add restart on failure

pmanager/pmanager.service

@@ -7,6 +7,8 @@ Requires=networking.service
 User=nginx
 Environment=SNOWMIX=/usr/local/lib/Snowmix-0.5.1
 ExecStart=/home/nginx/scripts-snowmix/pmanager/pmanager.py /home/nginx/scripts-snowmix/pmanager/server.json
+RestartSec=5
+Restart=on-failure
 
 [Install]
 WantedBy=multi-user.target