Feature: Registry for drivers and expose driver info in CLI

cmd/limactl/start.go

@@ -21,6 +21,7 @@ import (
 	"github.com/lima-vm/lima/pkg/limatmpl"
 	"github.com/lima-vm/lima/pkg/limayaml"
 	networks "github.com/lima-vm/lima/pkg/networks/reconcile"
+	"github.com/lima-vm/lima/pkg/registry"
 	"github.com/lima-vm/lima/pkg/store"
 	"github.com/lima-vm/lima/pkg/store/filenames"
 	"github.com/lima-vm/lima/pkg/templatestore"
@@ -32,6 +33,7 @@ func registerCreateFlags(cmd *cobra.Command, commentPrefix string) {
 	flags := cmd.Flags()
 	flags.String("name", "", commentPrefix+"Override the instance name")
 	flags.Bool("list-templates", false, commentPrefix+"List available templates and exit")
+	flags.Bool("list-drivers", false, commentPrefix+"List available drivers and exit")
 	editflags.RegisterCreate(cmd, commentPrefix)
 }
 
@@ -393,6 +395,14 @@ func createStartActionCommon(cmd *cobra.Command, _ []string) (exit bool, err err
 			_, _ = fmt.Fprintln(w, f.Name)
 		}
 		return true, nil
+	} else if listDrivers, err := cmd.Flags().GetBool("list-drivers"); err != nil {
+		return true, err
+	} else if listDrivers {
+		w := cmd.OutOrStdout()
+		for k := range registry.List() {
+			_, _ = fmt.Fprintln(w, k)
+		}
+		return true, nil
 	}
 	return false, nil
 }

pkg/limainfo/limainfo.go

@@ -9,8 +9,8 @@ import (
 
 	"github.com/sirupsen/logrus"
 
-	"github.com/lima-vm/lima/pkg/driverutil"
 	"github.com/lima-vm/lima/pkg/limayaml"
+	"github.com/lima-vm/lima/pkg/registry"
 	"github.com/lima-vm/lima/pkg/store/dirnames"
 	"github.com/lima-vm/lima/pkg/templatestore"
 	"github.com/lima-vm/lima/pkg/usrlocalsharelima"
@@ -23,9 +23,14 @@ type LimaInfo struct {
 	DefaultTemplate *limayaml.LimaYAML           `json:"defaultTemplate"`
 	LimaHome        string                       `json:"limaHome"`
 	VMTypes         []string                     `json:"vmTypes"`     // since Lima v0.14.2
+	VMTypesEx       map[string]DriverExt         `json:"vmTypesEx"`   // since Lima v2.0.0
 	GuestAgents     map[limayaml.Arch]GuestAgent `json:"guestAgents"` // since Lima v1.1.0
 }
 
+type DriverExt struct {
+	Location string `json:"location,omitempty"` // since Lima v2.0.0
+}
+
 type GuestAgent struct {
 	Location string `json:"location"` // since Lima v1.1.0
 }
@@ -42,10 +47,25 @@ func New() (*LimaInfo, error) {
 	if err != nil {
 		return nil, err
 	}
+
+	reg := registry.List()
+	if len(reg) == 0 {
+		return nil, errors.New("no VM types found; ensure that the drivers are properly registered")
+	}
+	vmTypesEx := make(map[string]DriverExt)
+	var vmTypes []string
+	for name, path := range reg {
+		vmTypesEx[name] = DriverExt{
+			Location: path,
+		}
+		vmTypes = append(vmTypes, name)
+	}
+
 	info := &LimaInfo{
 		Version:         version.Version,
 		DefaultTemplate: y,
-		VMTypes:         driverutil.Drivers(),
+		VMTypes:         vmTypes,
+		VMTypesEx:       vmTypesEx,
 		GuestAgents:     make(map[limayaml.Arch]GuestAgent),
 	}
 	info.Templates, err = templatestore.Templates()

pkg/registry/registry.go

@@ -0,0 +1,183 @@
+// SPDX-FileCopyrightText: Copyright The Lima Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package registry
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+
+	"github.com/sirupsen/logrus"
+
+	"github.com/lima-vm/lima/pkg/driver"
+	"github.com/lima-vm/lima/pkg/driver/vz"
+	"github.com/lima-vm/lima/pkg/driver/wsl2"
+	"github.com/lima-vm/lima/pkg/limayaml"
+	"github.com/lima-vm/lima/pkg/usrlocalsharelima"
+)
+
+const (
+	Internal = "internal"
+)
+
+type ExternalDriver struct {
+	Name         string
+	InstanceName string
+	Command      *exec.Cmd
+	SocketPath   string
+	Path         string
+	Ctx          context.Context
+	Logger       *logrus.Logger
+	CancelFunc   context.CancelFunc
+}
+
+var (
+	internalDrivers = make(map[string]driver.Driver)
+	ExternalDrivers = make(map[string]*ExternalDriver)
+)
+
+func List() map[string]string {
+	if err := discoverDrivers(); err != nil {
+		logrus.Warnf("Error discovering drivers: %v", err)
+	}
+
+	vmTypes := make(map[string]string)
+	for name := range internalDrivers {
+		vmTypes[name] = Internal
+	}
+	for name, d := range ExternalDrivers {
+		vmTypes[name] = d.Path
+	}
+
+	// This block will be removed while merging the internal driver pull request(#3693).
+	if len(vmTypes) == 0 {
+		vmTypes[limayaml.QEMU] = Internal
+		if vz.Enabled {
+			vmTypes[limayaml.VZ] = Internal
+		}
+		if wsl2.Enabled {
+			vmTypes[limayaml.WSL2] = Internal
+		}
+	}
+
+	return vmTypes
+}
+
+func Get(name string) (*ExternalDriver, driver.Driver, bool) {
+	if err := discoverDrivers(); err != nil {
+		logrus.Warnf("Error discovering drivers: %v", err)
+	}
+
+	internalDriver, exists := internalDrivers[name]
+	if !exists {
+		externalDriver, exists := ExternalDrivers[name]
+		if exists {
+			return externalDriver, nil, exists
+		}
+	}
+	return nil, internalDriver, exists
+}
+
+func registerExternalDriver(name, path string) {
+	if _, exists := ExternalDrivers[name]; exists {
+		return
+	}
+
+	if _, exists := internalDrivers[name]; exists {
+		logrus.Debugf("Driver %q is already registered as an internal driver, skipping external registration", name)
+		return
+	}
+
+	ExternalDrivers[name] = &ExternalDriver{
+		Name:   name,
+		Path:   path,
+		Logger: logrus.New(),
+	}
+}
+
+func discoverDrivers() error {
+	prefix, err := usrlocalsharelima.Prefix()
+	if err != nil {
+		return err
+	}
+	stdDriverDir := filepath.Join(prefix, "libexec", "lima")
+
+	logrus.Debugf("Discovering external drivers in %s", stdDriverDir)
+	if _, err := os.Stat(stdDriverDir); err == nil {
+		if err := discoverDriversInDir(stdDriverDir); err != nil {
+			logrus.Warnf("Error discovering external drivers in %q: %v", stdDriverDir, err)
+		}
+	}
+
+	if driverPaths := os.Getenv("LIMA_DRIVERS_PATH"); driverPaths != "" {
+		paths := filepath.SplitList(driverPaths)
+		for _, path := range paths {
+			if path == "" {
+				continue
+			}
+
+			info, err := os.Stat(path)
+			if err != nil {
+				logrus.Warnf("Error accessing external driver path %q: %v", path, err)
+				continue
+			}
+
+			if info.IsDir() {
+				if err := discoverDriversInDir(path); err != nil {
+					logrus.Warnf("Error discovering external drivers in %q: %v", path, err)
+				}
+			} else if isExecutable(info.Mode()) {
+				registerDriverFile(path)
+			}
+		}
+	}
+
+	return nil
+}
+
+func discoverDriversInDir(dir string) error {
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		return fmt.Errorf("failed to read driver directory %q: %w", dir, err)
+	}
+
+	for _, entry := range entries {
+		if entry.IsDir() {
+			continue
+		}
+
+		info, err := entry.Info()
+		if err != nil {
+			logrus.Warnf("Failed to get info for %q: %v", entry.Name(), err)
+			continue
+		}
+
+		if !isExecutable(info.Mode()) {
+			continue
+		}
+
+		driverPath := filepath.Join(dir, entry.Name())
+		registerDriverFile(driverPath)
+	}
+
+	return nil
+}
+
+func registerDriverFile(path string) {
+	base := filepath.Base(path)
+	if !strings.HasPrefix(base, "lima-driver-") {
+		return
+	}
+
+	name := strings.TrimPrefix(base, "lima-driver-")
+
+	registerExternalDriver(name, path)
+}
+
+func isExecutable(mode os.FileMode) bool {
+	return mode&0o111 != 0
+}

pkg/usrlocalsharelima/usrlocalsharelima.go

@@ -165,3 +165,12 @@ func chooseGABinary(candidates []string) (string, error) {
 		return entries[0], nil
 	}
 }
+
+// Prefix returns the <PREFIX> directory, which is two levels above the lima share directory.
+func Prefix() (string, error) {
+	dir, err := Dir()
+	if err != nil {
+		return "", err
+	}
+	return filepath.Dir(filepath.Dir(dir)), nil
+}