Barman

When an instance is given the barman role in config.yml, TPA will configure it as a Barman server to take backups of any other instances that name it in their backup setting.

instances:

- Name: one
  backup: two
  …


- Name: two
  role:
  - barman
  …

Multiple postgres instances can have the same Barman server named as their backup ; equally, one postgres instance can have a list of Barman servers named as its backup and backups will be taken to all of the named servers.

The default Barman configuration will connect to PostgreSQL using pg_receivewal to take continuous backups of WAL, and will take a full backup of the instance using rsync over ssh twice weekly. Full backups and WAL are retained for long enough to enable recovery to any point in the last 4 weeks.

Barman configuration

On each barman server, a global configuration file will be created as /etc/barman.conf ; this contains default values for many barman configuration variables. For each postgres server being backed up, an additional Barman configuration file is created: to back up the server one , the file will be /etc/barman.d/one.conf , and the backups will be stored in /var/lib/barman/one . The file and directory names are taken from the backed-up instance’s backup_name setting, defaulting to the instance’s name.

The following variables can be set on the backed-up instance and are passed through into Barman’s configuration with the prefix barman_ removed:

variable	default
barman_archiver	false
barman_log_file	/var/log/barman.log
barman_backup_method	rsync
barman_compression	pigz
barman_reuse_backup	link
barman_parallel_jobs	1
barman_backup_options	concurrent_backup
barman_immediate_checkpoint	false
barman_network_compression	false
barman_basebackup_retry_times	3
barman_basebackup_retry_sleep	30
barman_minimum_redundancy	3
barman_retention_policy	RECOVERY WINDOW OF 4 WEEKS
barman_last_backup_maximum_age	1 WEEK
barman_pre_archive_retry_script
barman_post_backup_retry_script
barman_post_backup_script
barman_streaming_wals_directory

Backup scheduling

TPA installs a cron job in /etc/cron.d/barman which will run every minute and invoke barman cron to perform maintenance tasks.

For each instance being backed up, it installs another cron job in /etc/cron.d/<backup_name> which takes the backups of that instance. This job runs as determined by the barman_backup_interval variable for the instance, with the default being to take backups at 04:00 every Wednesday and Saturday.

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