func runVMM()

in main.go [70:151]
65 lines of code
14 McCabe index (conditional complexity)

func runVMM(ctx context.Context, opts *options) error {
	// convert options to a firecracker config
	fcCfg, err := opts.getFirecrackerConfig()
	if err != nil {
		log.Errorf("Error: %s", err)
		return err
	}
	logger := log.New()

	if opts.Debug {
		log.SetLevel(log.DebugLevel)
		logger.SetLevel(log.DebugLevel)
	}

	vmmCtx, vmmCancel := context.WithCancel(ctx)
	defer vmmCancel()

	machineOpts := []firecracker.Opt{
		firecracker.WithLogger(log.NewEntry(logger)),
	}

	var firecrackerBinary string
	if len(opts.FcBinary) != 0 {
		firecrackerBinary = opts.FcBinary
	} else {
		firecrackerBinary, err = exec.LookPath(firecrackerDefaultPath)
		if err != nil {
			return err
		}
	}

	finfo, err := os.Stat(firecrackerBinary)
	if os.IsNotExist(err) {
		return fmt.Errorf("Binary %q does not exist: %v", firecrackerBinary, err)
	}

	if err != nil {
		return fmt.Errorf("Failed to stat binary, %q: %v", firecrackerBinary, err)
	}

	if finfo.IsDir() {
		return fmt.Errorf("Binary, %q, is a directory", firecrackerBinary)
	} else if finfo.Mode()&executableMask == 0 {
		return fmt.Errorf("Binary, %q, is not executable. Check permissions of binary", firecrackerBinary)
	}

	// if the jailer is used, the final command will be built in NewMachine()
	if fcCfg.JailerCfg == nil {
		cmd := firecracker.VMCommandBuilder{}.
			WithBin(firecrackerBinary).
			WithSocketPath(fcCfg.SocketPath).
			WithStdin(os.Stdin).
			WithStdout(os.Stdout).
			WithStderr(os.Stderr).
			Build(ctx)

		machineOpts = append(machineOpts, firecracker.WithProcessRunner(cmd))
	}

	m, err := firecracker.NewMachine(vmmCtx, fcCfg, machineOpts...)
	if err != nil {
		return fmt.Errorf("Failed creating machine: %s", err)
	}

	if err := m.Start(vmmCtx); err != nil {
		return fmt.Errorf("Failed to start machine: %v", err)
	}
	defer m.StopVMM()

	if opts.validMetadata != nil {
		m.SetMetadata(vmmCtx, opts.validMetadata)
	}

	installSignalHandlers(vmmCtx, m)

	// wait for the VMM to exit
	if err := m.Wait(vmmCtx); err != nil {
		return fmt.Errorf("Wait returned an error %s", err)
	}
	log.Printf("Start machine was happy")
	return nil
}