Changes to attach to enable per-stream attaching

This allows us to attach to attach to just stdout or stderr or
stdin, or any combination of these.

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>

Closes: #608
Approved by: baude

cmd/podman/attach.go

@@ -1,6 +1,8 @@
 package main
 
 import (
+	"os"
+
 	"github.com/pkg/errors"
 	"github.com/projectatomic/libpod/libpod"
 	"github.com/urfave/cli"
@@ -71,7 +73,12 @@ func attachCmd(c *cli.Context) error {
 		ProxySignals(ctr)
 	}
 
-	if err := ctr.Attach(c.Bool("no-stdin"), c.String("detach-keys")); err != nil {
+	inputStream := os.Stdin
+	if c.Bool("no-stdin") {
+		inputStream = nil
+	}
+
+	if err := attachCtr(ctr, os.Stdout, os.Stderr, inputStream, c.String("detach-keys")); err != nil {
 		return errors.Wrapf(err, "error attaching to container %s", ctr.ID())
 	}
 

cmd/podman/run.go

@@ -144,9 +144,42 @@ func runCmd(c *cli.Context) error {
 		return nil
 	}
 
-	// TODO: that "false" should probably be linked to -i
-	// Handle this when we split streams to allow attaching just stdin/out/err
-	attachChan, err := ctr.StartAndAttach(false, c.String("detach-keys"))
+	outputStream := os.Stdout
+	errorStream := os.Stderr
+	inputStream := os.Stdin
+
+	// If -i is not set, clear stdin
+	if !c.Bool("interactive") {
+		inputStream = nil
+	}
+
+	// If attach is set, clear stdin/stdout/stderr and only attach requested
+	if c.IsSet("attach") {
+		outputStream = nil
+		errorStream = nil
+		inputStream = nil
+
+		attachTo := c.StringSlice("attach")
+		for _, stream := range attachTo {
+			switch strings.ToLower(stream) {
+			case "stdout":
+				outputStream = os.Stdout
+			case "stderr":
+				errorStream = os.Stderr
+			case "stdin":
+				inputStream = os.Stdin
+			default:
+				return errors.Wrapf(libpod.ErrInvalidArg, "invalid stream %q for --attach - must be one of stdin, stdout, or stderr", stream)
+			}
+		}
+
+		// If --interactive is set, restore stdin
+		if c.Bool("interactive") {
+			inputStream = os.Stdin
+		}
+	}
+
+	attachChan, err := startAttachCtr(ctr, outputStream, errorStream, inputStream, c.String("detach-keys"))
 	if err != nil {
 		// This means the command did not exist
 		exitCode = 127

cmd/podman/start.go

@@ -95,7 +95,7 @@ func startCmd(c *cli.Context) error {
 		if c.Bool("interactive") && !ctr.Config().Stdin {
 			return errors.Errorf("the container was not created with the interactive option")
 		}
-		noStdIn := c.Bool("interactive")
+
 		tty, err := strconv.ParseBool(ctr.Spec().Annotations["io.kubernetes.cri-o.TTY"])
 		if err != nil {
 			return errors.Wrapf(err, "unable to parse annotations in %s", ctr.ID())
@@ -105,7 +105,12 @@ func startCmd(c *cli.Context) error {
 		// We only get a terminal session if both a tty was specified in the spec and
 		// -a on the command-line was given.
 		if attach && tty {
-			attachChan, err := ctr.StartAndAttach(noStdIn, c.String("detach-keys"))
+			inputStream := os.Stdin
+			if !c.Bool("interactive") {
+				inputStream = nil
+			}
+
+			attachChan, err := startAttachCtr(ctr, os.Stdout, os.Stderr, inputStream, c.String("detach-keys"))
 			if err != nil {
 				return errors.Wrapf(err, "unable to start container %s", ctr.ID())
 			}

cmd/podman/utils.go

@@ -1,9 +1,18 @@
 package main
 
 import (
+	"os"
+	gosignal "os/signal"
+
 	"github.com/containers/storage"
+	"github.com/docker/docker/pkg/signal"
+	"github.com/docker/docker/pkg/term"
+	"github.com/pkg/errors"
 	"github.com/projectatomic/libpod/libpod"
+	"github.com/sirupsen/logrus"
 	"github.com/urfave/cli"
+	"golang.org/x/crypto/ssh/terminal"
+	"k8s.io/client-go/tools/remotecommand"
 )
 
 // Generate a new libpod runtime configured by command line options
@@ -54,3 +63,81 @@ func getRuntime(c *cli.Context) (*libpod.Runtime, error) {
 
 	return libpod.NewRuntime(options...)
 }
+
+// Attach to a container
+func attachCtr(ctr *libpod.Container, stdout, stderr, stdin *os.File, detachKeys string) error {
+	resize := make(chan remotecommand.TerminalSize)
+
+	haveTerminal := terminal.IsTerminal(int(os.Stdin.Fd()))
+
+	// Check if we are attached to a terminal. If we are, generate resize
+	// events, and set the terminal to raw mode
+	if haveTerminal {
+		logrus.Debugf("Handling terminal attach")
+
+		resizeTty(resize)
+
+		oldTermState, err := term.SaveState(os.Stdin.Fd())
+		if err != nil {
+			return errors.Wrapf(err, "unable to save terminal state")
+		}
+
+		term.SetRawTerminal(os.Stdin.Fd())
+
+		defer term.RestoreTerminal(os.Stdin.Fd(), oldTermState)
+	}
+
+	return ctr.Attach(stdout, stderr, stdin, detachKeys, resize)
+}
+
+// Start and attach to a container
+func startAttachCtr(ctr *libpod.Container, stdout, stderr, stdin *os.File, detachKeys string) (<-chan error, error) {
+	resize := make(chan remotecommand.TerminalSize)
+
+	haveTerminal := terminal.IsTerminal(int(os.Stdin.Fd()))
+
+	// Check if we are attached to a terminal. If we are, generate resize
+	// events, and set the terminal to raw mode
+	if haveTerminal && ctr.Spec().Process.Terminal {
+		logrus.Debugf("Handling terminal attach")
+
+		resizeTty(resize)
+
+		oldTermState, err := term.SaveState(os.Stdin.Fd())
+		if err != nil {
+			return nil, errors.Wrapf(err, "unable to save terminal state")
+		}
+
+		term.SetRawTerminal(os.Stdin.Fd())
+
+		defer term.RestoreTerminal(os.Stdin.Fd(), oldTermState)
+	}
+
+	return ctr.StartAndAttach(stdout, stderr, stdin, detachKeys, resize)
+}
+
+// Helper for prepareAttach - set up a goroutine to generate terminal resize events
+func resizeTty(resize chan remotecommand.TerminalSize) {
+	sigchan := make(chan os.Signal, 1)
+	gosignal.Notify(sigchan, signal.SIGWINCH)
+	sendUpdate := func() {
+		winsize, err := term.GetWinsize(os.Stdin.Fd())
+		if err != nil {
+			logrus.Warnf("Could not get terminal size %v", err)
+			return
+		}
+		resize <- remotecommand.TerminalSize{
+			Width:  winsize.Width,
+			Height: winsize.Height,
+		}
+	}
+	go func() {
+		defer close(resize)
+		// Update the terminal size immediately without waiting
+		// for a SIGWINCH to get the correct initial size.
+		sendUpdate()
+		for range sigchan {
+			sendUpdate()
+		}
+	}()
+}