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. /etc/systemd/system/service_name.service:
systemctl status *service_name* - See the status of an applicationsystemctl start/stop *service_name* - Start or stop an applicationsystemctl restart *service_name* - Restart an applicationsystemctl enable/disable *service_name* - Enable or disable automatic start when server startssystemctl 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.