Borgmatic Container

Description

A little container I wrote to automate my Borgbackup's using the excellent Borgmatic. It uses cron to run the backups at a time you can configure in data/borgmatic.d/crontab.txt.

Warning As of 2022-01-29 this image has switched to use Supercronic instead of cron from alpine

Usage

To set your backup timing and configuration, you will need to create crontab.txt and your borgmatic config.yaml and mount these files into the /etc/borgmatic.d/ directory. When the container starts it creates the crontab from crontab.txt and starts crond. By cloning this repo in /opt/docker/, you will have a working setup to get started.

If using remote repositories mount your .ssh to /root/.ssh within the container.

Starting and stopping containers from hooks

In case you are using the container to backup docker volumes used by other containers, you might want to make sure that the data is consistent and doesn't change while the backup is running. The easiest way to ensure this is to stop the affected containers before the backup and restart them afterwards. You can use the appropriate borgmatic hooks and control the docker engine through the API using the hosts docker socket.

Please note that you might want to prefer the *_everything hooks to the *_backup hooks, as after_backup will not run if the backup fails for any reason (missing disk space, etc.) and therefore the containers stay stopped.

First mount the docker socket from the host by adding -v /var/run/docker.sock:/var/run/docker.sock to your run command or in the volume list of your docker-compose.yml.

Then use the following example to create the start/stop hooks in the config.yml for the containers that you want to control.

hooks:
    before_everything:
        - echo "Stopping containers..."
        - 'echo -ne "POST /v1.41/containers/<container1-name>/stop HTTP/1.1\r\nHost: localhost\r\n\r\n" | nc local:/var/run/docker.sock 80 > /dev/null && echo "Stopped Container 1" || echo "Failed to stop Container 1"'
        - 'echo -ne "POST /v1.41/containers/<container2-name>/stop HTTP/1.1\r\nHost: localhost\r\n\r\n" | nc local:/var/run/docker.sock 80 > /dev/null && echo "Stopped Container 2" || echo "Failed to stop Container 2"'
        - echo "Containers stopped."
        - echo "Starting a backup."

    after_everything:
        - echo "Finished a backup."
        - echo "Restarting containers..."
        - 'echo -ne "POST /v1.41/containers/<container1-name>/start HTTP/1.1\r\nHost: localhost\r\n\r\n" | nc local:/var/run/docker.sock 80 > /dev/null && echo "Started Container 1" || echo "Failed to start Container 1"'
        - 'echo -ne "POST /v1.41/containers/<container2-name>/start HTTP/1.1\r\nHost: localhost\r\n\r\n" | nc local:/var/run/docker.sock 80 > /dev/null && echo "Started Container 2" || echo "Failed to start Container 2"'
        - echo "Containers restarted."

Example run command

docker run \
  --detach --name borgmatic \
  -v /home:/mnt/source:ro \
  -v /opt/docker/docker-borgmatic/data/repository:/mnt/borg-repository \
  -v /opt/docker/docker-borgmatic/data/borgmatic.d:/etc/borgmatic.d/ \
  -v /opt/docker/docker-borgmatic/data/.config/borg:/root/.config/borg \
  -v /opt/docker/docker-borgmatic/data/.ssh:/root/.ssh \
  -v /opt/docker/docker-borgmatic/data/.cache/borg:/root/.cache/borg \
  -e TZ=Europe/Berlin \
  ghcr.io/borgmatic-collective/borgmatic

While the parameters above are sufficient for regular backups, following additional privileges will be needed to mount an archive as FUSE filesystem:

--cap-add SYS_ADMIN \
--device /dev/fuse \
--security-opt label:disable \
--security-opt apparmor:unconfined

Depending on your security system, --security-opt parameters may not be necessary. label:disable is needed for SELinux, while apparmor:unconfined is needed for AppArmor.

To init the repo with encryption, run:

docker exec borgmatic \
bash -c "borgmatic --init --encryption repokey-blake2"

Layout

/mnt/source

Your data you wish to backup. For some safety you may want to mount read-only. Borgmatic is running as root so all files can be backed up.

/mnt/borg-repository

Mount your borg backup repository here.

/etc/borgmatic.d

Where you need to create crontab.txt and your borgmatic config.yml

• To generate an example borgmatic configuration, run:

docker exec borgmatic \
bash -c "cd && generate-borgmatic-config -d /etc/borgmatic.d/config.yaml"

• crontab.txt example: In this file set the time you wish for your backups to take place default is 1am every day. In here you can add any other tasks you want ran

0 1 * * * PATH=$PATH:/usr/bin /usr/bin/borgmatic --stats -v 0 2>&1

/root/.borgmatic

Note this is now redundant and has been deprecated, please remove this from your configs

/root/.config/borg

Here the borg config and keys for keyfile encryption modes are stored. Make sure to backup your keyfiles! Also needed when encryption is set to none.

/root/.ssh

Mount either your own .ssh here or create a new one with ssh keys in for your remote repo locations.

/root/.cache/borg

A non-volatile place to store the borg chunk cache.

Environment

• Time zone, e.g. TZ="Europe/Berlin"'.
• SSH parameters, e.g. BORG_RSH="ssh -i /root/.ssh/id_ed25519 -p 50221"
• BORG_RSH="ssh -i /root/.ssh/id_ed25519 -p 50221"
• Repository passphrase, e.g. BORG_PASSPHRASE="DonNotMissToChangeYourPassphrase"

Docker Compose

• Prepare your configuration
  1. cp .env.template .env
  2. Set your environment and adapt volumes as needed
• To start the container for backup: docker-compose up -d
• For backup restore:
  1. Stop the backup container: docker-compose down
  2. Run an interactive shell: docker-compose -f docker-compose.yml -f docker-compose.restore.yml run borgmatic
  3. Fuse-mount the backup: borg mount /mnt/borg-repository <mount_point>
  4. Restore your files
  5. Finally unmount and exit: borg umount <mount_point> && exit.
• In case Borg fails to create/acquire a lock: borg break-lock /mnt/repository

Example interactive command

If you ever need to run borgmatic manually, for instance to view or recover files, run:

docker exec -it borgmatic bash

Then you can run borgmatic directly within that shell.

Additional Reading

Backup Docker using Borgmatic - Thank you @modem7