Process self-destruction mechanism for vm-supervisor

[yaroslav-gwit]

There is no exact number to be named, but for some weird reason after issuing 4-6 reboot commands from within the VM, the vm-supervisor process can't start a new bhyve child.

To resolve this issue I'll need to create a self-destruction mechanism for the parent process for vm-supervisor, whenever it sees that the VM was rebooted. And then simply start a new detached process that will execute hoster vm start vm-name again to start the VM.

[yaroslav-gwit]

Completely re-written the main() function loop to deal with all possible child exit cases:

		done := make(chan error)
		startVmProcess(hupCmd, done)
		wg.Wait()

		processErr := <-done
		if processErr != nil {
			logFileOutput(LOG_SUPERVISOR, "VM child process ended with a non-zero exit code: " + processErr.Error())
		}

		processExitStatus, correctReturnType := processErr.(*exec.ExitError)
		if correctReturnType {
			exitCode := processExitStatus.ProcessState.ExitCode()
			if exitCode == 1 || exitCode == 2 {
				logFileOutput(LOG_SUPERVISOR, "Bhyve received a shutdown signal: " + strconv.Itoa(exitCode) + ". Executing the shutdown sequence...")
				logFileOutput(LOG_SUPERVISOR, "Shutting down -> Performing network cleanup")
				cmd.NetworkCleanup(vmName, true)
				logFileOutput(LOG_SUPERVISOR, "Shutting down -> Performing Bhyve cleanup")
				cmd.BhyvectlDestroy(vmName, true)
				logFileOutput(LOG_SUPERVISOR, "SUPERVISED SESSION ENDED. The VM has been shutdown.")
				os.Exit(0)
			} else {
				logFileOutput(LOG_SUPERVISOR, "Bhyve returned a panic exit code: " + strconv.Itoa(exitCode))
				logFileOutput(LOG_SUPERVISOR, "Shutting down all VM related processes and performing system clean up")
				cmd.NetworkCleanup(vmName, true)
				cmd.BhyvectlDestroy(vmName, true)
				logFileOutput(LOG_SUPERVISOR, "SUPERVISED SESSION ENDED. Unexpected exit code.")
				os.Exit(101)
			}
		} else {
			logFileOutput(LOG_SUPERVISOR, "Bhyve received a reboot signal. Executing the reboot sequence...")
			logFileOutput(LOG_SUPERVISOR, "Rebooting -> Performing network cleanup")
			cmd.NetworkCleanup(vmName, true)
			logFileOutput(LOG_SUPERVISOR, "Rebooting -> Performing Bhyve cleanup")
			cmd.BhyvectlDestroy(vmName, true)
			logFileOutput(LOG_SUPERVISOR, "SUPERVISED SESSION ENDED. The VM will start back up in a moment.")
			restartVmProcess(vmName)
			os.Exit(0)
		}
		logFileOutput(LOG_SUPERVISOR, "SUPERVISED SESSION ENDED. SOMETHING UNPREDICTED HAPPENED! THE PROCESS HAD TO EXIT!")
		cmd.NetworkCleanup(vmName, true)
		cmd.BhyvectlDestroy(vmName, true)
		os.Exit(1000)
	}

The issue can be closed, as VM Supervisor now works as expected.