1. Prepare the Backup Server and Database Server

To begin, you’ll need to install the following packages on Debian-based installations:

• For the Barman Backup Server:

  python3-barman-latest_version barman_3-latest_version barman-cli_3-latest_version

• For the PostgreSQL Server:

  python3-barman-latest_version barman-cli_3-latest_version`

Once the installation is complete on both nodes, configure SSH access between the servers using the barman (on the backup server) and postgres (on the PostgreSQL server) user accounts.

Additionally, you’ll need to create the necessary users on PostgreSQL and configure it to archive data to the Barman backup server.

Note: Barman requires backups to be executed from the master node, not from a slave.

2. Configure PostgreSQL Server

Run the following commands to create users with appropriate privileges:

CREATE USER barman WITH SUPERUSER LOGIN PASSWORD 'super_password';

CREATE USER streaming_barman WITH REPLICATION PASSWORD 'super_password_repl';

If necessary, generate SSH keys for the postgres user using the following command:

ssh-keygen

Make the following changes in your postgresql.conf file to enable archiving:

archive_mode = on		# enables archiving; off, on, or always
				# (change requires restart)

archive_command = 'barman-wal-archive BARMAN_BACKUP_SERVERIP postgres_master_hostname %p'		# command to use to archive a WAL file
				# placeholders: %p = path of file to archive

Remember: Enabling archive_mode = on requires a restart of PostgreSQL.

Alternatively, you can change archive_command via psql:

ALTER SYSTEM SET archive_command = 'barman-wal-archive BARMAN_BACKUP_SERVERIP postgres_master_hostname %p';

Then, modify your pg_hba.conf file to add the Barman server IP address and users:

host    postgres        barman          BARMAN_BACKUP_SERVERIP/32      
   scram-sha-256

host    replication     streaming_barman    BARMAN_BACKUP_SERVERIP/32  
    scram-sha-256

Lastly, reload the PostgreSQL configuration:

SELECT pg_reload_conf();

Now, your PostgreSQL server is ready!

3. Configure Barman Backup Server

The main Barman configuration file is located at /etc/barman.conf. Edit it as follows to suit your setup:

barman_user = barman
configuration_files_directory = /etc/barman.d
barman_home = /path/to/barman_home/
log_file = /path/to/barman_home/log/barman.log
log_level = INFO 
 
immediate_checkpoint = false 
basebackup_retry_times = 3
minimum_redundancy = 3 
retention_policy = RECOVERY WINDOW OF 4 WEEKS

Next, create a configuration file for the PostgreSQL master in /etc/barman.d/postgres_master_hostname.conf:

[postgres_master_hostname]
description = "postgres_master_hostname backup PostgreSQL Database"
conninfo = host=postgres_master_IP user=barman dbname=postgres
streaming_conninfo = host=postgres_master_IP user=streaming_barman
backup_method = postgres
streaming_archiver = on
slot_name = barman
create_slot = auto
archiver = on

Next, create a .pgpass file in /var/lib/barman/ to store the credentials:

postgres_master_IP:5432:postgres:barman:super_password
postgres_master_IP:5432:replication:streaming_barman:super_password_repl

4. Verify Configuration

To ensure everything is configured correctly, run the following check:

barman check postgres_master_hostname

Example output:

barman@pod-bcp:~$ barman check postgres_master_hostname

Server target_node_db1:
PostgreSQL: OK
superuser or standard user with backup privileges: OK
PostgreSQL streaming: OK
wal_level: OK
replication slot: FAILED (replication slot 'barman' doesn't exist. Please execute 'barman receive-wal --create-slot postgres_master_hostname')
directories: OK
retention policy settings: OK
backup maximum age: OK (no last_backup_maximum_age provided)
backup minimum size: OK (660.5 MiB)
wal maximum age: OK (no last_wal_maximum_age provided)
wal size: OK (1.0 GiB)
compression settings: OK
failed backups: OK (there are 0 failed backups)
minimum redundancy requirements: OK (have 3 backups, expected at least 3)
pg_basebackup: OK
pg_basebackup compatible: OK
pg_basebackup supports tablespaces mapping: OK
systemid coherence: OK (no system Id stored on disk)
pg_receivexlog: OK
pg_receivexlog compatible: OK
receive-wal running: FAILED (See the Barman log file for more details)
archive_mode: OK
archive_command: OK
continuous archiving: OK
archiver errors: OK

If you see a failed replication slot, you will need to create the replication slot:

barman receive-wal --create-slot postgres_master_hostname

Afterward, rerun the check command:

barman check postgres_master_hostname

If the status is OK, you are ready to start backups!

If you see the error: WAL archive: FAILED (please make sure WAL shipping is setup), force a WAL switch:

barman switch-wal --force --archive postgres_master_hostname

Then rerun the check.

5. Run Your First Backup

Once everything is set up, you can initiate your first backup with:

barman backup postgres_master_hostname

To list all backups, use:

barman list-backups all

To check the status of a specific backup, run:

barman status postgres_master_hostname

6. Set Up a Backup Cron Job

To schedule regular backups, add a cron job. For example, to run a full backup every day at 1:30 AM:

30 01 * * * /usr/bin/barman backup postgres_master_hostname

Important Notes

WARNING

The following configuration files are not saved during the backup process and need to be manually restored:

• postgresql.conf
• pg_hba.conf

These files should be manually restored after recovering the PostgreSQL instance.

That’s it! You now have a fully configured and automated backup system using Barman for PostgreSQL.

Last modified on 2025-03-03