Different authentication behaviour when starting postgres from pg_ctl and when starting from systemd

Question

I am running postgres 9.6 cluster on ubuntu 20.

All installation and starting the database is fine, however, I am experiencing a weird behavior.

In the pg_hba.conf file, I am trusting any connection from any user from the local host and it is working just fine when I start the cluster using the "pg_ctl start" utility.

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However, when I start it from the systemd, systemctl start [email protected], it fails with the following error

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Anyone has proper explanation for this difference in behaviour ?

Answer 1

Figured it why; When you use pg_ctl to stop/start your cluster, you define your data directory with -D argument.

However, when you start postgres with systemd 'systemctl stop/start <>', it fetch the configuration (postgresql.conf and pg_hba.conf) from /etc/postgresql/.... according to what is defined in the service definition in systemd.

That is what caused the difference in behaviour.

• Laurenz Albe: You should remove the configuration file that is wrong. That way, you will notice automatically if you try to start the server in the wrong way.