Headless mode in Parallels Desktop Pro Edition

Question

I want to know more about the Headless mode in Parallels Desktop Pro Edition.

Information

Headless mode allows you to run virtual machines as background processes without the graphical user interface (GUI) displayed on the Mac desktop. Parallels Desktop runs as a background process (service) in this mode and is able to start a virtual machine automatically on the Mac startup. With this functionality, you can run multiple virtual machines on a single high-performance Mac providing virtual machine access to your users. The users can connect to their designated virtual machines via RDP, SSH, or other remote tools.

Note: Parallels Desktop 20 and newer versions no longer support the option to start a virtual machine when the Mac starts.

To configure Parallels Desktop to run as a service, do the following:

1. Open the virtual machine configuration dialog.
2. Click Options and then select Startup and Shutdown.
3. In the Start Automatically menu, select When Mac starts. This tells the Parallels Desktop service to start the virtual machine automatically when macOS starts.
4. In the Startup delay field, set the automatic startup delay in seconds. If you have multiple virtual machines with no autostart delay set, they will start concurrently when you start or restart the host computer. By using the autostart delay you can reduce the load on the host during startup. The autostart delay option can also be helpful when one or more virtual machines depend on a service running in another virtual machine. By setting the autostart delay option for virtual machines, you can ensure that the virtual machine providing the service is up and running before the other virtual machines are started. You can also set the startup delay using a command line interface (see below).
5. In the On Mac Shutdown menu, select Suspend. This tells the Parallels Desktop service to suspend the virtual machine when the Mac is shut down or restarted.
6. In the On Windows Close menu, select Keep running in background (or Ask me what to do if you want a dialog to be displayed when you close the virtual machine window). This way the virtual machine will not be accidentally shut down or suspended when you open and close its window while Parallels Desktop is running as a service.
7. Set the rest of the options according to your usual preferences.

Note: please be advised that to use this feature Parallels Desktop should be granted with Full Disk Access in macOS System Preferences: System Preferences > Security & Privacy > Privacy tab > select Full Disk Access > make sure Parallels Desktop is added to the list (add it in case it's not added).

You may now close the virtual machine window and the Parallels Desktop application. This will only close the graphical user interface. The Parallels Desktop service and the virtual machines will continue to run in the background.