cmd/vfkit: add --pidfile flag to write vfkit process PID to file

Introduce a new --pidfile flag to optionally specify a file where the
running vfkit process writes its PID. This allows easier process
management and monitoring.

Author: vyasgun

cmd/vfkit/main.go

@@ -35,6 +35,7 @@ import (
 	"github.com/Code-Hex/vz/v3"
 	"github.com/crc-org/vfkit/pkg/cmdline"
 	"github.com/crc-org/vfkit/pkg/config"
+	"github.com/crc-org/vfkit/pkg/process"
 	"github.com/crc-org/vfkit/pkg/rest"
 	restvf "github.com/crc-org/vfkit/pkg/rest/vf"
 	"github.com/crc-org/vfkit/pkg/vf"
@@ -100,14 +101,26 @@ func newVMConfiguration(opts *cmdline.Options) (*config.VirtualMachine, error) {
 		opts.Devices = append(opts.Devices, fmt.Sprintf("virtio-blk,path=%s", cloudInitISO))
 	}
 
+	if opts.PidFile != "" {
+		execPath, err := os.Executable()
+		if err != nil {
+			return nil, fmt.Errorf("could not determine executable path: %w", err)
+		}
+		vfProcess := process.New(os.Args[0], opts.PidFile, execPath)
+		pid := os.Getpid()
+		err = vfProcess.WritePidFile(pid)
+		if err != nil {
+			return nil, fmt.Errorf("could not write PID: %v", err)
+		}
+	}
+
 	if err := vmConfig.AddDevicesFromCmdLine(opts.Devices); err != nil {
 		return nil, err
 	}
 
 	if err := vmConfig.AddIgnitionFileFromCmdLine(opts.IgnitionPath); err != nil {
 		return nil, fmt.Errorf("failed to add ignition file: %w", err)
 	}
-
 	return vmConfig, nil
 }
 

pkg/cmdline/cmdline.go

@@ -27,6 +27,8 @@ type Options struct {
 	IgnitionPath string
 
 	CloudInitFiles stringSliceValue
+
+	PidFile string
 }
 
 const DefaultRestfulURI = "none://"
@@ -56,4 +58,5 @@ func AddFlags(cmd *cobra.Command, opts *Options) {
 
 	cmd.Flags().StringVar(&opts.IgnitionPath, "ignition", "", "path to the ignition file")
 	cmd.Flags().VarP(&opts.CloudInitFiles, "cloud-init", "", "path to user-data and meta-data cloud-init configuration files")
+	cmd.Flags().StringVar(&opts.PidFile, "pidfile", "", "path to the pid file")
 }

pkg/config/config.go

@@ -32,6 +32,7 @@ type VirtualMachine struct {
 	Devices    []VirtioDevice `json:"devices,omitempty"`
 	Timesync   *TimeSync      `json:"timesync,omitempty"`
 	Ignition   *Ignition      `json:"ignition,omitempty"`
+	PidFile    string         `json:"pidFile,omitempty"`
 }
 
 // TimeSync enables synchronization of the host time to the linux guest after the host was suspended.

pkg/config/json_test.go

@@ -231,7 +231,7 @@ var jsonStabilityTests = map[string]jsonStabilityTest{
 
 			return vm
 		},
-		skipFields:   []string{"Bootloader", "Devices", "Timesync", "Ignition"},
+		skipFields:   []string{"Bootloader", "Devices", "Timesync", "Ignition", "PidFile"},
 		expectedJSON: `{"vcpus":3,"memoryBytes":3,"bootloader":{"kind":"linuxBootloader","vmlinuzPath":"/vmlinuz","kernelCmdLine":"console=hvc0","initrdPath":"/initrd"},"devices":[{"kind":"virtiorng"}],"timesync":{"vsockPort":1234}}`,
 	},
 	"RosettaShare": {

pkg/process/process.go

@@ -80,8 +80,6 @@ func (p *Process) findProcess() (*process.Process, error) {
 		return nil, fmt.Errorf("cannot find process exe: %v", err)
 	}
 	if exe != p.ExecutablePath {
-		fmt.Println("HII", exe, p.ExecutablePath)
-
 		return nil, os.ErrNotExist
 	}
 	return proc, nil