Docker image to do scheduled backups of PostgreSQL DBs

This Dockerfile can be used to do daily backups and cleanup archive with a policy like this:

• Do backups every X hours
• Keep at least one backup for each of X last days (last backup for all previous days)
• Keep at least one backup for each of X last weeks (e.g. for each Monday of last 2 weeks)
• Keep at least one backup for each of X last months (e.g. for each 3d day of any last 5 month)

You can have as many connections to backup as you want (maximum number is 99 though) and for each of it you need to have a config like this:

• BACKUP_NAME_[1..99] - Name which will be used to generate backup files.
• SCHEDULE_[1..99] - Cron format for running backups (e.g. 23 */3 * * *). Default: 0 0 * * *
• BACKUP_DIR_[1..99] - Directory to keep backups. Default: /data
• BACKUP_DB_HOST_[1..99] - DB host to backup. Default: localhost
• BACKUP_DB_PORT_[1..99] - DB port to backup. Default: 5432
• BACKUP_DB_NAME_[1..99] - DB name to backup. Default: template1
• BACKUP_DB_USER_[1..99] - DB use to backup. Default: postgres
• BACKUP_DB_PASSWORD_[1..99] - DB use to backup. Default: `` (empty string)
• BACKUP_OPTIONS_[1..99] - options pg_dump utility. Default: `` (empty string)
• SAFE_DAYS_[1..99] - Number of days when we keep one backup per each day. Default: 7
• SAFE_WEEKS_[1..99] - Number of weeks when we keep backup per each week. Default: 4
• SAFE_WEEK_DAY_[1..99] - Name of the Day of the Week to keep backup. Valid values: Monday,Tuesday, Wednesday,Thursday,Friday,Saturday,Sunday Default: Monday
• SAFE_MONTHS_[1..99] - Number of months when we keep one backup per each month. Default: 6
• SAFE_MONTH_DATE_[1..99] - Date of any month to keep backup. Valid values: 1-28. Default: 1

In fact Docker container will have cron which will run pg_backup and proceed cleanup of old backups accordingly configs for each of provided connections.