Merge pull request #30223 from mlaventure/fix-logwatcher-deadlock

Close logwatcher on context cancellation
(cherry picked from commit 0566f3ffc4)

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

daemon/logger/jsonfilelog/read.go

@@ -137,7 +137,11 @@ func tailFile(f io.ReadSeeker, logWatcher *logger.LogWatcher, tail int, since ti
 		if !since.IsZero() && msg.Timestamp.Before(since) {
 			continue
 		}
-		logWatcher.Msg <- msg
+		select {
+		case <-logWatcher.WatchClose():
+			return
+		case logWatcher.Msg <- msg:
+		}
 	}
 }
 

daemon/logs.go

@@ -61,6 +61,18 @@ func (daemon *Daemon) ContainerLogs(ctx context.Context, containerName string, c
 		Follow: follow,
 	}
 	logs := logReader.ReadLogs(readConfig)
+	// Close logWatcher on exit
+	defer func() {
+		logs.Close()
+		if cLog != container.LogDriver {
+			// Since the logger isn't cached in the container, which
+			// occurs if it is running, it must get explicitly closed
+			// here to avoid leaking it and any file handles it has.
+			if err := cLog.Close(); err != nil {
+				logrus.Errorf("Error closing logger: %v", err)
+			}
+		}
+	}()
 
 	wf := ioutils.NewWriteFlusher(config.OutStream)
 	defer wf.Close()
@@ -81,19 +93,11 @@ func (daemon *Daemon) ContainerLogs(ctx context.Context, containerName string, c
 			logrus.Errorf("Error streaming logs: %v", err)
 			return nil
 		case <-ctx.Done():
-			logs.Close()
+			logrus.Debugf("logs: end stream, ctx is done: %v", ctx.Err())
 			return nil
 		case msg, ok := <-logs.Msg:
 			if !ok {
 				logrus.Debug("logs: end stream")
-				logs.Close()
-				if cLog != container.LogDriver {
-					// Since the logger isn't cached in the container, which occurs if it is running, it
-					// must get explicitly closed here to avoid leaking it and any file handles it has.
-					if err := cLog.Close(); err != nil {
-						logrus.Errorf("Error closing logger: %v", err)
-					}
-				}
 				return nil
 			}
 			logLine := msg.Line