Remote communication between engines using beam

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)

engine/remote.go

@@ -0,0 +1,109 @@
+package engine
+
+import (
+	"fmt"
+	"github.com/dotcloud/docker/pkg/beam"
+	"github.com/dotcloud/docker/pkg/beam/data"
+	"io"
+	"os"
+	"strconv"
+	"sync"
+)
+
+type Sender struct {
+	beam.Sender
+}
+
+func NewSender(s beam.Sender) *Sender {
+	return &Sender{s}
+}
+
+func (s *Sender) Install(eng *Engine) error {
+	// FIXME: this doesn't exist yet.
+	eng.RegisterCatchall(s.Handle)
+	return nil
+}
+
+func (s *Sender) Handle(job *Job) Status {
+	msg := data.Empty().Set("cmd", append([]string{job.Name}, job.Args...)...)
+	peer, err := beam.SendConn(s, msg.Bytes())
+	if err != nil {
+		return job.Errorf("beamsend: %v", err)
+	}
+	defer peer.Close()
+	var tasks sync.WaitGroup
+	defer tasks.Wait()
+	r := beam.NewRouter(nil)
+	r.NewRoute().KeyStartsWith("cmd", "log", "stdout").HasAttachment().Handler(func(p []byte, stdout *os.File) error {
+		tasks.Add(1)
+		io.Copy(job.Stdout, stdout)
+		tasks.Done()
+		return nil
+	})
+	r.NewRoute().KeyStartsWith("cmd", "log", "stderr").HasAttachment().Handler(func(p []byte, stderr *os.File) error {
+		tasks.Add(1)
+		io.Copy(job.Stderr, stderr)
+		tasks.Done()
+		return nil
+	})
+	var status int
+	r.NewRoute().KeyStartsWith("cmd", "status").Handler(func(p []byte, f *os.File) error {
+		cmd := data.Message(p).Get("cmd")
+		if len(cmd) != 3 {
+			return fmt.Errorf("usage: %s <0-127>", cmd[0])
+		}
+		s, err := strconv.ParseUint(cmd[2], 10, 8)
+		if err != nil {
+			return fmt.Errorf("usage: %s <0-127>", cmd[0])
+		}
+		status = int(s)
+		return nil
+
+	})
+	if _, err := beam.Copy(r, peer); err != nil {
+		return job.Errorf("%v", err)
+	}
+	return Status(status)
+}
+
+type Receiver struct {
+	*Engine
+	peer beam.Receiver
+}
+
+func NewReceiver(peer beam.Receiver) *Receiver {
+	return &Receiver{Engine: New(), peer: peer}
+}
+
+func (rcv *Receiver) Run() error {
+	r := beam.NewRouter(nil)
+	r.NewRoute().KeyExists("cmd").Handler(func(p []byte, f *os.File) error {
+		// Use the attachment as a beam return channel
+		peer, err := beam.FileConn(f)
+		if err != nil {
+			f.Close()
+			return err
+		}
+		cmd := data.Message(p).Get("cmd")
+		job := rcv.Engine.Job(cmd[0], cmd[1:]...)
+		stdout, err := beam.SendPipe(peer, data.Empty().Set("cmd", "log", "stdout").Bytes())
+		if err != nil {
+			return err
+		}
+		job.Stdout.Add(stdout)
+		stderr, err := beam.SendPipe(peer, data.Empty().Set("cmd", "log", "stderr").Bytes())
+		if err != nil {
+			return err
+		}
+		job.Stderr.Add(stderr)
+		// ignore error because we pass the raw status
+		job.Run()
+		err = peer.Send(data.Empty().Set("cmd", "status", fmt.Sprintf("%d", job.status)).Bytes(), nil)
+		if err != nil {
+			return err
+		}
+		return nil
+	})
+	_, err := beam.Copy(r, rcv.peer)
+	return err
+}

engine/remote_test.go

@@ -0,0 +1,3 @@
+package engine
+
+import ()