PostgreSQL 12 High Availability Cookbook - Third Edition

How to do it...

For the purposes of this recipe, pgha1 will remain our primary node and the witness will be pgha3. As always, the /db/pgdata path will be our default data directory.

All of these commands should be executed from pgha3. Follow these steps to produce a fully functional repmgr witness:

1. Create a new and empty PostgreSQL instance using initdb as the postgres user:

initdb -D /db/pgdata

2. Modify the postgresql.conf file and set the following parameter:

shared_preload_libraries = 'repmgr' 

3. Modify the pg_hba.conf file and add the following line:

host     all     repmgr     10.0.30.0/24     trust 

4. Start the PostgreSQL service with this command on Debian-based systems:

sudo systemctl start postgresql@12-main

Red Hat derivatives should restart ...