How to start the PostgreSQL cluster using sudo systemctl while running as postgres user that has no password?

Question

I am new to PostgreSQL world and I am facing this issue:

When I try to start postgres 14 cluster using the following command:

pg_ctlcluster 14 testcluster start

It starts but gives me the hint that:

Warning: the cluster will not be running as a systemd service. Consider using systemctl:
 sudo systemctl start postgresql@14-testcluster

And when I try the suggested command, it asks for unix user postgres password, which I have ever seen or set.

[sudo] password for postgres:

• Note 1: Ubuntu 22.04

• Note 2: I am running as postgres unix user using this command:

  sudo su - postgres
  

What can I do?

• mustaccio: If you can do sudo su - postgres (apparently as some other user), you can also do sudo systemctl start (as that same user).
• Ahmad: My main user is a sudoer, but appearantly postgres user is not. This error: postgres is not in the sudoers file. This incident will be reported. Also trying to run the cluster using the other sudoer user as sudo using this command: sudo systemctl start postgresql@14-testcluster failed: Job for [email protected] failed because the service did not take the steps required by its unit configuration. but when I try: sudo -u postgres systemctl start postgresql@14-testcluster it asks for my sudoer password, which I don't have because I only use keys
• mustaccio: As that same user (what you call "main").
• jjanes: "Job for [email protected] failed because the service did not take the steps required by its unit configuration" OK, so figure out why. Look in the log file.

Answer 1

You can either edit /etc/sudoers to allow user postgres to run that command without having to specify a password, or you start and stop PostgreSQL using a different operating system user that has the permission to run the command.