Postgresql socket configuration is undocumented, confusing

[melissaboiko]

Current install docs say:

• Set DB_HOST to the IP of the machine
• Set DB_PORT to the port on which your database server is exposed

Alternatively, if you are using a Unix socket:

• Set DB_SOCKET to the path of the socket, e.g. /run/mysqld/mysqld.sock

But this doesn't work for Postgresql. The only way I could make it work was:

DB_CONNECTION=pgsql
# DB_SOCKET=/run/postgresql/
DB_HOST=/run/postgresql/
DB_PASSWORD=null
DB_PORT=5432 # ?

DB_DATABASE=pixelfed
DB_USERNAME=pixelfed