nydus: wait nydusd API server ready before mounting share fs

If the API server is not ready, the mount call will fail, so before
mounting share fs, we should wait the nydusd is started and
the API server is ready.

Fixes: #4710

Signed-off-by: liubin <liubin0329@gmail.com>
Signed-off-by: Bin Liu <bin@hyper.sh>

src/runtime/virtcontainers/nydusd.go

@@ -36,6 +36,8 @@ const (
 	infoEndpoint  = "http://unix/api/v1/daemon"
 	mountEndpoint = "http://unix/api/v1/mount"
 
+	nydusdDaemonStateRunning = "RUNNING"
+
 	nydusdStopTimeoutSecs = 5
 
 	defaultHttpClientTimeoutSecs = 30 * time.Second
@@ -73,6 +75,7 @@ var (
 
 type nydusd struct {
 	startFn         func(cmd *exec.Cmd) error // for mock testing
+	waitFn          func() error              // for mock
 	setupShareDirFn func() error              // for mock testing
 	path            string
 	sockPath        string
@@ -115,17 +118,19 @@ func (nd *nydusd) Start(ctx context.Context, onQuit onQuitFunc) (int, error) {
 		"path": nd.path,
 		"args": strings.Join(args, " "),
 	}
-	nd.Logger().WithFields(fields).Info()
+	nd.Logger().WithFields(fields).Info("starting nydusd")
 	if err := nd.startFn(cmd); err != nil {
-		return pid, err
+		return pid, errors.Wrap(err, "failed to start nydusd")
 	}
+	nd.Logger().WithFields(fields).Info("nydusd started")
+
 	// Monitor nydusd's stdout/stderr and stop sandbox if nydusd quits
 	go func() {
 		scanner := bufio.NewScanner(stdout)
 		for scanner.Scan() {
 			nd.Logger().Info(scanner.Text())
 		}
-		nd.Logger().Info("nydusd quits")
+		nd.Logger().Warn("nydusd quits")
 		// Wait to release resources of nydusd process
 		_, err = cmd.Process.Wait()
 		if err != nil {
@@ -135,9 +140,24 @@ func (nd *nydusd) Start(ctx context.Context, onQuit onQuitFunc) (int, error) {
 			onQuit()
 		}
 	}()
-	if err := nd.setupShareDirFn(); err != nil {
-		return pid, err
+
+	nd.Logger().Info("waiting nydusd API server ready")
+	waitFn := nd.waitUntilNydusAPIServerReady
+	// waitFn may be set by a mock function for test
+	if nd.waitFn != nil {
+		waitFn = nd.waitFn
 	}
+	if err := waitFn(); err != nil {
+		return pid, errors.Wrap(err, "failed to wait nydusd API server ready")
+	}
+	nd.Logger().Info("nydusd API server ready, begin to setup share dir")
+
+	if err := nd.setupShareDirFn(); err != nil {
+		return pid, errors.Wrap(err, "failed to setup share dir for nydus")
+	}
+
+	nd.Logger().Info("nydusd setup share dir completed")
+
 	nd.pid = cmd.Process.Pid
 	return nd.pid, nil
 }
@@ -195,17 +215,39 @@ func (nd *nydusd) valid() error {
 }
 
 func (nd *nydusd) setupPassthroughFS() error {
+	nd.Logger().WithField("from", nd.sourcePath).
+		WithField("dest", sharedPathInGuest).Info("prepare mount passthroughfs")
+
 	nc, err := NewNydusClient(nd.apiSockPath)
 	if err != nil {
 		return err
 	}
-	nd.Logger().WithField("from", nd.sourcePath).
-		WithField("dest", sharedPathInGuest).Info("prepare mount passthroughfs")
 
 	mr := NewMountRequest(nydusPassthroughfs, nd.sourcePath, "")
 	return nc.Mount(sharedPathInGuest, mr)
 }
 
+func (nd *nydusd) waitUntilNydusAPIServerReady() error {
+	return retry.Do(func() error {
+		nc, err := NewNydusClient(nd.apiSockPath)
+		if err != nil {
+			return err
+		}
+
+		di, err := nc.CheckStatus()
+		if err != nil {
+			return err
+		}
+		if di.State == nydusdDaemonStateRunning {
+			return nil
+		}
+		return fmt.Errorf("Nydusd daemon is not running: %s", di.State)
+	},
+		retry.Attempts(20),
+		retry.LastErrorOnly(true),
+		retry.Delay(20*time.Millisecond))
+}
+
 func (nd *nydusd) Mount(opt MountOption) error {
 	nc, err := NewNydusClient(nd.apiSockPath)
 	if err != nil {

src/runtime/virtcontainers/nydusd_test.go

@@ -28,6 +28,7 @@ func TestNydusdStart(t *testing.T) {
 		debug           bool
 		extraArgs       []string
 		startFn         func(cmd *exec.Cmd) error
+		waitFn          func() error
 		setupShareDirFn func() error
 	}
 
@@ -46,6 +47,9 @@ func TestNydusdStart(t *testing.T) {
 			cmd.Process = &os.Process{}
 			return nil
 		},
+		waitFn: func() error {
+			return nil
+		},
 		setupShareDirFn: func() error { return nil },
 	}
 	SourcePathNoExist := validConfig
@@ -72,9 +76,11 @@ func TestNydusdStart(t *testing.T) {
 				debug:           tt.fields.debug,
 				pid:             tt.fields.pid,
 				startFn:         tt.fields.startFn,
+				waitFn:          tt.fields.waitFn,
 				setupShareDirFn: tt.fields.setupShareDirFn,
 			}
 			ctx := context.Background()
+
 			_, err := nd.Start(ctx, nil)
 			if (err != nil) != tt.wantErr {
 				t.Errorf("nydusd.Start() error = %v, wantErr %v", err, tt.wantErr)