bugfix: events api is a long connection, the connection may be recycl…

…ed if it keeps idle too long

Signed-off-by: Michael Wan <zirenwan@gmail.com>

apis/server/router.go

@@ -28,7 +28,7 @@ func initRoute(s *Server) http.Handler {
 	s.addRoute(r, http.MethodGet, "/info", s.info)
 	s.addRoute(r, http.MethodGet, "/version", s.version)
 	s.addRoute(r, http.MethodPost, "/auth", s.auth)
-	s.addRoute(r, http.MethodGet, "/events", s.events)
+	s.addRoute(r, http.MethodGet, "/events", withCancelHandler(s.events))
 
 	// daemon, we still list this API into system manager.
 	s.addRoute(r, http.MethodPost, "/daemon/update", s.updateDaemon)

apis/server/system_bridge.go

@@ -14,6 +14,7 @@ import (
 
 	"github.com/docker/docker/pkg/ioutils"
 	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
 )
 
 func (s *Server) ping(context context.Context, rw http.ResponseWriter, req *http.Request) (err error) {
@@ -69,9 +70,6 @@ func (s *Server) auth(ctx context.Context, rw http.ResponseWriter, req *http.Req
 }
 
 func (s *Server) events(ctx context.Context, rw http.ResponseWriter, req *http.Request) (err error) {
-	ctx, cancel := context.WithCancel(ctx)
-	defer cancel()
-
 	rw.Header().Set("Content-Type", "application/json")
 	output := ioutils.NewWriteFlusher(rw)
 	defer output.Close()
@@ -123,11 +121,18 @@ func (s *Server) events(ctx context.Context, rw http.ResponseWriter, req *http.R
 		return nil
 	}
 
+	// Notes(ziren): The pouchd http server set some http timeout parameters (see pouch/apis/server/server.go),
+	// that may cause long idle connections been recycled. So, creating a tick here to keep the
+	// event api alive. set the ticker to 8s because of the IdleTimeout of http server is 10s.
+	ticker := time.NewTicker(time.Second * 8)
+	defer ticker.Stop()
+
 	// start subscribe new pouchd events
 	for {
 		select {
 		case ev := <-eventq:
 			if err := enc.Encode(ev); err != nil {
+				logrus.Errorf("encode events got an error: %v", err)
 				return err
 			}
 		case err := <-errq:
@@ -137,6 +142,15 @@ func (s *Server) events(ctx context.Context, rw http.ResponseWriter, req *http.R
 			return nil
 		case <-timeout:
 			return nil
+		case <-ticker.C:
+			emptyEvents := &types.EventsMessage{}
+			if err := enc.Encode(emptyEvents); err != nil {
+				logrus.Errorf("encode empty events got an error: %v", err)
+				return err
+			}
+		case <-ctx.Done():
+			logrus.Debug("client context is cancelled, stop sending events")
+			return nil
 		}
 	}
 }

cli/events.go

@@ -94,15 +94,24 @@ type eventProcessor func(event types.EventsMessage, err error) error
 // Each output includes the event type, actor id, name and action.
 // Actor attributes are printed at the end if the actor has any.
 func printOutput(event types.EventsMessage, output io.Writer) {
+	// skip empty event message
+	if event == (types.EventsMessage{}) {
+		return
+	}
+
 	if event.TimeNano != 0 {
 		fmt.Fprintf(output, "%s ", time.Unix(0, event.TimeNano).Format(utils.RFC3339NanoFixed))
 	} else if event.Time != 0 {
 		fmt.Fprintf(output, "%s ", time.Unix(event.Time, 0).Format(utils.RFC3339NanoFixed))
 	}
 
-	fmt.Fprintf(output, "%s %s %s", event.Type, event.Action, event.Actor.ID)
+	id := ""
+	if event.Actor != nil {
+		id = event.Actor.ID
+	}
+	fmt.Fprintf(output, "%s %s %s", event.Type, event.Action, id)
 
-	if len(event.Actor.Attributes) > 0 {
+	if event.Actor != nil && len(event.Actor.Attributes) > 0 {
 		var attrs []string
 		var keys []string
 		for k := range event.Actor.Attributes {