This is no beginner stuff! Every time I have to do a fresh install of Postgresql and make it work with Ruby on Rails. It is a pain in the ass. I made up my mind that this is going to be the last time I will have trouble doing this. So here we go with every minute details.

System Specification

  • Ubuntu 20.04
  • Postgres 12+

NOTE: This is the version of Ubuntu Linux I’m testing it with. Ubuntu is my primary OS. This should work on other Ubuntu versions without any change.

Installing Postgres

sudo apt-get install postgresql postgresql-contrib libpq-dev

Two ways to access Postgres from Rails

1. As the system user when no username and password is provided

# create a username with the same name as linux user with no password
sudo -u postgres psql
create role <linux_user_name> with createdb login password '';

2. Create a dedicated user for the application with password

# start Postgres interactive shell
sudo -i -u postgres psql
create role <app_name> with createdb login password '<app_name>';

Update the database.yml file with username and password in the default section or both test and development records

username: <app_name>
password: <app_name>


  1. How To Install and Use PostgreSQL on Ubuntu 18.04
  2. How To Set Up Ruby on Rails with Postgres
  3. PostgreSQL gem pg was unable to install