Implement limactl clone

`limactl clone OLDINST NEWINST` clones an instance.

Not to be confused with `limactl copy SRC DST` (copy files).

Fix issue 3658

Signed-off-by: Akihiro Suda <[email protected]>

Author: AkihiroSuda

cmd/limactl/clone.go

@@ -0,0 +1,117 @@
+// SPDX-FileCopyrightText: Copyright The Lima Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package main
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/spf13/cobra"
+
+	"github.com/lima-vm/lima/cmd/limactl/editflags"
+	"github.com/lima-vm/lima/pkg/instance"
+	"github.com/lima-vm/lima/pkg/limayaml"
+	networks "github.com/lima-vm/lima/pkg/networks/reconcile"
+	"github.com/lima-vm/lima/pkg/store"
+	"github.com/lima-vm/lima/pkg/store/filenames"
+	"github.com/lima-vm/lima/pkg/yqutil"
+)
+
+func newCloneCommand() *cobra.Command {
+	cloneCommand := &cobra.Command{
+		Use:   "clone OLDINST NEWINST",
+		Short: "Clone an instance of Lima",
+		Long: `Clone an instance of Lima.
+
+Not to be confused with 'limactl copy' ('limactl cp').
+`,
+		Args:              WrapArgsError(cobra.ExactArgs(2)),
+		RunE:              cloneAction,
+		ValidArgsFunction: cloneBashComplete,
+		GroupID:           advancedCommand,
+	}
+	editflags.RegisterEdit(cloneCommand)
+	return cloneCommand
+}
+
+func cloneAction(cmd *cobra.Command, args []string) error {
+	ctx := cmd.Context()
+	flags := cmd.Flags()
+	tty, err := flags.GetBool("tty")
+	if err != nil {
+		return err
+	}
+
+	oldInstName, newInstName := args[0], args[1]
+	oldInst, err := store.Inspect(oldInstName)
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return fmt.Errorf("instance %q not found", oldInstName)
+		}
+		return err
+	}
+
+	newInst, err := instance.Clone(ctx, oldInst, newInstName)
+	if err != nil {
+		return err
+	}
+
+	yqExprs, err := editflags.YQExpressions(flags, false)
+	if err != nil {
+		return err
+	}
+	if len(yqExprs) > 0 {
+		// TODO: reduce duplicated codes across cloneAction and editAction
+		yq := yqutil.Join(yqExprs)
+		filePath := filepath.Join(newInst.Dir, filenames.LimaYAML)
+		yContent, err := os.ReadFile(filePath)
+		if err != nil {
+			return err
+		}
+		yBytes, err := yqutil.EvaluateExpression(yq, yContent)
+		if err != nil {
+			return err
+		}
+		y, err := limayaml.LoadWithWarnings(yBytes, filePath)
+		if err != nil {
+			return err
+		}
+		if err := limayaml.Validate(y, true); err != nil {
+			return saveRejectedYAML(yBytes, err)
+		}
+		if err := limayaml.ValidateAgainstLatestConfig(yBytes, yContent); err != nil {
+			return saveRejectedYAML(yBytes, err)
+		}
+		if err := os.WriteFile(filePath, yBytes, 0o644); err != nil {
+			return err
+		}
+		newInst, err = store.Inspect(newInst.Name)
+		if err != nil {
+			return err
+		}
+	}
+
+	if !tty {
+		// use "start" to start it
+		return nil
+	}
+	startNow, err := askWhetherToStart()
+	if err != nil {
+		return err
+	}
+	if !startNow {
+		return nil
+	}
+	err = networks.Reconcile(ctx, newInst.Name)
+	if err != nil {
+		return err
+	}
+	return instance.Start(ctx, newInst, "", false)
+}
+
+func cloneBashComplete(cmd *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
+	return bashCompleteInstanceNames(cmd)
+}

cmd/limactl/copy.go

@@ -26,6 +26,8 @@ const copyHelp = `Copy files between host and guest
 Prefix guest filenames with the instance name and a colon.
 
 Example: limactl copy default:/etc/os-release .
+
+Not to be confused with 'limactl clone'.
 `
 
 func newCopyCommand() *cobra.Command {

cmd/limactl/main.go

@@ -189,6 +189,7 @@ func newApp() *cobra.Command {
 		newRestartCommand(),
 		newSudoersCommand(),
 		newStartAtLoginCommand(),
+		newCloneCommand(),
 	)
 
 	return rootCmd

hack/test-templates.sh

@@ -49,6 +49,7 @@ declare -A CHECKS=(
 	# snapshot tests are too flaky (especially with archlinux)
 	["snapshot-online"]=""
 	["snapshot-offline"]=""
+	["clone"]=""
 	["port-forwards"]="1"
 	["vmnet"]=""
 	["disk"]=""
@@ -85,6 +86,7 @@ case "$NAME" in
 	CHECKS["disk"]=1
 	CHECKS["snapshot-online"]="1"
 	CHECKS["snapshot-offline"]="1"
+	CHECKS["clone"]="1"
 	CHECKS["mount-path-with-spaces"]="1"
 	CHECKS["provision-data"]="1"
 	CHECKS["param-env-variables"]="1"
@@ -527,6 +529,16 @@ if [[ -n ${CHECKS["snapshot-offline"]} ]]; then
 	limactl snapshot delete "$NAME" --tag snap2
 	limactl start "$NAME"
 fi
+if [[ -n ${CHECKS["clone"]} ]]; then
+	INFO "Testing cloning"
+	limactl stop "$NAME"
+	sleep 3
+	# [hostagent] could not attach disk \"data\", in use by instance \"test-misc-clone\"
+	limactl clone --set '.additionalDisks = null' "$NAME" "${NAME}-clone"
+	limactl start "${NAME}-clone"
+	[ "$(limactl shell "${NAME}-clone" hostname)" = "lima-${NAME}-clone" ]
+	limactl start "$NAME"
+fi
 
 if [[ $NAME == "fedora" && "$(limactl ls --json "$NAME" | jq -r .vmType)" == "vz" ]]; then
 	"${scriptdir}"/test-selinux.sh "$NAME"

pkg/instance/clone.go

@@ -0,0 +1,86 @@
+// SPDX-FileCopyrightText: Copyright The Lima Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package instance
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"slices"
+	"strings"
+
+	continuityfs "github.com/containerd/continuity/fs"
+
+	"github.com/lima-vm/lima/pkg/osutil"
+	"github.com/lima-vm/lima/pkg/store"
+	"github.com/lima-vm/lima/pkg/store/filenames"
+)
+
+func Clone(_ context.Context, oldInst *store.Instance, newInstName string) (*store.Instance, error) {
+	if newInstName == "" {
+		return nil, errors.New("got empty instName")
+	}
+	if oldInst.Name == newInstName {
+		return nil, fmt.Errorf("new instance name %q must be different from %q", newInstName, oldInst.Name)
+	}
+	if oldInst.Status == store.StatusRunning {
+		return nil, errors.New("cannot clone a running instance")
+	}
+
+	newInstDir, err := store.InstanceDir(newInstName)
+	if err != nil {
+		return nil, err
+	}
+
+	// the full path of the socket name must be less than UNIX_PATH_MAX chars.
+	maxSockName := filepath.Join(newInstDir, filenames.LongestSock)
+	if len(maxSockName) >= osutil.UnixPathMax {
+		return nil, fmt.Errorf("instance name %q too long: %q must be less than UNIX_PATH_MAX=%d characters, but is %d",
+			newInstName, maxSockName, osutil.UnixPathMax, len(maxSockName))
+	}
+
+	if err = os.Mkdir(newInstDir, 0o700); err != nil {
+		return nil, err
+	}
+
+	walkDirFn := func(path string, d fs.DirEntry, err error) error {
+		base := filepath.Base(path)
+		if slices.Contains(filenames.SkipOnClone, base) {
+			return nil
+		}
+		for _, ext := range filenames.TmpFileSuffixes {
+			if strings.HasSuffix(path, ext) {
+				return nil
+			}
+		}
+		if err != nil {
+			return err
+		}
+		pathRel, err := filepath.Rel(oldInst.Dir, path)
+		if err != nil {
+			return err
+		}
+		dst := filepath.Join(newInstDir, pathRel)
+		if d.IsDir() {
+			return os.MkdirAll(dst, d.Type().Perm())
+		}
+		// NullifyOnClone contains VzIdentifier.
+		// VzIdentifier file must not be just removed here, as pkg/limayaml depends on
+		// the existence of VzIdentifier for resolving the VM type.
+		if slices.Contains(filenames.NullifyOnClone, base) {
+			return os.WriteFile(dst, nil, 0o666)
+		}
+		// CopyFile attempts copy-on-write when supported by the filesystem
+		return continuityfs.CopyFile(dst, path)
+	}
+
+	if err = filepath.WalkDir(oldInst.Dir, walkDirFn); err != nil {
+		return nil, err
+	}
+
+	return store.Inspect(newInstName)
+}

pkg/instance/stop.go

@@ -131,8 +131,7 @@ func StopForcibly(inst *store.Instance) {
 		logrus.Info("The host agent process seems already stopped")
 	}
 
-	suffixesToBeRemoved := []string{".pid", ".sock", ".tmp"}
-	globPatterns := strings.ReplaceAll(strings.Join(suffixesToBeRemoved, " "), ".", "*.")
+	globPatterns := strings.ReplaceAll(strings.Join(filenames.TmpFileSuffixes, " "), ".", "*.")
 	logrus.Infof("Removing %s under %q", globPatterns, inst.Dir)
 
 	fi, err := os.ReadDir(inst.Dir)
@@ -142,7 +141,7 @@ func StopForcibly(inst *store.Instance) {
 	}
 	for _, f := range fi {
 		path := filepath.Join(inst.Dir, f.Name())
-		for _, suffix := range suffixesToBeRemoved {
+		for _, suffix := range filenames.TmpFileSuffixes {
 			if strings.HasSuffix(path, suffix) {
 				logrus.Infof("Removing %q", path)
 				if err := os.Remove(path); err != nil {

pkg/store/filenames/filenames.go

@@ -91,3 +91,17 @@ const LongestSock = SSHSock + ".1234567890123456"
 func PIDFile(name string) string {
 	return name + ".pid"
 }
+
+// SkipOnClone files should be skipped on cloning an instance.
+var SkipOnClone = []string{
+	Protected,
+}
+
+// NullifyOnClone files should be nullified on cloning an instance.
+// FIXME: this list should be provided by the VM driver.
+var NullifyOnClone = []string{
+	VzIdentifier,
+}
+
+// TmpFileSuffixes is the list of the tmp file suffixes.
+var TmpFileSuffixes = []string{".pid", ".sock", ".tmp"}

pkg/vz/vm_darwin.go

@@ -692,7 +692,8 @@ func attachOtherDevices(_ *driver.BaseDriver, vmConfig *vz.VirtualMachineConfigu
 
 func getMachineIdentifier(driver *driver.BaseDriver) (*vz.GenericMachineIdentifier, error) {
 	identifier := filepath.Join(driver.Instance.Dir, filenames.VzIdentifier)
-	if _, err := os.Stat(identifier); os.IsNotExist(err) {
+	// Empty VzIdentifier can be created on cloning an instance.
+	if st, err := os.Stat(identifier); os.IsNotExist(err) || (st != nil && st.Size() == 0) {
 		machineIdentifier, err := vz.NewGenericMachineIdentifier()
 		if err != nil {
 			return nil, err