borgmatic Container

Description

This repository provides a Docker image for borgmatic, a simple and efficient backup tool based on Borgbackup. The image is designed to make it easy to set up and run borgmatic (with Borg and optionally Cron daemon) within a Docker container, enabling you to streamline your backup process and ensure the safety of your data.

Usage

Prerequisites

Before proceeding, ensure that you have Docker installed and properly configured on your system. Refer to the Docker documentation for installation instructions specific to your operating system. If you want to use docker-compose, you may also need to install it seperately. Alternatively, you can also use podman to run this image.

Getting Started

Run this command to create data directories required by this image under your prefered directory.

mkdir data/{borgmatic.d,repository,.config,.ssh,.cache}

Configure a copy of borgmatic's config.yaml in data/borgmatic.d and run the container. You can modify any of the host mount point to fit your backup configuration.

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

See Other usage methods below for more options.

Volumes

The following volumes are available for mounting:

To generate an example borgmatic configuration, run:

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

Environment

You can set the following environment variables:

You can also provide your own crontab file. If data/borgmatic.d/crontab.txt exists, BACKUP_CRON will be ignored in preference to it. 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

Beside that, you can also pass any environment variable that is supported by borgmatic. See documentation for borgmatic and Borg and for a list of supported variables.

Other usage methods

Run borgmatic like a binary through a container

This image can be used to run borgmatic like a binary by passing the borgmatic command while running the container. It allows you to isolate your system and execute borgmatic commands without directly installing borgmatic on your host system and only keeping persistent data.

To execute borgmatic commands, you can run your container by passing borgmatic subcommands:

docker run --rm -it \
MOUNT_FLAGS_HERE \
ghcr.io/borgmatic-collective/borgmatic \
list

NOTE Replace MOUNT_FLAGS_HERE placeholder with appropriate mount flags and optionally environment flags. See above for more clues.

This will execute borgmatic list in your container. The idea is to create symlink to a script which executes this. Now create a new file borgmatic-docker.sh somewhere like your workspace or home directory.

#!/bin/sh

docker run --rm -it \
MOUNT_FLAGS_HERE \
ghcr.io/borgmatic-collective/borgmatic \
"$@"

Modify the above script as per your needs and copy it's path. Now you can either create a symbolic link to this script or add it as alias.

1. Create a symlink to a directory that exists in your PATH variable e.g.:

chmod +x /path/to/script/borgmatic-docker.sh
sudo ln [-s] /path/to/script/borgmatic-docker.sh /usr/local/bin/borgmatic

2. Or, to create an alias add this to your ~/.bashrc or similar file for other shells.

alias borgmatic="sh /path/to/script/borgmatic-docker.sh"

Tip You can view list of available command line options in borgmatic's docs

Running as daemon

To keep the container always running for continous backup, you can run it in detached mode. If you do not pass the command, by default it'll start the cron daemon which will run borgmatic at interval set in crontab.txt file.

docker run -d --restart=always \
MOUNT_FLAGS_HERE \
ghcr.io/borgmatic-collective/borgmatic \

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

docker exec -it container_id_or_name bash

Then you can run borgmatic directly within that shell.

Structure deployment with docker-compose

Use docker compose for easily management of your borgmatic container. You can also use this image with your existing docker-compose configuration to immediate setup backups for your deployed containers and/or the host.

1. Copy .env.template to .env and edit it to your needs.

cp .env.template .env

You will need to configure environment variables for volumes. You can also directly configure docker-compose.yml file.

Beside these, you can also set other configuration variables in your .env file. See Environment section for more details.

2. Start the container

docker-compose up -d

3. To view logs

docker-compose logs -f

Miscelaneous

If you want to run borgmatic commands using this configuration instead of starting the container as daemon, you can run:

docker-compose run --rm borgmatic borgmatic list

If a container is already running, you can execute borgmatic commands in it by running:

docker-compose exec borgmatic ls
# or to run a shell
docker-compose exec borgmatic bash

Restoring backups

1. Stop the backup container: docker-compose down
2. Modify volume /host/mount/location in docker-compose.restore.yml file to point to the location where you want to restore your backup.
3. Run an interactive shell: docker-compose -f docker-compose.yml -f docker-compose.restore.yml run borgmatic
4. Fuse-mount the backup: borg mount /mnt/borg-repository <mount_point>
5. Restore your files
6. Finally unmount and exit: borg umount <mount_point> && exit.

Tip In case Borg fails to create/acquire a lock: borg break-lock /mnt/repository

Advanced

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."

Mount an archive as FUSE filesystem

While the parameters defined in above examples 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"

Additional Reading

Backup Docker using borgmatic - Thank you @modem7