1) actually launch application

2) improved signaling from oz-init to oz-daemon when ready

oz-daemon/launch.go

@@ -11,6 +11,7 @@ import (
 	"os/exec"
 	"os/user"
 	"path"
+	"sync"
 	"syscall"
 )
 
@@ -27,6 +28,7 @@ type Sandbox struct {
 	stderr  io.ReadCloser
 	addr    string
 	xpra    *xpra.Xpra
+	ready   sync.WaitGroup
 }
 
 /*
@@ -95,7 +97,14 @@ func (d *daemonState) launch(p *oz.Profile, uid, gid uint32) (*Sandbox, error) {
 		addr:    path.Join(fs.Root(), "tmp", "oz-init-control"),
 		stderr:  pp,
 	}
+	sbox.ready.Add(1)
 	go sbox.logMessages()
+	if sbox.profile.XServer.Enabled {
+		go func() {
+			sbox.ready.Wait()
+			go sbox.startXpraClient()
+		}()
+	}
 	d.nextSboxId += 1
 	d.sandboxes = append(d.sandboxes, sbox)
 	return sbox, nil
@@ -115,11 +124,13 @@ func (sbox *Sandbox) remove() {
 
 func (sbox *Sandbox) logMessages() {
 	scanner := bufio.NewScanner(sbox.stderr)
+	seenOk := false
 	for scanner.Scan() {
 		line := scanner.Text()
-		if line == "XPRA READY" {
+		if line == "OK" && !seenOk {
-			sbox.daemon.log.Info("Xpra server is ready for connection")
+			sbox.daemon.log.Info("oz-init (%s) is ready", sbox.profile.Name)
-			go sbox.startXpraClient()
+			seenOk = true
+			sbox.ready.Done()
 		} else if len(line) > 1 {
 			sbox.logLine(line)
 		}

oz-init/init.go

@@ -15,6 +15,7 @@ import (
 	"os/user"
 	"strconv"
 	"strings"
+	"sync"
 	"syscall"
 )
 
@@ -29,6 +30,7 @@ type initState struct {
 	user      *user.User
 	display   int
 	fs        *fs.Filesystem
+	xpraReady sync.WaitGroup
 }
 
 // By convention oz-init writes log messages to stderr with a single character
@@ -121,15 +123,18 @@ func (st *initState) runInit() {
 		st.log.Error("Error: setting up filesystem failed: %v\n", err)
 		os.Exit(1)
 	}
+	oz.ReapChildProcs(st.log, st.handleChildExit)
+
 	if st.profile.XServer.Enabled {
 		if st.display == 0 {
 			st.log.Error("Cannot start xpra because no display number was passed to oz-init")
 			os.Exit(1)
 		}
+		st.xpraReady.Add(1)
 		st.startXpraServer()
 	}
-
+	st.xpraReady.Wait()
-	oz.ReapChildProcs(st.log, st.handleChildExit)
+	st.launchApplication()
 
 	s, err := ipc.NewServer(SocketAddress, messageFactory, st.log,
 		handlePing,
@@ -142,6 +147,7 @@ func (st *initState) runInit() {
 	if err := os.Chown(SocketAddress, st.uid, st.gid); err != nil {
 		st.log.Warning("Failed to chown oz-init control socket: %v", err)
 	}
+	os.Stderr.WriteString("OK\n")
 
 	if err := s.Run(); err != nil {
 		st.log.Warning("MsgServer.Run() return err: %v", err)
@@ -178,11 +184,13 @@ func (st *initState) startXpraServer() {
 
 func (st *initState) readXpraOutput(r io.ReadCloser) {
 	sc := bufio.NewScanner(r)
+	seenReady := false
 	for sc.Scan() {
 		line := sc.Text()
 		if len(line) > 0 {
-			if strings.Contains(line, "xpra is ready.") {
+			if strings.Contains(line, "xpra is ready.") && !seenReady {
-				os.Stderr.WriteString("XPRA READY\n")
+				seenReady = true
+				st.xpraReady.Done()
 				if !st.config.LogXpra {
 					r.Close()
 					return
@@ -195,6 +203,42 @@ func (st *initState) readXpraOutput(r io.ReadCloser) {
 	}
 }
 
+func (st *initState) launchApplication() {
+	cmd := exec.Command(st.profile.Path)
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		st.log.Warning("Failed to create stdout pipe: %v", err)
+		return
+	}
+	stderr, err := cmd.StderrPipe()
+	if err != nil {
+		st.log.Warning("Failed to create stderr pipe: %v", err)
+		return
+	}
+	cmd.SysProcAttr = &syscall.SysProcAttr{}
+	cmd.SysProcAttr.Credential = &syscall.Credential{
+		Uid: uint32(st.uid),
+		Gid: uint32(st.gid),
+	}
+	cmd.Env = []string{
+		fmt.Sprintf("DISPLAY=:%d", st.display),
+	}
+	if err := cmd.Start(); err != nil {
+		st.log.Warning("Failed to start application (%s): %v", st.profile.Path, err)
+		return
+	}
+	go st.readApplicationOutput(stdout, "stdout")
+	go st.readApplicationOutput(stderr, "stderr")
+}
+
+func (st *initState) readApplicationOutput(r io.ReadCloser, label string) {
+	sc := bufio.NewScanner(r)
+	for sc.Scan() {
+		line := sc.Text()
+		st.log.Debug("(%s) %s", label, line)
+	}
+}
+
 func loadProfile(dir, name string) (*oz.Profile, error) {
 	ps, err := oz.LoadProfiles(dir)
 	if err != nil {