How to change systemd service timeout value?

My systemd service kept timing out because of how long it would take to boot up also, so this fixed it for me:

1. Edit your systemd file:
   • For modern versions of systemd: Run systemctl edit --full node.service (replace "node" with your service name).
     • This will create a system file at /etc/systemd/system/node.service.d/ that will override the system file at /usr/lib/systemd/system/node.service. This is the proper way to configure your system files. More information about how to use systemctl edit is here.
   • Directly editing system file: The system file for me is at /usr/lib/systemd/system/node.service. Replace "node" with your application name. However, it is not safe to directly edit files in /usr/lib/systemd/ (See comments)

2. Use TimeoutStartSec, TimeoutStopSec or TimeoutSec (more info here) to specify how long the timeout should be for starting & stopping the process. Afterwards, this is how my systemd file looked:

   [Unit]
   Description=MyProject
   Documentation=man:node(1)
   After=rc-local.service
   
   [Service]
   WorkingDirectory=/home/myproject/GUIServer/Server/
   Environment="NODE_PATH=/usr/lib/node_modules"
   ExecStart=-/usr/bin/node Index.js
   Type=simple
   Restart=always
   KillMode=process
   TimeoutSec=900
   
   [Install]
   WantedBy=multi-user.target
   

   • You can also view the current Timeout status by running any of these (but you'll need to edit your service to make changes! See step 1). Confusingly, the associated properties have a "U" in their name for microseconds. See this Github issue for more information:
     • systemctl show node.service -p TimeoutStartUSec
     • systemctl show node.service -p TimeoutStopUSec
     • systemctl show node.service -p TimeoutUSec

3. Next you'll need to reload the systemd with systemctl reload node.service

4. Now try to start your service with systemctl start node.service
5. If that didn't work, try to reboot systemctl with systemctl reboot
6. If that didn't work, try using the --no-block option for systemctl like so: systemctl --no-block start node.service. This option is described here: "Do not synchronously wait for the requested operation to finish. If this is not specified, the job will be verified, enqueued and systemctl will wait until the unit's start-up is completed. By passing this argument, it is only verified and enqueued."
   • There is also the option to use systemctl mask instead of systemctl start. For more info see here.

Updates from Comments:

• TimeoutSec=infinity: Instead of using "infinity" here, put a large amount of time instead, like TimeoutSec=900 (15 min). If the application takes "forever" to exit, then it's possible that it will block a reboot indefinitely. Credit @Alexis Wilke and @JCCyC
• Instead of editing /usr/lib/systemd/system, try systemctl edit instead or edit /etc/systemd/system to override them instead. You should never edit service files in /usr/lib/. Credit @ryeager and @0xC0000022L

Running systemctl show SERVICE_NAME.service -p TimeoutStopUSec I could at least see the timeout set by systemd to my service.

I changed the script to a regular unit file one in order for it work properly.