How to make a simple system.d service for a node.js server

Put this content:

[Unit]
Description={name}

[Service]
Type=simple
User={user}
ExecStart=/usr/bin/node {full-path-to-script}.js

[Install]
WantedBy=multi-user.target

... somewhere as {name}.service, where:

• {name} is the name of the service
• {user} is the name of the user to run the script (optional)

... then:

• run: this sudo ln -s /{full_path}/{name}.service /lib/systemd/system/{name}.service 
• then this: sudo systemctl daemon-reload
• then this: sudo systemctl enable {name}.service
• and finally this: sudo systemctl start {name}

How does it work?

• It starts the service on boot (see WantedBy section).
• Using ExecStart command. Important: we specify the full path to node
• SystemD remembers the PID of the new process and considers the service is ongoing until the process is died.
• So any subsequent systemctrl start {name} won't do anything if the previous process is alive.
• This behavior is determined by Type=Simple