Add systemd service file

opensprinkler_prometheus_exporter.service

+[Unit]
+Description=Opensprinkler prometheus exporter
+After=syslog.target network.target
+
+[Service]
+EnvironmentFile=-/etc/default/opensprinkler_prometheus_exporter
+ExecStart=/usr/local/src/opensprinkler_prometheus_exporter/opensprinkler_prometheus_exporter.py
+StartLimitInterval=5
+StartLimitBurst=10
+Restart=always
+RestartSec=120
+
+[Install]
+WantedBy=multi-user.target