Fix terminal resize handling so kubectl exec -i -t sh works

Signed-off-by: Mrunal Patel <mpatel@redhat.com>

server/container_exec.go

@@ -3,12 +3,15 @@ package server
 import (
 	"fmt"
 	"io"
+	"os"
 	"os/exec"
 
 	"github.com/Sirupsen/logrus"
 	"github.com/kubernetes-incubator/cri-o/oci"
 	"golang.org/x/net/context"
 	pb "k8s.io/kubernetes/pkg/kubelet/api/v1alpha1/runtime"
+	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
+	utilexec "k8s.io/kubernetes/pkg/util/exec"
 	"k8s.io/kubernetes/pkg/util/term"
 )
 
@@ -25,8 +28,8 @@ func (s *Server) Exec(ctx context.Context, req *pb.ExecRequest) (*pb.ExecRespons
 }
 
 // Exec endpoint for streaming.Runtime
-func (ss streamService) Exec(containerID string, cmd []string, in io.Reader, out, errOut io.WriteCloser, tty bool, resize <-chan term.Size) error {
-	fmt.Println(containerID, cmd, in, out, errOut, tty, resize)
+func (ss streamService) Exec(containerID string, cmd []string, stdin io.Reader, stdout, stderr io.WriteCloser, tty bool, resize <-chan term.Size) error {
+	fmt.Println(containerID, cmd, stdin, stdout, stderr, tty, resize)
 	c := ss.runtimeServer.state.containers.Get(containerID)
 
 	if err := ss.runtimeServer.runtime.UpdateStatus(c); err != nil {
@@ -38,16 +41,63 @@ func (ss streamService) Exec(containerID string, cmd []string, in io.Reader, out
 		return fmt.Errorf("container is not created or running")
 	}
 
-	args := []string{"exec", c.Name()}                                 // exec ctr
-	args = append(args, cmd...)                                        // exec ctr cmd
-	execCmd := exec.Command(ss.runtimeServer.runtime.Path(c), args...) // runc exec ctr cmd
-	execCmd.Stdin = in
-	execCmd.Stdout = out
-	execCmd.Stderr = errOut
+	args := []string{"exec"}
+	if tty {
+		args = append(args, "-t")
+	}
+	args = append(args, c.Name())
+	args = append(args, cmd...)
+	execCmd := exec.Command(ss.runtimeServer.runtime.Path(c), args...)
+	var cmdErr error
+	if tty {
+		p, err := kubecontainer.StartPty(execCmd)
+		if err != nil {
+			return err
+		}
+		defer p.Close()
 
-	if err := execCmd.Run(); err != nil {
-		return err
+		// make sure to close the stdout stream
+		defer stdout.Close()
+
+		kubecontainer.HandleResizing(resize, func(size term.Size) {
+			term.SetSize(p.Fd(), size)
+		})
+
+		if stdin != nil {
+			go io.Copy(p, stdin)
+		}
+
+		if stdout != nil {
+			go io.Copy(stdout, p)
+		}
+
+		cmdErr = execCmd.Wait()
+	} else {
+		if stdin != nil {
+			// Use an os.Pipe here as it returns true *os.File objects.
+			// This way, if you run 'kubectl exec <pod> -i bash' (no tty) and type 'exit',
+			// the call below to execCmd.Run() can unblock because its Stdin is the read half
+			// of the pipe.
+			r, w, err := os.Pipe()
+			if err != nil {
+				return err
+			}
+			go io.Copy(w, stdin)
+
+			execCmd.Stdin = r
+		}
+		if stdout != nil {
+			execCmd.Stdout = stdout
+		}
+		if stderr != nil {
+			execCmd.Stderr = stderr
+		}
+
+		cmdErr = execCmd.Run()
 	}
 
-	return nil
+	if exitErr, ok := cmdErr.(*exec.ExitError); ok {
+		return &utilexec.ExitErrorWrapper{ExitError: exitErr}
+	}
+	return cmdErr
 }