This needs to be carried out on the primary node. Note that the commands executed are different in the primary node than the secondary.

1. Configure the REPMGR configuration file (default located on “/etc/repmgr/10/repmgr.conf”) by changing the configuration as follows:
   (Remove comments # in the file)

   node_id = 1 node_name = 'N1' conninfo = 'host=<LOCAL IP> port=5432 user=repuser dbname=postgres password=<POSTGRES USER PASSWORD>' replication_type = 'physical' use_replication_slots = yes pg_bindir = '/usr/pgsql-10/bin' failover = 'automatic'  data_directory = '/var/lib/pgsql/10/data' promote_command = '/usr/pgsql-10/bin/repmgr standby promote -f /etc/repmgr/10/repmgr.conf --log-to-file' follow_command = '/usr/pgsql-10/bin/repmgr standby follow -f /etc/repmgr/10/repmgr.conf --log-to-file --upstream-node-id=%n' monitoring_history = yes monitor_interval_secs = 10 service_start_command = 'sudo systemctl start postgresql-10' service_stop_command = 'sudo systemctl stop postgresql-10' service_restart_command = 'sudo systemctl restart postgresql-10' service_reload_command = 'sudo systemctl reload postgresql-10'

   Note that you can find the the configuration parameters description here:
   https://raw.githubusercontent.com/2ndQuadrant/repmgr/master/repmgr.conf.sample

2. After changing the above configurations, the linux postgres user needs to initialize the primary node.
   1. su - postgres
   2. /usr/pgsql-10/bin/repmgr -f /etc/repmgr/10/repmgr.conf primary register
   3. Make sure that the primary was registered by running the following command:
      /usr/pgsql-10/bin/repmgr -f /etc/repmgr/10/repmgr.conf cluster show