Refactor daemon.attach()

Also makes streamConfig Pipe methods not return error, since there was
no error for them to be able to return anyway.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>

daemon/attach.go

@@ -8,7 +8,6 @@ import (
 
 	log "github.com/Sirupsen/logrus"
 	"github.com/docker/docker/engine"
-	"github.com/docker/docker/pkg/ioutils"
 	"github.com/docker/docker/pkg/jsonlog"
 	"github.com/docker/docker/pkg/promise"
 	"github.com/docker/docker/utils"
@@ -114,131 +113,97 @@ func (daemon *Daemon) ContainerAttach(job *engine.Job) engine.Status {
 func (daemon *Daemon) attach(streamConfig *StreamConfig, openStdin, stdinOnce, tty bool, stdin io.ReadCloser, stdout io.Writer, stderr io.Writer) chan error {
 	var (
 		cStdout, cStderr io.ReadCloser
+		cStdin           io.WriteCloser
 		nJobs            int
-		errors           = make(chan error, 3)
 	)
 
-	// Connect stdin of container to the http conn.
 	if stdin != nil && openStdin {
+		cStdin = streamConfig.StdinPipe()
 		nJobs++
-		// Get the stdin pipe.
-		if cStdin, err := streamConfig.StdinPipe(); err != nil {
-			errors <- err
-		} else {
-			go func() {
-				log.Debugf("attach: stdin: begin")
-				defer log.Debugf("attach: stdin: end")
-				if stdinOnce && !tty {
-					defer cStdin.Close()
-				} else {
-					// No matter what, when stdin is closed (io.Copy unblock), close stdout and stderr
-					defer func() {
-						if cStdout != nil {
-							cStdout.Close()
-						}
-						if cStderr != nil {
-							cStderr.Close()
-						}
-					}()
-				}
-				if tty {
-					_, err = utils.CopyEscapable(cStdin, stdin)
-				} else {
-					_, err = io.Copy(cStdin, stdin)
-
-				}
-				if err == io.ErrClosedPipe {
-					err = nil
-				}
-				if err != nil {
-					log.Errorf("attach: stdin: %s", err)
-				}
-				errors <- err
-			}()
-		}
 	}
+
 	if stdout != nil {
+		cStdout = streamConfig.StdoutPipe()
 		nJobs++
-		// Get a reader end of a pipe that is attached as stdout to the container.
-		if p, err := streamConfig.StdoutPipe(); err != nil {
-			errors <- err
-		} else {
-			cStdout = p
-			go func() {
-				log.Debugf("attach: stdout: begin")
-				defer log.Debugf("attach: stdout: end")
-				// If we are in StdinOnce mode, then close stdin
-				if stdinOnce && stdin != nil {
-					defer stdin.Close()
-				}
-				_, err := io.Copy(stdout, cStdout)
-				if err == io.ErrClosedPipe {
-					err = nil
-				}
-				if err != nil {
-					log.Errorf("attach: stdout: %s", err)
-				}
-				errors <- err
-			}()
-		}
-	} else {
-		// Point stdout of container to a no-op writer.
-		go func() {
-			if cStdout, err := streamConfig.StdoutPipe(); err != nil {
-				log.Errorf("attach: stdout pipe: %s", err)
-			} else {
-				io.Copy(&ioutils.NopWriter{}, cStdout)
-			}
-		}()
 	}
+
 	if stderr != nil {
+		cStderr = streamConfig.StderrPipe()
 		nJobs++
-		if p, err := streamConfig.StderrPipe(); err != nil {
-			errors <- err
-		} else {
-			cStderr = p
-			go func() {
-				log.Debugf("attach: stderr: begin")
-				defer log.Debugf("attach: stderr: end")
-				// If we are in StdinOnce mode, then close stdin
-				// Why are we closing stdin here and above while handling stdout?
-				if stdinOnce && stdin != nil {
-					defer stdin.Close()
-				}
-				_, err := io.Copy(stderr, cStderr)
-				if err == io.ErrClosedPipe {
-					err = nil
-				}
-				if err != nil {
-					log.Errorf("attach: stderr: %s", err)
+	}
+
+	errors := make(chan error, nJobs)
+
+	// Connect stdin of container to the http conn.
+	if stdin != nil && openStdin {
+		// Get the stdin pipe.
+		cStdin = streamConfig.StdinPipe()
+		go func() {
+			log.Debugf("attach: stdin: begin")
+			defer func() {
+				if stdinOnce && !tty {
+					defer cStdin.Close()
+				} else {
+					// No matter what, when stdin is closed (io.Copy unblock), close stdout and stderr
+					if cStdout != nil {
+						cStdout.Close()
+					}
+					if cStderr != nil {
+						cStderr.Close()
+					}
 				}
-				errors <- err
+				log.Debugf("attach: stdin: end")
 			}()
-		}
-	} else {
-		// Point stderr at a no-op writer.
-		go func() {
-			if cStderr, err := streamConfig.StderrPipe(); err != nil {
-				log.Errorf("attach: stdout pipe: %s", err)
+			var err error
+			if tty {
+				_, err = utils.CopyEscapable(cStdin, stdin)
 			} else {
-				io.Copy(&ioutils.NopWriter{}, cStderr)
+				_, err = io.Copy(cStdin, stdin)
+
 			}
+			if err == io.ErrClosedPipe {
+				err = nil
+			}
+			if err != nil {
+				log.Errorf("attach: stdin: %s", err)
+			}
+			errors <- err
 		}()
 	}
 
-	return promise.Go(func() error {
+	attachStream := func(name string, stream io.Writer, streamPipe io.ReadCloser) {
+		if stream == nil {
+			return
+		}
 		defer func() {
-			if cStdout != nil {
-				cStdout.Close()
-			}
-			if cStderr != nil {
-				cStderr.Close()
+			// Make sure stdin gets closed
+			if stdinOnce && cStdin != nil {
+				stdin.Close()
+				cStdin.Close()
 			}
+			streamPipe.Close()
 		}()
 
+		log.Debugf("attach: %s: begin", name)
+		defer log.Debugf("attach: %s: end", name)
+		_, err := io.Copy(stream, streamPipe)
+		if err == io.ErrClosedPipe {
+			err = nil
+		}
+		if err != nil {
+			log.Errorf("attach: %s: %v", name, err)
+		}
+		errors <- err
+	}
+
+	go attachStream("stdout", stdout, cStdout)
+	go attachStream("stderr", stderr, cStderr)
+
+	return promise.Go(func() error {
 		for i := 0; i < nJobs; i++ {
 			log.Debugf("attach: waiting for job %d/%d", i+1, nJobs)
-			if err := <-errors; err != nil {
+			err := <-errors
+			if err != nil {
 				log.Errorf("attach: job %d returned error %s, aborting all jobs", i+1, err)
 				return err
 			}

daemon/container.go

@@ -370,10 +370,7 @@ func (container *Container) Run() error {
 }
 
 func (container *Container) Output() (output []byte, err error) {
-	pipe, err := container.StdoutPipe()
-	if err != nil {
-		return nil, err
-	}
+	pipe := container.StdoutPipe()
 	defer pipe.Close()
 	if err := container.Start(); err != nil {
 		return nil, err
@@ -391,20 +388,20 @@ func (container *Container) Output() (output []byte, err error) {
 // copied and delivered to all StdoutPipe and StderrPipe consumers, using
 // a kind of "broadcaster".
 
-func (streamConfig *StreamConfig) StdinPipe() (io.WriteCloser, error) {
-	return streamConfig.stdinPipe, nil
+func (streamConfig *StreamConfig) StdinPipe() io.WriteCloser {
+	return streamConfig.stdinPipe
 }
 
-func (streamConfig *StreamConfig) StdoutPipe() (io.ReadCloser, error) {
+func (streamConfig *StreamConfig) StdoutPipe() io.ReadCloser {
 	reader, writer := io.Pipe()
 	streamConfig.stdout.AddWriter(writer, "")
-	return ioutils.NewBufReader(reader), nil
+	return ioutils.NewBufReader(reader)
 }
 
-func (streamConfig *StreamConfig) StderrPipe() (io.ReadCloser, error) {
+func (streamConfig *StreamConfig) StderrPipe() io.ReadCloser {
 	reader, writer := io.Pipe()
 	streamConfig.stderr.AddWriter(writer, "")
-	return ioutils.NewBufReader(reader), nil
+	return ioutils.NewBufReader(reader)
 }
 
 func (streamConfig *StreamConfig) StdoutLogPipe() io.ReadCloser {

integration/commands_test.go

@@ -412,7 +412,7 @@ func TestAttachDisconnect(t *testing.T) {
 	}
 
 	// Try to avoid the timeout in destroy. Best effort, don't check error
-	cStdin, _ := container.StdinPipe()
+	cStdin := container.StdinPipe()
 	cStdin.Close()
 	container.WaitStop(-1 * time.Second)
 }

integration/container_test.go

@@ -26,14 +26,8 @@ func TestRestartStdin(t *testing.T) {
 	}
 	defer daemon.Destroy(container)
 
-	stdin, err := container.StdinPipe()
-	if err != nil {
-		t.Fatal(err)
-	}
-	stdout, err := container.StdoutPipe()
-	if err != nil {
-		t.Fatal(err)
-	}
+	stdin := container.StdinPipe()
+	stdout := container.StdoutPipe()
 	if err := container.Start(); err != nil {
 		t.Fatal(err)
 	}
@@ -56,14 +50,8 @@ func TestRestartStdin(t *testing.T) {
 	}
 
 	// Restart and try again
-	stdin, err = container.StdinPipe()
-	if err != nil {
-		t.Fatal(err)
-	}
-	stdout, err = container.StdoutPipe()
-	if err != nil {
-		t.Fatal(err)
-	}
+	stdin = container.StdinPipe()
+	stdout = container.StdoutPipe()
 	if err := container.Start(); err != nil {
 		t.Fatal(err)
 	}
@@ -103,14 +91,8 @@ func TestStdin(t *testing.T) {
 	}
 	defer daemon.Destroy(container)
 
-	stdin, err := container.StdinPipe()
-	if err != nil {
-		t.Fatal(err)
-	}
-	stdout, err := container.StdoutPipe()
-	if err != nil {
-		t.Fatal(err)
-	}
+	stdin := container.StdinPipe()
+	stdout := container.StdoutPipe()
 	if err := container.Start(); err != nil {
 		t.Fatal(err)
 	}
@@ -149,14 +131,8 @@ func TestTty(t *testing.T) {
 	}
 	defer daemon.Destroy(container)
 
-	stdin, err := container.StdinPipe()
-	if err != nil {
-		t.Fatal(err)
-	}
-	stdout, err := container.StdoutPipe()
-	if err != nil {
-		t.Fatal(err)
-	}
+	stdin := container.StdinPipe()
+	stdout := container.StdoutPipe()
 	if err := container.Start(); err != nil {
 		t.Fatal(err)
 	}

integration/runtime_test.go

@@ -610,7 +610,7 @@ func TestRestore(t *testing.T) {
 	}
 
 	// Simulate a crash/manual quit of dockerd: process dies, states stays 'Running'
-	cStdin, _ := container2.StdinPipe()
+	cStdin := container2.StdinPipe()
 	cStdin.Close()
 	if _, err := container2.WaitStop(2 * time.Second); err != nil {
 		t.Fatal(err)

integration/utils_test.go

@@ -85,14 +85,8 @@ func containerFileExists(eng *engine.Engine, id, dir string, t Fataler) bool {
 
 func containerAttach(eng *engine.Engine, id string, t Fataler) (io.WriteCloser, io.ReadCloser) {
 	c := getContainer(eng, id, t)
-	i, err := c.StdinPipe()
-	if err != nil {
-		t.Fatal(err)
-	}
-	o, err := c.StdoutPipe()
-	if err != nil {
-		t.Fatal(err)
-	}
+	i := c.StdinPipe()
+	o := c.StdoutPipe()
 	return i, o
 }
 
@@ -292,10 +286,7 @@ func runContainer(eng *engine.Engine, r *daemon.Daemon, args []string, t *testin
 		return "", err
 	}
 	defer r.Destroy(container)
-	stdout, err := container.StdoutPipe()
-	if err != nil {
-		return "", err
-	}
+	stdout := container.StdoutPipe()
 	defer stdout.Close()
 
 	job := eng.Job("start", container.ID)