Merge pull request #306 from andrewhsu/health

[17.11] container: protect health monitor channel

components/engine/container/health.go

@@ -1,6 +1,8 @@
 package container
 
 import (
+	"sync"
+
 	"github.com/docker/docker/api/types"
 	"github.com/sirupsen/logrus"
 )
@@ -9,6 +11,7 @@ import (
 type Health struct {
 	types.Health
 	stop chan struct{} // Write struct{} to stop the monitor
+	mu   sync.Mutex
 }
 
 // String returns a human-readable description of the health-check state
@@ -26,9 +29,12 @@ func (s *Health) String() string {
 	}
 }
 
-// OpenMonitorChannel creates and returns a new monitor channel. If there already is one,
-// it returns nil.
+// OpenMonitorChannel creates and returns a new monitor channel. If there
+// already is one, it returns nil.
 func (s *Health) OpenMonitorChannel() chan struct{} {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
 	if s.stop == nil {
 		logrus.Debug("OpenMonitorChannel")
 		s.stop = make(chan struct{})
@@ -39,6 +45,9 @@ func (s *Health) OpenMonitorChannel() chan struct{} {
 
 // CloseMonitorChannel closes any existing monitor channel.
 func (s *Health) CloseMonitorChannel() {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
 	if s.stop != nil {
 		logrus.Debug("CloseMonitorChannel: waiting for probe to stop")
 		close(s.stop)