With python we can also automate the barman backup and the zabbix monitoring as follows:

import os
import sys
sys.path.append('/opt/applications/management-tools/apps/nms-scripts/service/scripts/functions/')
sys.path.append('/opt/applications/management-tools/apps/nms-scripts/service/scripts/conf/')
import zabbixconfig
from zabbixconfig import zabbixmetric

def run_barmanbackup():
    try:
        print('Starting Backup')
        stream = os.popen('barman list-backup pgsql')
        failed_bkp_id = ""
        last_backup_id = ""
        failed_backups = 0
        total_backups = 0

        for line in stream.read().splitlines():
            if "FAILED" in line:
                failed_backups += 1
                failed_bkp_id = line.split(" ")[1]
                print('Found failed backup %s, will delete it.' % failed_bkp_id)
                delete_command = ('barman delete pgsql %s' % failed_bkp_id)
                os.system(delete_command)
            last_backup_id = line.split(" ")[1]
            total_backups += 1

        if total_backups - failed_backups >= 3:
            print('We have at least two healthy backups, will delete the last one: %s' % last_backup_id)
            delete_command = ('barman delete pgsql %s' % last_backup_id)
            os.system(delete_command)
        barman = os.popen('barman backup pgsql')
        output = barman.read()
        print(output)

        if output in 'ERROR':
            print("Failed running barman PostgreSQL backup")
            packet = zabbixmetric('bkp_status', "ERROR - FAILED running barman PostgreSQL backup")
        else:
            print("Backup run successfully")
            packet = zabbixmetric('bkp_status', "Backup completed successfully")
    except Exception as err:
        print(f'Failed running barman PostgreSQL backup : {err}')
        packet = zabbixmetric(f'bkp_status', 'ERROR - FAILED running barman PostgreSQL backup : {err}')

run_barmanbackup()

That script will keep 3 backups on the barman server.