Replication check should fail if master and slave are the same.

Master and slave are required parameters.

Author: phumpal

CHANGELOG.md

@@ -4,6 +4,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 This CHANGELOG follows the format listed [here](https://github.com/sensu-plugins/community/blob/master/HOW_WE_CHANGELOG.md).
 
 ## [Unreleased]
+- check-postgres-replication.rb - critical if slave is undefined, localhost or master and slave are same
 
 ### Fixed
 - check-postgres-replication.rb: fix condition where connection timeout is considered a boolean rather than an integer value (@majormoses) (@phumpal) (@VeselaHouba)

bin/check-postgres-replication.rb

@@ -43,13 +43,14 @@ class CheckPostgresReplicationStatus < Sensu::Plugin::Check::CLI
   option(:master_host,
          short: '-m',
          long: '--master-host=HOST',
+         required: true,
          description: 'PostgreSQL master HOST')
 
   option(:slave_host,
          short: '-s',
          long: '--slave-host=HOST',
-         description: 'PostgreSQL slave HOST',
-         default: 'localhost')
+         required: true,
+         description: 'PostgreSQL slave HOST')
 
   option(:port,
          short: '-P',
@@ -106,6 +107,8 @@ class CheckPostgresReplicationStatus < Sensu::Plugin::Check::CLI
   def run
     ssl_mode = config[:ssl] ? 'require' : 'prefer'
 
+    critical 'Master and slave cannot be the same host' if config[:master_host] == config[:slave_host]
+
     # Establishing connection to the master
     pgpass
     conn_master = PG.connect(host: config[:master_host],