7 steps after installing PostgresQL on Ubuntu Server 20.04

Problem:

After installation (sudo apt install postgresql-12) you try to connect to your fresh PostgresQL 12 using psql, but it's responding

psql: error: could not connect to server: FATAL:  Peer authentication failed for user "postgres"

Solution:

1) Make sure you've run pg_ctlcluster

sudo pg_ctlcluster 12 main start

2) Check postgres port and change it to 5432 if needed

sudo nano /etc/postgresql/12/main/postgresql.conf

in newer versions it might be 5433 by default, so it causes problems

find a string with port = 5433 and change it to port = 5432

3) Restart postgres service (just in case)

sudo service postgresql restart

4) Sign-in into psql using sudo

sudo -u postgres psql postgres

5) Set up postgres user's password. Don't forget the semicolon!

2 last steps on my DevOps blog