Automatic Restart of Crashed Services with Systemd

On Linux distributions that use the systemd init system
(Debian 8, Debian 9, CentOS/RedHat 7, Ubuntu 16, and Ubuntu 18),
Plesk instructs systemd to restart certain services if they crash:

• Plesk services (sw-cp-server, sw-engine)
• Hosting services (PHP-FMP, nginx)
• Certain other services (Dovecot, MariaDB, and so on)

The systemd restart has the following settings, which you can customize
via panel.ini file:

• The respawn setting controls whether crashed services are restarted automatically.
  The setting is enabled by default. To turn it off, change the respawn setting value to off.

• The Service.RestartSec setting specifies the downtime in seconds
  after which systemd restarts a crashed service (5 seconds by default).

• The Service.Restart setting specifies under which conditions services must be restarted.
  The default value of the settings is on-failure. It means that a service will be restarted
  when it exits with a non-zero exit code.

  The Service.Restart setting accepts the following values:
  no|always|on-success|on-failure|on-abnormal|on-abort|on-watchdog.
  See the meaning of the values.

To customize the automatic restart of the crashed services with systemd:

1. Add the systemd settings that you want to change to the panel.ini file
   under the [systemd] section. For example:

   [systemd]
   Service.RestartSec = 7
   Service.Restart = always
   

2. For the customized settings to take effect, run the command of the following pattern:

   /usr/local/psa/admin/sbin/register_service --enable <service>
   

   where <service> is any service from this list.

   For example,

   /usr/local/psa/admin/sbin/register_service --enable sw-engine
   

Then the customized settings will be applied.