Systemd is a service that comes pre-installed with Ubuntu. Systemd can start and keep applications running on the server e.g. project moore, ordsys, nginx etc. Systemd can also start the applications automatically when the server starts.
To add an application to systemd, a service file needs to be added to
/etc/systemd/system. This done automatically by ansible for the roles that require it.
The commands listed below uses the argument service_name. This is the name of the service file in the systemd folder i.e.
systemctl status *service_name* - See the status of an application
systemctl start/stop *service_name* - Start or stop an application
systemctl restart *service_name* - Restart an application
systemctl enable/disable *service_name* - Enable or disable automatic start when server starts
systemctl daemon-reload - Reload systemd (usually needed if any of the service files has been changed)
Ubuntu also comes with the command
journalctl which can show logs for systemd services. You can view the logs of a service using
journalctl -u service_name.
Not all applications log messages in a way that can be viewed with
journalctl. Some directly to a file in
/var/log/ while some applications log to Sentry.