Support for inotify in mounted directories

Signed-off-by: Balaji Vijayakumar <kuttibalaji.v6@gmail.com>

cmd/limactl/editflags/editflags.go

@@ -49,6 +49,7 @@ func registerEdit(cmd *cobra.Command, commentPrefix string) {
 	})
 
 	flags.Bool("mount-writable", false, commentPrefix+"make all mounts writable")
+	flags.Bool("mount-inotify", false, commentPrefix+"enable inotify for mounts")
 
 	flags.StringSlice("network", nil, commentPrefix+"additional networks, e.g., \"vzNAT\" or \"lima:shared\" to assign vmnet IP")
 	_ = cmd.RegisterFlagCompletionFunc("network", func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
@@ -154,6 +155,7 @@ func YQExpressions(flags *flag.FlagSet, newInstance bool) ([]string, error) {
 			false,
 		},
 		{"mount-type", d(".mountType = %q"), false, false},
+		{"mount-inotify", d(".mountInotify = %s"), false, true},
 		{"mount-writable", d(".mounts[].writable = %s"), false, false},
 		{
 			"network",

examples/default.yaml

@@ -103,6 +103,11 @@ mounts:
 # 🟢 Builtin default: "reverse-sshfs" (for QEMU), "virtiofs" (for vz)
 mountType: null
 
+# Enable inotify support for mounted directories (EXPERIMENTAL)
+# 🟢 Builtin default: Disabled by default
+mountInotify: null
+
+
 # Lima disks to attach to the instance. The disks will be accessible from inside the
 # instance, labeled by name. (e.g. if the disk is named "data", it will be labeled
 # "lima-data" inside the instance). The disk will be mounted inside the instance at

go.mod

@@ -33,6 +33,7 @@ require (
 	github.com/nxadm/tail v1.4.11
 	github.com/opencontainers/go-digest v1.0.0
 	github.com/pbnjay/memory v0.0.0-20210728143218-7b4eea64cf58
+	github.com/rjeczalik/notify v0.9.3
 	github.com/sethvargo/go-password v0.2.0
 	github.com/sirupsen/logrus v1.9.3
 	github.com/spf13/cobra v1.8.0

go.sum

@@ -221,6 +221,8 @@ github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZb
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/rivo/uniseg v0.2.0 h1:S1pD9weZBuJdFmowNwbpi7BJ8TNftyUImj/0WQi72jY=
 github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
+github.com/rjeczalik/notify v0.9.3 h1:6rJAzHTGKXGj76sbRgDiDcYj/HniypXmSJo1SWakZeY=
+github.com/rjeczalik/notify v0.9.3/go.mod h1:gF3zSOrafR9DQEWSE8TjfI9NkooDxbyT4UgRGKZA0lc=
 github.com/rogpeppe/go-internal v1.10.0 h1:TMyTOH3F/DB16zRVcYyreMH6GnZZrwQVAoYjRBZyWFQ=
 github.com/russross/blackfriday/v2 v2.1.0 h1:JIOH55/0cWyOuilr9/qlrm0BSXldqnqwMsf35Ld67mk=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
@@ -305,6 +307,7 @@ golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJ
 golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.5.0 h1:60k92dhOjHxJkrqnwsfl8KuaHbn/5dl0lUPUklKo3qE=
 golang.org/x/sync v0.5.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
+golang.org/x/sys v0.0.0-20180926160741-c2ed4eda69e7/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190312061237-fead79001313/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

pkg/guestagent/api/api.go

@@ -32,3 +32,8 @@ type Event struct {
 	LocalPortsRemoved []IPPort `json:"localPortsRemoved,omitempty"`
 	Errors            []string `json:"errors,omitempty"`
 }
+
+type InotifyEvent struct {
+	Location string    `json:"location,omitempty"`
+	Time     time.Time `json:"time,omitempty"`
+}

pkg/guestagent/api/client/client.go

@@ -4,6 +4,7 @@ package client
 // Apache License 2.0
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
 	"fmt"
@@ -18,12 +19,13 @@ type GuestAgentClient interface {
 	HTTPClient() *http.Client
 	Info(context.Context) (*api.Info, error)
 	Events(context.Context, func(api.Event)) error
+	Inotify(context.Context, api.InotifyEvent) error
 }
 
 // NewGuestAgentClient creates a client.
 // remote is a path to the UNIX socket, without unix:// prefix or a remote hostname/IP address.
-func NewGuestAgentClient(conn net.Conn) (GuestAgentClient, error) {
-	hc, err := httpclientutil.NewHTTPClientWithConn(conn)
+func NewGuestAgentClient(dialFn func(ctx context.Context) (net.Conn, error)) (GuestAgentClient, error) {
+	hc, err := httpclientutil.NewHTTPClientWithDialFn(dialFn)
 	if err != nil {
 		return nil, err
 	}
@@ -81,3 +83,20 @@ func (c *client) Events(ctx context.Context, onEvent func(api.Event)) error {
 		onEvent(ev)
 	}
 }
+
+func (c *client) Inotify(ctx context.Context, event api.InotifyEvent) error {
+	buffer := &bytes.Buffer{}
+	encoder := json.NewEncoder(buffer)
+	err := encoder.Encode(&event)
+	if err != nil {
+		return err
+	}
+
+	u := fmt.Sprintf("http://%s/%s/inotify", c.dummyHost, c.version)
+	resp, err := httpclientutil.Post(ctx, c.HTTPClient(), u, buffer)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	return nil
+}

pkg/guestagent/api/server/server.go

@@ -76,8 +76,28 @@ func (b *Backend) GetEvents(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+// PostInotify is the handler for POST /v{N}/inotify.
+func (b *Backend) PostInotify(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+	_, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	inotifyEvent := api.InotifyEvent{}
+	decoder := json.NewDecoder(r.Body)
+	if err := decoder.Decode(&inotifyEvent); err != nil {
+		logrus.Warn(err)
+		return
+	}
+	go b.Agent.HandleInotify(inotifyEvent)
+
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	_, _ = w.Write([]byte(""))
+}
+
 func AddRoutes(r *mux.Router, b *Backend) {
 	v1 := r.PathPrefix("/v1").Subrouter()
 	v1.Path("/info").Methods("GET").HandlerFunc(b.GetInfo)
 	v1.Path("/events").Methods("GET").HandlerFunc(b.GetEvents)
+	v1.Path("/inotify").Methods("POST").HandlerFunc(b.PostInotify)
 }

pkg/guestagent/guestagent.go

@@ -10,4 +10,5 @@ type Agent interface {
 	Info(ctx context.Context) (*api.Info, error)
 	Events(ctx context.Context, ch chan api.Event)
 	LocalPorts(ctx context.Context) ([]api.IPPort, error)
+	HandleInotify(event api.InotifyEvent)
 }

pkg/guestagent/guestagent_linux.go

@@ -3,6 +3,7 @@ package guestagent
 import (
 	"context"
 	"errors"
+	"os"
 	"reflect"
 	"sync"
 	"syscall"
@@ -333,3 +334,13 @@ func (a *agent) fixSystemTimeSkew() {
 		ticker.Stop()
 	}
 }
+
+func (a *agent) HandleInotify(event api.InotifyEvent) {
+	location := event.Location
+	if _, err := os.Stat(location); err == nil {
+		err := os.Chtimes(location, event.Time.Local(), event.Time.Local())
+		if err != nil {
+			logrus.Errorf("error in inotify handle. Event: %s, Error: %s", event, err)
+		}
+	}
+}

pkg/hostagent/hostagent.go

@@ -555,6 +555,16 @@ func (a *HostAgent) watchGuestAgentEvents(ctx context.Context) {
 		}
 		return errors.Join(errs...)
 	})
+
+	go func() {
+		if a.y.MountInotify != nil && *a.y.MountInotify {
+			err := a.startInotify(ctx)
+			if err != nil {
+				logrus.WithError(err).Warn("failed to start inotify", err)
+			}
+		}
+	}()
+
 	for {
 		client, err := a.getOrCreateClient(ctx)
 		if err == nil {
@@ -590,13 +600,8 @@ func (a *HostAgent) getOrCreateClient(ctx context.Context) (guestagentclient.Gue
 	return a.client, err
 }
 
-func (a *HostAgent) createClient(ctx context.Context) (guestagentclient.GuestAgentClient, error) {
-	conn, err := a.driver.GuestAgentConn(ctx)
-	if err != nil {
-		return nil, err
-	}
-
-	return guestagentclient.NewGuestAgentClient(conn)
+func (a *HostAgent) createClient(_ context.Context) (guestagentclient.GuestAgentClient, error) {
+	return guestagentclient.NewGuestAgentClient(a.driver.GuestAgentConn)
 }
 
 func (a *HostAgent) processGuestAgentEvents(ctx context.Context, client guestagentclient.GuestAgentClient) error {

pkg/hostagent/inotify.go

@@ -0,0 +1,84 @@
+package hostagent
+
+import (
+	"context"
+	"os"
+	"path"
+
+	guestagentapi "github.com/lima-vm/lima/pkg/guestagent/api"
+	"github.com/lima-vm/lima/pkg/localpathutil"
+	"github.com/rjeczalik/notify"
+	"github.com/sirupsen/logrus"
+)
+
+const CacheSize = 10000
+
+var inotifyCache = make(map[string]string)
+
+func (a *HostAgent) startInotify(ctx context.Context) error {
+	mountWatchCh := make(chan notify.EventInfo, 128)
+	err := a.setupWatchers(mountWatchCh)
+	if err != nil {
+		return err
+	}
+
+	for {
+		select {
+		case <-ctx.Done():
+			return nil
+		case watchEvent := <-mountWatchCh:
+			client, err := a.getOrCreateClient(ctx)
+			if err != nil {
+				logrus.Error("failed to create client for inotify", err)
+			}
+			stat, err := os.Stat(watchEvent.Path())
+			if err != nil {
+				continue
+			}
+
+			if filterEvents(watchEvent) {
+				continue
+			}
+
+			event := guestagentapi.InotifyEvent{Location: watchEvent.Path(), Time: stat.ModTime().UTC()}
+			err = client.Inotify(ctx, event)
+
+			if err != nil {
+				logrus.WithError(err).Warn("failed to send inotify", err)
+			}
+		}
+	}
+}
+
+func (a *HostAgent) setupWatchers(events chan notify.EventInfo) error {
+	for _, m := range a.y.Mounts {
+		if *m.Writable {
+			location, err := localpathutil.Expand(m.Location)
+			if err != nil {
+				return err
+			}
+			logrus.Infof("enable inotify for writable mount: %s", location)
+			err = notify.Watch(path.Join(location, "..."), events, notify.Create|notify.Write)
+			if err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+func filterEvents(event notify.EventInfo) bool {
+	eventPath := event.Path()
+	_, ok := inotifyCache[eventPath]
+	if ok {
+		// Ignore the duplicate inotify on mounted directories, so always remove a entry if already present
+		delete(inotifyCache, eventPath)
+		return true
+	}
+	inotifyCache[eventPath] = ""
+
+	if len(inotifyCache) >= CacheSize {
+		inotifyCache = make(map[string]string)
+	}
+	return false
+}

pkg/httpclientutil/httpclientutil.go

@@ -32,6 +32,22 @@ func Get(ctx context.Context, c *http.Client, url string) (*http.Response, error
 	return resp, nil
 }
 
+func Post(ctx context.Context, c *http.Client, url string, body io.Reader) (*http.Response, error) {
+	req, err := http.NewRequestWithContext(ctx, "POST", url, body)
+	if err != nil {
+		return nil, err
+	}
+	resp, err := c.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	if err := Successful(resp); err != nil {
+		resp.Body.Close()
+		return nil, err
+	}
+	return resp, nil
+}
+
 func readAtMost(r io.Reader, maxBytes int) ([]byte, error) {
 	lr := &io.LimitedReader{
 		R: r,
@@ -85,13 +101,13 @@ func Successful(resp *http.Response) error {
 	return nil
 }
 
-// NewHTTPClientWithConn creates a client.
+// NewHTTPClientWithDialFn creates a client.
 // conn is a raw net.Conn instance.
-func NewHTTPClientWithConn(conn net.Conn) (*http.Client, error) {
+func NewHTTPClientWithDialFn(dialFn func(ctx context.Context) (net.Conn, error)) (*http.Client, error) {
 	hc := &http.Client{
 		Transport: &http.Transport{
 			DialContext: func(ctx context.Context, _, _ string) (net.Conn, error) {
-				return conn, nil
+				return dialFn(ctx)
 			},
 		},
 	}

pkg/limayaml/defaults.go

@@ -525,6 +525,16 @@ func FillDefault(y, d, o *LimaYAML, filePath string) {
 		}
 	}
 
+	if y.MountInotify == nil {
+		y.MountInotify = d.MountInotify
+	}
+	if o.MountInotify != nil {
+		y.MountInotify = o.MountInotify
+	}
+	if y.MountInotify == nil {
+		y.MountInotify = ptr.Of(false)
+	}
+
 	// Combine all mounts; highest priority entry determines writable status.
 	// Only works for exact matches; does not normalize case or resolve symlinks.
 	mounts := make([]Mount, 0, len(d.Mounts)+len(y.Mounts)+len(o.Mounts))

pkg/limayaml/defaults_test.go

@@ -203,6 +203,8 @@ func TestFillDefault(t *testing.T) {
 
 	expect.MountType = ptr.Of(NINEP)
 
+	expect.MountInotify = ptr.Of(false)
+
 	expect.Provision = y.Provision
 	expect.Provision[0].Mode = ProvisionModeSystem
 
@@ -390,6 +392,7 @@ func TestFillDefault(t *testing.T) {
 		"default": d.HostResolver.Hosts["default"],
 	}
 	expect.MountType = ptr.Of(VIRTIOFS)
+	expect.MountInotify = ptr.Of(false)
 	expect.CACertificates.RemoveDefaults = ptr.Of(true)
 	expect.CACertificates.Certs = []string{
 		"-----BEGIN CERTIFICATE-----\nYOUR-ORGS-TRUSTED-CA-CERT\n-----END CERTIFICATE-----\n",
@@ -520,6 +523,7 @@ func TestFillDefault(t *testing.T) {
 				},
 			},
 		},
+		MountInotify: ptr.Of(true),
 		Provision: []Provision{
 			{
 				Script: "#!/bin/true",
@@ -596,6 +600,7 @@ func TestFillDefault(t *testing.T) {
 	expect.Mounts[0].Virtiofs.QueueSize = ptr.Of(2048)
 
 	expect.MountType = ptr.Of(NINEP)
+	expect.MountInotify = ptr.Of(true)
 
 	// o.Networks[1] is overriding the d.Networks[0].Lima entry for the "def0" interface
 	expect.Networks = append(append(d.Networks, y.Networks...), o.Networks[0])

pkg/limayaml/limayaml.go

@@ -18,6 +18,7 @@ type LimaYAML struct {
 	AdditionalDisks    []Disk          `yaml:"additionalDisks,omitempty" json:"additionalDisks,omitempty"`
 	Mounts             []Mount         `yaml:"mounts,omitempty" json:"mounts,omitempty"`
 	MountType          *MountType      `yaml:"mountType,omitempty" json:"mountType,omitempty"`
+	MountInotify       *bool           `yaml:"mountInotify,omitempty" json:"mountInotify,omitempty"`
 	SSH                SSH             `yaml:"ssh,omitempty" json:"ssh,omitempty"` // REQUIRED (FIXME)
 	Firmware           Firmware        `yaml:"firmware,omitempty" json:"firmware,omitempty"`
 	Audio              Audio           `yaml:"audio,omitempty" json:"audio,omitempty"`

pkg/limayaml/validate.go

@@ -471,4 +471,7 @@ func warnExperimental(y LimaYAML) {
 	if y.Audio.Device != nil && *y.Audio.Device != "" {
 		logrus.Warn("`audio.device` is experimental")
 	}
+	if y.MountInotify != nil && *y.MountInotify {
+		logrus.Warn("`mountInotify` is experimental")
+	}
 }

pkg/vz/vz_driver_darwin.go

@@ -54,6 +54,7 @@ func (l *LimaVzDriver) Validate() error {
 		"Disk",
 		"Mounts",
 		"MountType",
+		"MountInotify",
 		"SSH",
 		"Firmware",
 		"Provision",