server: fsnotify on hooks

Signed-off-by: Antonio Murdaca <runcom@redhat.com>

cmd/crio/main.go

@@ -485,6 +485,9 @@ func main() {
 		go func() {
 			service.StartExitMonitor()
 		}()
+		go func() {
+			service.StartHooksMonitor()
+		}()
 
 		m := cmux.New(lis)
 		grpcL := m.Match(cmux.HTTP2HeaderField("content-type", "application/grpc"))
@@ -527,7 +530,7 @@ func main() {
 		<-streamServerCloseCh
 		logrus.Debug("closed stream server")
 		<-serverMonitorsCh
-		logrus.Debug("closed exit monitor")
+		logrus.Debug("closed monitors")
 		<-serverCloseCh
 		logrus.Debug("closed main server")
 

lib/container_server.go

@@ -39,6 +39,7 @@ type ContainerServer struct {
 	podNameIndex         *registrar.Registrar
 	podIDIndex           *truncindex.TruncIndex
 	hooks                map[string]HookParams
+	hooksLock            sync.Mutex
 
 	imageContext *types.SystemContext
 	stateLock    sync.Locker
@@ -53,7 +54,41 @@ func (c *ContainerServer) Runtime() *oci.Runtime {
 
 // Hooks returns the oci hooks for the ContainerServer
 func (c *ContainerServer) Hooks() map[string]HookParams {
-	return c.hooks
+	hooks := map[string]HookParams{}
+	c.hooksLock.Lock()
+	defer c.hooksLock.Unlock()
+	for key, h := range c.hooks {
+		hooks[key] = h
+	}
+	return hooks
+}
+
+// RemoveHook removes an hook by name
+func (c *ContainerServer) RemoveHook(hook string) {
+	c.hooksLock.Lock()
+	defer c.hooksLock.Unlock()
+	if _, ok := c.hooks[hook]; ok {
+		delete(c.hooks, hook)
+	}
+}
+
+// AddHook adds an hook by hook's path
+func (c *ContainerServer) AddHook(hookPath string) {
+	c.hooksLock.Lock()
+	defer c.hooksLock.Unlock()
+	hook, err := readHook(hookPath)
+	if err != nil {
+		logrus.Debugf("error while reading hook %s", hookPath)
+		return
+	}
+	for key, h := range c.hooks {
+		// hook.Hook can only be defined in one hook file, unless it has the
+		// same name in the override path.
+		if hook.Hook == h.Hook && key != filepath.Base(hookPath) {
+			logrus.Debugf("duplicate path,  hook %q from %q already defined in %q", hook.Hook, c.config.HooksDirPath, key)
+		}
+	}
+	c.hooks[filepath.Base(hookPath)] = hook
 }
 
 // Store returns the Store for the ContainerServer
@@ -153,6 +188,7 @@ func New(config *Config) (*ContainerServer, error) {
 			}
 		}
 	}
+	logrus.Debugf("hooks %+v", hooks)
 
 	return &ContainerServer{
 		runtime:              runtime,

lib/hooks.go

@@ -30,9 +30,16 @@ type HookParams struct {
 	Arguments     []string `json:"arguments"`
 }
 
+var (
+	errNotJSON = errors.New("hook file isn't a JSON")
+)
+
 // readHook reads hooks json files, verifies it and returns the json config
 func readHook(hookPath string) (HookParams, error) {
 	var hook HookParams
+	if !strings.HasSuffix(hookPath, ".json") {
+		return hook, errNotJSON
+	}
 	raw, err := ioutil.ReadFile(hookPath)
 	if err != nil {
 		return hook, errors.Wrapf(err, "error Reading hook %q", hookPath)
@@ -83,11 +90,11 @@ func readHooks(hooksPath string, hooks map[string]HookParams) error {
 	}
 
 	for _, file := range files {
-		if !strings.HasSuffix(file.Name(), ".json") {
-			continue
-		}
 		hook, err := readHook(filepath.Join(hooksPath, file.Name()))
 		if err != nil {
+			if err == errNotJSON {
+				continue
+			}
 			return err
 		}
 		for key, h := range hooks {

server/server.go

@@ -365,6 +365,46 @@ func (s *Server) MonitorsCloseChan() chan struct{} {
 	return s.monitorsChan
 }
 
+// StartHooksMonitor starts a goroutine to dynamically add hooks at runtime
+func (s *Server) StartHooksMonitor() {
+	watcher, err := fsnotify.NewWatcher()
+	if err != nil {
+		logrus.Fatalf("Failed to create new watch: %v", err)
+	}
+	defer watcher.Close()
+
+	done := make(chan struct{})
+	go func() {
+		for {
+			select {
+			case event := <-watcher.Events:
+				logrus.Debugf("event: %v", event)
+				if event.Op&fsnotify.Remove == fsnotify.Remove {
+					logrus.Debugf("removing hook %s", event.Name)
+					s.ContainerServer.RemoveHook(filepath.Base(event.Name))
+				}
+				if event.Op&fsnotify.Create == fsnotify.Create || event.Op&fsnotify.Write == fsnotify.Write {
+					logrus.Debugf("adding hook %s", event.Name)
+					s.ContainerServer.AddHook(event.Name)
+				}
+			case err := <-watcher.Errors:
+				logrus.Debugf("watch error: %v", err)
+				close(done)
+				return
+			case <-s.monitorsChan:
+				logrus.Debug("closing hooks monitor...")
+				close(done)
+				return
+			}
+		}
+	}()
+	if err := watcher.Add(s.config.HooksDirPath); err != nil {
+		logrus.Errorf("watcher.Add(%q) failed: %s", s.config.HooksDirPath, err)
+		close(done)
+	}
+	<-done
+}
+
 // StartExitMonitor start a routine that monitors container exits
 // and updates the container status
 func (s *Server) StartExitMonitor() {