Merge pull request #473 from mrunalp/port_forward

Add support for port forwarding

server/container_portforward.go

@@ -1,11 +1,86 @@
 package server
 
 import (
+	"bytes"
+	"fmt"
+	"io"
+	"os/exec"
+	"strings"
+
+	"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"
 )
 
 // PortForward prepares a streaming endpoint to forward ports from a PodSandbox.
 func (s *Server) PortForward(ctx context.Context, req *pb.PortForwardRequest) (*pb.PortForwardResponse, error) {
-	return nil, nil
+	logrus.Debugf("PortForwardRequest %+v", req)
+
+	resp, err := s.GetPortForward(req)
+
+	if err != nil {
+		return nil, fmt.Errorf("unable to prepare portforward endpoint")
+	}
+
+	return resp, nil
+}
+
+func (ss streamService) PortForward(podInfraContainerID string, port int32, stream io.ReadWriteCloser) error {
+	c := ss.runtimeServer.state.containers.Get(podInfraContainerID)
+
+	if err := ss.runtimeServer.runtime.UpdateStatus(c); err != nil {
+		return err
+	}
+
+	cState := ss.runtimeServer.runtime.ContainerStatus(c)
+	if !(cState.Status == oci.ContainerStateRunning || cState.Status == oci.ContainerStateCreated) {
+		return fmt.Errorf("container is not created or running")
+	}
+
+	containerPid := cState.Pid
+	socatPath, lookupErr := exec.LookPath("socat")
+	if lookupErr != nil {
+		return fmt.Errorf("unable to do port forwarding: socat not found")
+	}
+
+	args := []string{"-t", fmt.Sprintf("%d", containerPid), "-n", socatPath, "-", fmt.Sprintf("TCP4:localhost:%d", port)}
+
+	nsenterPath, lookupErr := exec.LookPath("nsenter")
+	if lookupErr != nil {
+		return fmt.Errorf("unable to do port forwarding: nsenter not found")
+	}
+
+	commandString := fmt.Sprintf("%s %s", nsenterPath, strings.Join(args, " "))
+	logrus.Debugf("executing port forwarding command: %s", commandString)
+
+	command := exec.Command(nsenterPath, args...)
+	command.Stdout = stream
+
+	stderr := new(bytes.Buffer)
+	command.Stderr = stderr
+
+	// If we use Stdin, command.Run() won't return until the goroutine that's copying
+	// from stream finishes. Unfortunately, if you have a client like telnet connected
+	// via port forwarding, as long as the user's telnet client is connected to the user's
+	// local listener that port forwarding sets up, the telnet session never exits. This
+	// means that even if socat has finished running, command.Run() won't ever return
+	// (because the client still has the connection and stream open).
+	//
+	// The work around is to use StdinPipe(), as Wait() (called by Run()) closes the pipe
+	// when the command (socat) exits.
+	inPipe, err := command.StdinPipe()
+	if err != nil {
+		return fmt.Errorf("unable to do port forwarding: error creating stdin pipe: %v", err)
+	}
+	go func() {
+		io.Copy(inPipe, stream)
+		inPipe.Close()
+	}()
+
+	if err := command.Run(); err != nil {
+		return fmt.Errorf("%v: %s", err, stderr.String())
+	}
+
+	return nil
 }