docker-rsync-cron

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 --archive --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

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

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.