Postgresql is not running. It's active but exited

Postgresql is not running.

Versions

PostgreSQL Version: 10.12
Distro: Linux Mint 19.3 (Tricia)/Ubuntu 18.04

Not working:

$ sudo service postgresql restart
$ sudo systemctl restart postgresql

systemctl status postgresql:

╭─root@danial /opt
╰─➤  systemctl status postgresql
● postgresql.service - PostgreSQL RDBMS
   Loaded: loaded (/lib/systemd/system/postgresql.service; enabled; vendor preset: enabled)
   Active: active (exited) since Mon 2020-07-13 22:52:54 +03; 9min ago
  Process: 22887 ExecStart=/bin/true (code=exited, status=0/SUCCESS)
 Main PID: 22887 (code=exited, status=0/SUCCESS)

Jul 13 22:52:54 17-V13-5 systemd[1]: Starting PostgreSQL RDBMS...
Jul 13 22:52:54 17-V13-5 systemd[1]: Started PostgreSQL RDBMS.

ss -nlp | grep postgre

u_str             LISTEN              0                    128                                                   /var/run/postgresql/.s.PGSQL.5432 188329                                                 * 0                                    users:(("postgres",pid=22869,fd=8))

tcp               LISTEN              0                    128                                                                           127.0.0.1:5432                                             0.0.0.0:*                                  

pg_lsclusters

Ver Cluster Port Status Owner    Data directory              Log file
10  main    5432 online postgres /var/lib/postgresql/10/main /var/log/postgresql/postgresql-10-main.log

ps ax | grep -i postgresq

 1495 ?        S      0:00 /usr/lib/postgresql/10/bin/postgres -D /var/lib/postgresql/10/main -c config_file=/etc/postgresql/10/main/postgresql.conf

systemctl status [email protected]

● [email protected] - PostgreSQL Cluster 10.12-main
   Loaded: loaded (/lib/systemd/system/[email protected]; indirect; vendor preset: enabled)
   Active: inactive (dead)
Condition: start condition failed at Wed 2020-07-15 07:20:02 +03; 51s ago

The postgresql.service systemd unit used as a top level grouping service, that does nothing than starting and sopping other services that depend on it.

As it implemented as service, it required to have a dummy ExecStart:

ExecStart=/bin/true
RemainAfterExit=on

You can examine that by running

systemctl cat postgresql.service

However (unfortunately), it's own status says nothing about services that depend on in. It just tells you that postgresql.service have been started and depending services requested to start.