Fix update endpoint.

pkg/hypervisor/hypervisor.go

@@ -173,7 +173,7 @@ func (hv *Hypervisor) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 			r.Put("/visors/{pk}/routes/{rid}", hv.putRoute())
 			r.Delete("/visors/{pk}/routes/{rid}", hv.deleteRoute())
 			r.Get("/visors/{pk}/routegroups", hv.getRouteGroups())
-			r.Get("/visors/{pk}/restart", hv.restart())
+			r.Post("/visors/{pk}/restart", hv.restart())
 			r.Post("/visors/{pk}/exec", hv.exec())
 			r.Post("/visors/{pk}/update", hv.update())
 		})

pkg/restart/restart.go

@@ -37,7 +37,6 @@ type Context struct {
 // therefore calling CaptureContext immediately after starting executable is recommended.
 func CaptureContext() *Context {
 	cmd := exec.Command(os.Args[0], os.Args[1:]...) // nolint:gosec
-
 	cmd.Stdout = os.Stdout
 	cmd.Stdin = os.Stdin
 	cmd.Stderr = os.Stderr
@@ -70,24 +69,38 @@ func (c *Context) CmdPath() string {
 }
 
 // Start starts a new executable using Context.
-func (c *Context) Start() error {
+func (c *Context) Start() (err error) {
 	if !atomic.CompareAndSwapInt32(&c.isStarted, 0, 1) {
 		return ErrAlreadyStarted
 	}
 
 	errCh := c.startExec()
-
 	ticker := time.NewTicker(c.checkDelay)
-	defer ticker.Stop()
 
 	select {
-	case err := <-errCh:
+	case err = <-errCh:
 		c.errorLogger()("Failed to start new instance: %v", err)
-		return err
+
+		// Reset c.cmd on failure so it can be reused.
+		c.cmd = copyCmd(c.cmd)
+		atomic.StoreInt32(&c.isStarted, 0)
+
 	case <-ticker.C:
 		c.infoLogger()("New instance started successfully, exiting from the old one")
-		return nil
 	}
+
+	ticker.Stop()
+	return err
+}
+
+func copyCmd(oldCmd *exec.Cmd) *exec.Cmd {
+	newCmd := exec.Command(oldCmd.Path, oldCmd.Args...) // nolint:gosec
+	newCmd.Stdout = oldCmd.Stdout
+	newCmd.Stdin = oldCmd.Stdin
+	newCmd.Stderr = oldCmd.Stderr
+	newCmd.Env = oldCmd.Env
+
+	return newCmd
 }
 
 func (c *Context) startExec() chan error {

pkg/restart/restart_test.go

@@ -66,9 +66,9 @@ func TestContext_Start(t *testing.T) {
 		cc := CaptureContext()
 		assert.NotZero(t, len(cc.cmd.Args))
 
-		cmd := "touch"
-		path := "/tmp/test_start"
-		cc.cmd = exec.Command(cmd, path) // nolint:gosec
+		cmd := "sleep"
+		duration := "5"
+		cc.cmd = exec.Command(cmd, duration) // nolint:gosec
 		cc.appendDelay = false
 
 		errCh := make(chan error, 1)
@@ -82,8 +82,6 @@ func TestContext_Start(t *testing.T) {
 
 		assert.Contains(t, errors, ErrAlreadyStarted)
 		assert.Contains(t, errors, nil)
-
-		assert.NoError(t, os.Remove(path))
 	})
 }
 

pkg/util/updater/updater.go

@@ -57,7 +57,7 @@ type Updater struct {
 	log        *logging.Logger
 	restartCtx *restart.Context
 	appsPath   string
-	updating   uint32
+	updating   int32
 }
 
 // New returns a new Updater.
@@ -72,9 +72,10 @@ func New(log *logging.Logger, restartCtx *restart.Context, appsPath string) *Upd
 // Update performs an update operation.
 // NOTE: Update may call os.Exit.
 func (u *Updater) Update() (err error) {
-	if !atomic.CompareAndSwapUint32(&u.updating, 0, 1) {
+	if !atomic.CompareAndSwapInt32(&u.updating, 0, 1) {
 		return ErrAlreadyStarted
 	}
+	defer atomic.StoreInt32(&u.updating, 0)
 
 	u.log.Infof("Looking for updates")