Merge pull request #14442 from cpuguy83/refactor_logdrvier_reader

Refactor log driver reader

api/client/logs.go

@@ -19,7 +19,7 @@ func (cli *DockerCli) CmdLogs(args ...string) error {
 	follow := cmd.Bool([]string{"f", "-follow"}, false, "Follow log output")
 	since := cmd.String([]string{"-since"}, "", "Show logs since timestamp")
 	times := cmd.Bool([]string{"t", "-timestamps"}, false, "Show timestamps")
-	tail := cmd.String([]string{"-tail"}, "latest", "Number of lines to show from the end of the logs")
+	tail := cmd.String([]string{"-tail"}, "all", "Number of lines to show from the end of the logs")
 	cmd.Require(flag.Exact, 1)
 
 	cmd.ParseFlags(args, true)

api/server/server.go

@@ -629,6 +629,17 @@ func (s *Server) getContainersLogs(version version.Version, w http.ResponseWrite
 		closeNotifier = notifier.CloseNotify()
 	}
 
+	c, err := s.daemon.Get(vars["name"])
+	if err != nil {
+		return err
+	}
+
+	outStream := ioutils.NewWriteFlusher(w)
+	// write an empty chunk of data (this is to ensure that the
+	// HTTP Response is sent immediatly, even if the container has
+	// not yet produced any data)
+	outStream.Write(nil)
+
 	logsConfig := &daemon.ContainerLogsConfig{
 		Follow:     boolValue(r, "follow"),
 		Timestamps: boolValue(r, "timestamps"),
@@ -636,11 +647,11 @@ func (s *Server) getContainersLogs(version version.Version, w http.ResponseWrite
 		Tail:       r.Form.Get("tail"),
 		UseStdout:  stdout,
 		UseStderr:  stderr,
-		OutStream:  ioutils.NewWriteFlusher(w),
+		OutStream:  outStream,
 		Stop:       closeNotifier,
 	}
 
-	if err := s.daemon.ContainerLogs(vars["name"], logsConfig); err != nil {
+	if err := s.daemon.ContainerLogs(c, logsConfig); err != nil {
 		fmt.Fprintf(w, "Error running logs job: %s\n", err)
 	}