mwaeckerlin/pull-backup repository overview

⁠Docker Image that Pulls Backups from a Remote Host

Configuration is through two environment variables:

• REMOTE declares the remote site that has to be backed up in the form user@host:/path/to/origin/
• TIME backup time in cron format, defaults to 0 3 * * * (nightly at three o'clock)
• SLEEP time in seconds before the initial backup starts (60s)
• RSYNC_OPTIONS options passed to rsync, defaults to -aq --delete-before see man rsync for details
• KEYSIZE ssh rsa key size, defaults to 4096

The volumes are:

• /backup the backup target
• /root contains the file log with backup results and the directory .ssh with ssh keys

Please note, that your local network's DNS might not be available in the docker container, so use IP addresse in that case.

When you start the docker container, it outputs the public ssh key to the docker logs. You need to append this to the remote user's ~/.ssh/authorized_keys file.

The key line looks somehow like this:

ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAAAgQCvwSsm0Qw8PSupDh+/pSp0lo339UuHizLC/+XPNv7IvI2yc732XPO5wFQKMUz1p+dCm5XHXcGJArn5gm+gEKQD+97LM53Y2aEsL2J39oKLxoc5V4me82vgb0p0j4+Qq7iMjaKa8z5kOUvG4zxBM1It/wdvxM35zq65J48Q3L4vdw== root@850fe0680855

When you start the container, it starts with an initial backup after one minute. Use that time to copy the public key to the user's ~/.ssh/authorized_keys in the origin's host. If you need more time, set the environment variable SLEEP (in seconds).

Example:

Backup the data below path /var/something on host 192.168.0.99 and access it with user account myname. It is more secure, if user myname has only read access to /var/something and cannot access other paths on 192.168.0.99. The backup is copied to the host where docker runs, there it is stored in path /var/something-copy.

You can either specify REMOTE with one or more remote addresses tobackup, such as -e [email protected]:/var/something [email protected]:/var/lib/other, or you can seperate the definitions in: -e REMOTE_USER=myname, -e REMOTE_HOST=192.168.99 and -e REMOTE_PATH=/var/something /var/lib/other. Please note, that for rsync, the trailing slash in a path has a meaning.

Start the backup process on the target computer:

docker run -d --name pull-backup-something \
           -v /var/something-copy:/backup \
           -e SLEEP=30 \
           -e RSYNC_OPTIONS="-av --delete-before" \
           -e [email protected]:/var/something/ \
           mwaeckerlin/pull-backup

Get the key

docker logs -f pull-backup-something

Copy the key to path ~myname/.ssh/authorized_keys on host 192.168.0.99 within the thirty seconds before the initial backup starts.

See what actually happens in the backup log:

docker logs -f pull-backup-something

Afert a while (see logs), local path /var/something-copy contains a backup of /var/something on host 192.168.0.99.

That's all. The synchronization is repeated each day a 3 o'clock (UTC) in the morning.

The same command can be started on several computers to have more than one backup if your data is importand.

⁠Backup from remote Docker

It can easily be used in conjunciton with mwaeckerlin/ssh, e.g. to backup the subversion volume:

First, on the backup target machine, start a pull-backup container, e.g.:

docker run -d --name svn-backup-volume mwaeckerlin/pull-backup sleep infinity
docker run -d --name svn-backup-pull \
           --volumes-from svn-backup-volume \
           -e REMOTE="root@host:/svn" \
           -e PORT="200" \
           mwaeckerlin/pull-backup \
&& docker logs -f svn-backup-pull

When you see the key, copy it and enter it, when you start the ssh server on the backup source machine, e.g,:

docker run -d --name svn-backup-provider \
           -p 200:22 --volumes-from svn-volume \
           -e SSHKEY="ssh-rsa AAAAADAQAB…bL4jsnRWr5p2Q== root@f76c20a0e0cf" \
           mwaeckerlin/ssh