fdrake/rsync-cron repository overview

⁠docker-rsync-cron

This is a fork of dkruger/docker-rsync-cron which adds the following features:

• The source and destination rsync directories can be configured
• Timezone is configurable
• SSH support for acting as either a remote source or remote destination

This is a cronjob docker container which is used to regularly sync two docker volumes using rsync.

This image is based off of dkruger/cron⁠ which provides a simple cron implementation. The cron daemon is used to execute rsync which will copy the contents of the rsync_src volume to the rsync_dst volume. The specific options are configurable via environment variables.

Checkout the example docker-compose.yml⁠ for an exmaple of setting up the container with named NFS volumes using Netshare.

⁠Using the image

The image is configurable via environment variables for configuring the rsync command settings:

• RSYNC_CRONTAB: The crontab time entry, defaults to nightly at midnight
• RSYNC_OPTIONS: Flags passed to rsync, defaults to -av --stats --timeout=3600
• RSYNC_UID: The UID to use when calling rsync, defaults to 0
• RSYNC_GID: The GID to use when calling rsync, defaults to 0
• RSYNC_SRC: The source directory used by rsync, defaults to /rsync_src
• RSYNC_DEST: The destination directory used by rsync, defaults to /rsync_dst
• TZ: The timezone used for the container as defined in the list of tz database time zones⁠, defaults to UTC

The image defines two volumes: /rsync_src, and /rsync_dst. The contents of /rsync_src will be copied to /rsync_dst on the interval defined by the crontab entry.

The rsync command is called using the format rsync /rsync_src/ /rsync_dst, so that the contents of /rsync_src will be copied no the directory itself.

Here is an example command for executing the container two rsync two NFS mounts using the Netshare volume plugin:

docker run \
    --name my-nfs-sync \
    --volume-driver=nfs \
    -v master-svr/volume1/master:/rsync_src \
    -v local-svr/export:/rsync_dst \
    -e RSYNC_OPTIONS="--archive --timeout=3600 --delete"
    dkruger/rsync-cron:latest

⁠SSH Example

This fork also spins up an SSH server, allowing for remote rsync connections. There is a small bit of additional configuration:

For both the client and server containers, mount a volume to /etc/ssh which will store the configuration file, along with the private and public keys for the SSH server. Upon start, it will auto-populate with the files.

For the server container, do the following:

• Expose port 22 from the container to any outside port number you wish.
• In the /etc/ssh/sshd_config, set the following:
  • PermitRootLogin yes
  • AuthorizedKeysfile /etc/ssh/authorized_keys
• Populate /etc/ssh/authorized keys with the public key that is in the client's /etc/ssh directory.

⁠Docker Compose Server Example

This runs rsync locally at 2am eastern time as well as persists a SSH server on port 15050 for a remote client.

version: "2"
services:
  image: fdrake/rsync-cron
  environment:
      RSYNC_OPTIONS: -av --stats --timeout=3600
      RSYNC_CRONTAB: 0 2 * * *
      RSYNC_DEST: /rsync_dst/local_server
      TZ: America/New_York
    volumes:
      - backup_etcssh:/etc/ssh
      - local_data_volume_i_want_backed_up:/rsync_src/local_data_volume_i_want_backed_up
      - archive_volume:/rsync_dst
    ports:
      - 15050:22
    restart: unless-stopped
volumes:
	backup_etcssh:
	  external: true
	local_data_volume_i_want_backed_up:
	  external: true
	archive_volume:
	  external: true

⁠Docker Compose Client Example

This connects to the server on 15050 and backs up the volumes local to this container over to the remote server's destination.

version: "2"
services:
  image: fdrake/rsync-cron
  environment:
    RSYNC_OPTIONS: -e "ssh -o StrictHostKeyChecking=no -i /etc/ssh/ssh_host_rsa_key -p 15050" -av --stats --timeout=3600
    RSYNC_CRONTAB: 30 0 * * *
    TZ: America/New_York
    RSYNC_DEST: root@server2:/rsync_dst/remote_server
  volumes:
    - client_backup_etcssh:/etc/ssh
    - data_i_want_backed_up:/rsync_src/data_i_want_backed_up
    - another_volume_i_want_backed_up:/rsync_src/another_volume_i_want_backed_up
  restart: unless-stopped
volumes:
  client_backup_etcssh:
    external: true
  data_i_want_backed_up:
    external: true
  another_volume_i_want_backed_up:
    external: true

⁠About permissions

Depending on your volume store, permissions might be an issue. For example some NAS implementations are very picky when it comes to the UID and GID of the process reading/writing. As such you may need to specify a UID and GID that has the correct permissions for the volumes. Note that these are the ID numbers, not the names.