Backup docker volumes

docker_backup.py

#!/usr/bin/env python3
"""Backs up and restores data-only volumes to/from host backup directory using
rsync. Only backup named volumes, which is arbitrarily set to ones having a name
length < 40 characters.

1. Create a Docker image containing rsync (named rsync)

https://github.com/firecat53/dockerfiles/tree/master/rsync

``docker build -t rsync .``

2. Run ./docker_backup.py -h

"""
import argparse
import platform

import docker

BACKUP_DIR = "/var/backups/{}/docker".format(platform.node())

def parse_arguments():
    """Parse command line options.

    Returns: args

    """
    arg_parse = argparse.ArgumentParser(description="Backup or restore named Docker volumes")
    arg_parse.add_argument('mode', choices=['backup', 'restore'],
                           help="Choose backup or restore")
    arg_parse.add_argument('volumes', nargs='*', default=[],
                           help="Zero or more volumes to backup or restore. "
                           "Default is all available (< 40 char name) for "
                           "backup and none for restore")
    arg_parse.add_argument('--force', '-f', action='store_true', default=False,
                           help="Overwrite existing volume contents on "
                           "restore.")
    arg_parse.add_argument('--exclude', nargs='*', default=[],
                           help="List of directories to exclude from backup")
    return arg_parse.parse_args()


def run():
    """Main script entrypoint

    """
    args = parse_arguments()
    client = docker.DockerClient()
    try:
        client.images.get("rsync")
    except docker.errors.ImageNotFound:
        print("Rsync image not found. Build it and try again")
        return
    vols = client.volumes.list()
    vols = [i for i in vols if len(i.name) < 40]
    if args.exclude:
        exclude = '--exclude "' + '" --exclude "'.join(args.exclude) + '"'
    else:
        exclude = ""
    if args.mode == 'backup':
        vols = [i for i in vols if i.name in args.volumes] \
                if args.volumes else vols
        cmd = "rsync -aAXq --delete {} /mnt/ /backup/".format(exclude)
    if args.mode == 'restore':
        vols = [i for i in vols if i.name in args.volumes] \
                if args.volumes else []
        cmd = "rsync -aAXq --delete {} /backup/ /mnt/".format(exclude)
    if not vols:
        print("No containers backed up or restored")
        return
    for vol in vols:
        try:
            client.volumes.get(vol.name)
        except docker.errors.NotFound:
            print("{} does not exist.".format(vol.name))
            continue
        vol_back = {"{}/{}".format(BACKUP_DIR, vol.name):
                    {'bind': '/backup', 'mode': 'rw'},
                    vol.name: {'bind': '/mnt', 'mode': 'rw'}}
        client.containers.run(image='rsync',
                              remove=True,
                              command=cmd,
                              volumes=vol_back)


if __name__ == '__main__':
    run()