beam/examples/beamsh: use 'log' command to pass stdout

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

beam/examples/beamsh/beamsh.go

@@ -11,6 +11,8 @@ import (
 	"net"
 	"bytes"
 	"path"
+	"bufio"
+	"strconv"
 )
 
 func main() {
@@ -32,20 +34,25 @@ func main() {
 		if err != nil {
 			Fatal(err)
 		}
-		// Synchronize on the job handler
+		Serve(job)
-		for {
-			_, _, err := beam.Receive(job)
-			if err == io.EOF {
-				break
-			} else if err != nil {
-				Fatalf("error reading from job handler: %#v\n", err)
-			}
-		}
 		Logf("[%s] done\n", strings.Join(cmd.Args, " "))
 	}
 	client.Close()
 }
 
+func parseMsgPayload(payload []byte) ([]string, error) {
+	// FIXME: send structured message instead of a text script
+	cmds, err := dockerscript.Parse(bytes.NewReader(payload))
+	if err != nil {
+		return nil, err
+	}
+	if len(cmds) == 0 {
+		return nil, fmt.Errorf("empty command")
+	}
+	// We don't care about multiple commands or children
+	return cmds[0].Args, nil
+}
+
 func CmdCat(args []string, f *os.File) {
 	for _, name := range args[1:] {
 		f, err := os.Open(name)
@@ -58,17 +65,55 @@ func CmdCat(args []string, f *os.File) {
 }
 
 func CmdEcho(args []string, f *os.File) {
-	fmt.Println(strings.Join(args[1:], " "))
+	resp, err := beam.FdConn(int(f.Fd()))
+	if err != nil {
+		return
+	}
+	r, w, err := os.Pipe()
+	if err != nil {
+		return
+	}
+	if err := beam.Send(resp, []byte("log stdout"), r); err != nil {
+		return
+	}
+	fmt.Fprintln(w, strings.Join(args[1:], " "))
+	fmt.Printf("waiting 5 seconds...\n")
+	w.Close()
 }
 
-func CmdDie(args []string, f *os.File) {
+func CmdExit(args []string, f *os.File) {
-	Fatal(strings.Join(args[1:], " "))
+	var status int
+	if len(args) > 1 {
+		val, err := strconv.ParseInt(args[1], 10, 32)
+		if err == nil {
+			status = int(val)
+		}
+	}
+	os.Exit(status)
+}
+
+func CmdLog(args []string, f *os.File) {
+	name := args[1]
+	input := bufio.NewScanner(f)
+	for input.Scan() {
+		line := input.Text()
+		if len(line) > 0 {
+			fmt.Printf("[%s] %s\n", name, line)
+		}
+		if err := input.Err(); err != nil {
+			fmt.Printf("[%s:%s]\n", name, err)
+			break
+		}
+	}
 }
 
 func Serve(endpoint *net.UnixConn) error {
+	Logf("[Serve]\n")
+	defer Logf("[Serve] done\n")
 	var tasks sync.WaitGroup
 	defer tasks.Wait()
 	for {
+		Logf("[Serve] waiting for next message...\n")
 		payload, attachment, err := beam.Receive(endpoint)
 		if err != nil {
 			return err
@@ -76,13 +121,11 @@ func Serve(endpoint *net.UnixConn) error {
 		tasks.Add(1)
 		go func(payload []byte, attachment *os.File) {
 			defer tasks.Done()
-			defer func() {
 			if attachment != nil {
+				defer fmt.Printf("closing request attachment %d\n", attachment.Fd())
 				attachment.Close()
 			}
-			}()
+			args, err := parseMsgPayload(payload)
-			// FIXME: send structured message instead of a text script
-			cmds, err := dockerscript.Parse(bytes.NewReader(payload))
 			if err != nil {
 				Logf("error parsing beam message: %s\n", err)
 				if attachment != nil {
@@ -90,18 +133,15 @@ func Serve(endpoint *net.UnixConn) error {
 				}
 				return
 			}
-			if len(cmds) == 0 {
-				Logf("ignoring empty command\n", err)
-			}
-			// We don't care about multiple commands or children
-			args := cmds[0].Args
 			Logf("beam message: %v\n", args)
-			if args[0] == "die" {
+			if args[0] == "exit" {
-				CmdDie(args, attachment)
+				CmdExit(args, attachment)
 			} else if args[0] == "cat" {
 				CmdCat(args, attachment)
 			} else if args[0] == "echo" {
 				CmdEcho(args, attachment)
+			} else if args[0] == "log" {
+				CmdLog(args, attachment)
 			}
 		}(payload, attachment)
 	}