Docker containers backup

backup-docker-daily

#!/usr/bin/php
<?php
$local_backup_dir  = '/backup-local';
$target_backup_dir = '/backup';
$backup_prefix     = '';
$backup_suffix     = '-'.date('l');
/**
 * We'll make backups to local directory first and then move to target
 */
chdir($local_backup_dir);
/**
 * Remove old files if any
 */
exec('rm *');
/**
 * Get list of all containers, including stopped
 */
exec('docker ps -a', $docker_containers);
/**
 * Remove first line of the output
 */
array_shift($docker_containers);
foreach ($docker_containers as $container) {
	$container = explode(' ', $container);
	$container = array_pop($container);
	/**
	 * Do not backup containers created by docker-compose, as they are stateless
	 */
	if (preg_match('/.+_.+_[0-9]+$/', $container)) {
		continue;
	}
	/**
	 * Get more details about container
	 */
	unset($details);
	exec("docker inspect $container", $details);
	$details          = json_decode(implode('', $details), true)[0];
	$backup_file_name = $backup_prefix.$container.$backup_suffix;
	/**
	 * If this is nazarpc/webserver:data container - we need to backup data only using special container, otherwise use normal container export
	 */
	if ($details['Config']['Image'] === 'nazarpc/webserver:data') {
		exec("docker run --rm --volumes-from $container -v /$local_backup_dir:/backup --env BACKUP_FILENAME=$backup_file_name nazarpc/webserver:backup");
	} else {
		exec("docker export $container > $backup_file_name.tar");
	}
}
/**
 * Compress backups to decrease size
 */
exec("bzip2 -f *.tar");
/**
 * Move to target
 */
exec("mv -f *.tar.bz2 /$target_backup_dir");

I've saved this file as /etc/cron.daily/backup-docker-daily to have daily backups.