Setup

The backup server

Server specs

• Ubuntu 16.04 (VM running on top of ESXi 6.5.0 build 5310538)
• 4 CPU
• 12G RAM
• 1000G HDD space

Server configuration

• Docker CE (version 17.09.0~ce-0~ubuntu)

• Docker Compose (version 1.16.1, build 6d1ac21)

• A dedicated user: moodle_backup (in the docker group)

• Passwordless SUDO to run rsync (we have found that running as the superuser on the receiver allows for better coping with users/groups/permissions)

  # /etc/sudoers.d/rsync
  moodleback ALL=(root) NOPASSWD: /usr/bin/rsync
  

• Jobs in cron (e.g. sudo crontab -u moodle_backup -e) that support 1) periodically pulling new Moodledata files and 2) checking to see whether a new database backup is ready to pull

  • Sync new Moodledata files every hour

    0 * * * * cd /path/to/sync/scripts/ && ./moodledata_sync_wrapper.sh
    

  • Check for a new database backup

    * * * * * cd /path/to/sync/scripts/ && flock --nonblock /tmp/signal.pid ./signal.sh
    

Moodledata

The backup server needs access to Moodle's file repository (Moodledata). In our setup, this is done via rsync/passwordless ssh to a server named content.midmich.edu (see moodledata_sync.sh for the command) with the (local) moodle_backup user on content.midmich.edu in the www-data group (Moodledata permissions are set to 0777, but having the user in www-data would support permissions of 0750).

Database

The backup server needs access to the database backup (see db3_database_backup.sh for one such example script). This is accomplished via rsync/passwordless ssh to a server named db3.midmich.edu (see database_sync.sh for the command) in our case that means adding the (local) moodle_backup user on db3.midmich.edu to the root group.

PHP Code

The backup server needs access to a container to run Moodle. This is accomplished through Gitlab's Docker container repository. The production Moodle container (approximated by Dockerfile_moodle_base) is used as a starting point for the backup node: essentially additional config is added to Moodle's config.php (see Dockerfile_moodle_backup for the syntax). Additionally, a new ENTRYPOINT script was written to automatically change some database settings when the Moodle container starts up.