Can not add Database Cluster to PostGreSQL plugin configuration. (4047912)

When attempting to add a Database Cluster to the PostGreSQL plugin a pop-up appears indicating that the plugin configuration is incorrect and suggests checking :

• Port
• Database SuperUser
• Password
• PostGreSQL Bin Directory
• PostGreSQL Data Directory
• Database Used for Initial Connection
• Template Database Used During Create Database

After confirming the configuration is correct by logging into PostGreSQL using the credentials configured for the PostGreSQL plugin, the database cluster can still not be added.

The PostGreSQL plugin is failing to connect to the database using the 'Ident' authentication method from 'localhost'.

Edit '/var/lib/pgsql/data/pg_hba.conf' and add the following two lines to allow login from localhost:

local all all trust
host all 127.0.0.1/32 trust

Note that the location of 'pg_hba.conf' may be different to that shown above.

A restart the PostGreSQL services may be required for the changes to take effect (i.e. with the following command):
service postgresql restart