Use bind mounts instead of docker volumes. Then you just have normal directories to back up, the same as you would anything else.

Rsync works fine for most data. (I use borgbackup) For any database data, create a dump using pg_dump or mysqldump or whatever. Then backup the dump and all other volumes but exclude the db volume.

Besides using bind mounts(As @[email protected]) mentions, you can run a backup container, that mounts the volume, that you would like to create a backup for. The backup container would handle backing up the volume at regular interval.

This is what I do in thedocker-compose and k3s containers I backup. I can recommend autorestic as the container for backup, but there is a lot of options.

Bind mounts are easy to maintain and backup. However if you share data amongst multiple container docker volumes are recommend especially for managing state.

Backup volumes:

docker run --rm --volumes-from dbstore -v $(pwd):/backup containername tar cvf /backup/backup.tar /dbdata

• Launch a new container and mount the volume from the dbstore container
• Mount a local host directory as /backup
• Pass a command that tars the contents of the dbdata volume to a backup.tar file inside /backup directory.

docker docs - volumes

Database volume backup without stopping the service: bash into the container, dump it, and copy it out with docker cp. Run it periodically via crontab