-backup
✅ org.opencontainers.image.version: 0.5.2
🎉 All required OCI labels are present.
make[1]: Leaving directory '/home/pj/git/dar-backup-image'

Do a dry-run release

This builds the image and runs the test cases against it.

make FINAL_VERSION=0.5.6 DAR_BACKUP_VERSION=0.8.0 dry-run-release
...
2025-07-13 14:12:13,182 - INFO - Type of backup:   INCR
2025-07-13 14:12:13,183 - INFO - ======================================
2025-07-13 14:12:13,184 - INFO - ===> Starting INCR backup for /backup.d/default
[14:12:13] [~] Not a terminal — progress bar skipped.        rich_progress.py:62
2025-07-13 14:12:13,219 - INFO - INCR backup completed successfully.
2025-07-13 14:12:13,435 - INFO - Catalog for archive '/backups/default_INCR_2025-07-13' added successfully to its manager.
2025-07-13 14:12:13,436 - INFO - Starting verification...
[14:12:13] [~] Not a terminal — progress bar skipped.        rich_progress.py:62
2025-07-13 14:12:13,504 - INFO - Archive integrity test passed.
2025-07-13 14:12:13,569 - INFO - No files between 1MB and 20MB for verification, skipping
2025-07-13 14:12:13,569 - INFO - Verification completed successfully.
2025-07-13 14:12:13,569 - INFO - Generate par2 redundancy files.
2025-07-13 14:12:13,570 - INFO - 1/1: Now generating par2 files for /backups/default_INCR_2025-07-13.1.dar
2025-07-13 14:12:13,603 - INFO - 1/1: Done
2025-07-13 14:12:13,603 - INFO - par2 files completed successfully.
2025-07-13 14:12:13,603 - INFO - END TIME: 1752415933
✔ INCR backup (requires DIFF first)
make[1]: Leaving directory '/home/pj/git/dar-backup-image/.dryrun'
✅ Dry-run complete — no changes made to working directory
...

Do a Release

Set DOCKER_USER and DOCKER_TOKEN envvars first.

make FINAL_VERSION=0.5.6 DAR_BACKUP_VERSION=0.8.0 release
...
🔁 Skipping verify-cli-version (will be run by release)
🔍 Verifying OCI image labels on dar-backup:0.5.6
✅ org.opencontainers.image.authors: Per Jensen <dar-backup@pm.me>
✅ org.opencontainers.image.base.name: ubuntu
✅ org.opencontainers.image.base.version: 24.04
✅ org.opencontainers.image.created: 2025-07-13T17:08:24Z
✅ org.opencontainers.image.description: Container for DAR-based backups using 
✅ org.opencontainers.image.licenses: GPL-3.0-or-later
✅ org.opencontainers.image.ref.name: per2jensen/dar-backup:0.5.6
✅ org.opencontainers.image.revision: b583e85
✅ org.opencontainers.image.source: https://github.com/per2jensen/dar-backup-image
✅ org.opencontainers.image.title: dar-backup
✅ org.opencontainers.image.url: https://hub.docker.com/r/per2jensen/dar-backup
✅ org.opencontainers.image.version: 0.5.6
🎉 All required OCI labels are present.
🔎 Verifying 'dar-backup --version' matches DAR_BACKUP_VERSION (0.8.0 )
✅ dar-backup --version is correct: 0.8.0
🔐 Logging in to Docker Hub (2FA enabled)...
echo "$DOCKER_TOKEN" | docker login -u "$DOCKER_USER" --password-stdin
Login Succeeded
🚀 Pushing image per2jensen/dar-backup:0.5.6
The push refers to repository [docker.io/per2jensen/dar-backup]
5f70bf18a086: Layer already exists 
dab3496ba942: Layer already exists 
6dbcafa4e191: Layer already exists 
50838a8b9a7e: Pushed 
db49808a00f3: Pushed 
0dde0d1808a7: Pushed 
76550f3c9c5b: Pushed 
45a01f98e78c: Layer already exists 
0.5.6: digest: sha256:ef94dae75ecc698f4e81d49020fcf1c3d0490d3c257f97c3dd33c974d6e1c496 size: 2812
✅ Log entry added. Total builds: 4
{
  "build_number": 3,
  "tag": "0.5.6",
  "dar_backup_version": "0.8.0",
  "base_image": "dar-backup-base:24.04-0.5.6",
  "full_image_tag": "per2jensen/dar-backup:0.5.6",
  "git_revision": "b583e85",
  "created": "2025-07-13T17:08:57Z",
  "dockerhub_tag_url": "https://hub.docker.com/r/per2jensen/dar-backup/tags/0.5.6",
  "digest": "sha256:ef94dae75ecc698f4e81d49020fcf1c3d0490d3c257f97c3dd33c974d6e1c496",
  "image_id": "sha256:3494bd51f42da13d11f6528e1c2c51f6b1094eb66a01e9af4ba98c0674f21ffd"
}
🔄 Checking if doc/build-history.json changed
[main 93b01da] build-history: add 0.5.6 metadata
 1 file changed, 35 insertions(+)
✅ doc/build-history.json updated and committed
✅ Release complete for: per2jensen/dar-backup:0.5.6

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Containerized dar-backup: run automated, verifiable dar backups in Docker, Kubernetes, or on your local machine.

Topics

kubernetes backup archive disaster-recovery par2 dar long-term-storage

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