Postgres normally allows access via socket for local users if a line of type "local" with method "trust" exists for a user/database pair in the pg_hba.conf file. However: The current default permissions of /run/postgresql - where the socket lives - do not allow any user to access the socket. Please change permission from drwxrwx--- 2 postgres postgres 80 21. Jun 13:12 /run/postgresql to drwxrwx--x 2 postgres postgres 80 21. Jun 13:12 /run/postgresql
The post-install message and the how-to document that the Linux user must be in the 'postgres' group. pg_hba.conf only defines rules for PostgreSQL roles. *** This bug has been marked as a duplicate of bug 395331 ***