Add stderr log ouput if in debug

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)

execdriver/native/driver.go

@@ -9,6 +9,7 @@ import (
 	"github.com/dotcloud/docker/pkg/libcontainer/apparmor"
 	"github.com/dotcloud/docker/pkg/libcontainer/nsinit"
 	"github.com/dotcloud/docker/pkg/system"
+	"io"
 	"io/ioutil"
 	"log"
 	"os"
@@ -28,8 +29,7 @@ func init() {
 	execdriver.RegisterInitFunc(DriverName, func(args *execdriver.InitArgs) error {
 		var (
 			container *libcontainer.Container
-			logger    = log.New(ioutil.Discard, "[nsinit] ", log.LstdFlags)
-			ns        = nsinit.NewNsInit(&nsinit.DefaultCommandFactory{}, &nsinit.DefaultStateWriter{args.Root}, logger)
+			ns        = nsinit.NewNsInit(&nsinit.DefaultCommandFactory{}, &nsinit.DefaultStateWriter{args.Root}, createLogger(""))
 		)
 		f, err := os.Open(filepath.Join(args.Root, "container.json"))
 		if err != nil {
@@ -87,9 +87,8 @@ func (d *driver) Run(c *execdriver.Command, pipes *execdriver.Pipes, startCallba
 			c:        c,
 			dsw:      &nsinit.DefaultStateWriter{filepath.Join(d.root, c.ID)},
 		}
-		logger = log.New(ioutil.Discard, "[nsinit] ", log.LstdFlags)
-		ns     = nsinit.NewNsInit(factory, stateWriter, logger)
-		args   = append([]string{c.Entrypoint}, c.Arguments...)
+		ns   = nsinit.NewNsInit(factory, stateWriter, createLogger(os.Getenv("DEBUG")))
+		args = append([]string{c.Entrypoint}, c.Arguments...)
 	)
 	if err := d.createContainerRoot(c.ID); err != nil {
 		return -1, err
@@ -254,3 +253,14 @@ func (d *dockerStateWriter) WritePid(pid int) error {
 func (d *dockerStateWriter) DeletePid() error {
 	return d.dsw.DeletePid()
 }
+
+func createLogger(debug string) *log.Logger {
+	var w io.Writer
+	// if we are in debug mode set the logger to stderr
+	if debug != "" {
+		w = os.Stderr
+	} else {
+		w = ioutil.Discard
+	}
+	return log.New(w, "[libcontainer] ", log.LstdFlags)
+}

pkg/libcontainer/nsinit/command.go

@@ -1,7 +1,6 @@
 package nsinit
 
 import (
-	"fmt"
 	"github.com/dotcloud/docker/pkg/libcontainer"
 	"github.com/dotcloud/docker/pkg/system"
 	"os"
@@ -26,7 +25,7 @@ func (c *DefaultCommandFactory) Create(container *libcontainer.Container, consol
 	// get our binary name from arg0 so we can always reexec ourself
 	command := exec.Command(os.Args[0], append([]string{
 		"-console", console,
-		"-pipe", fmt.Sprint(pipe.Fd()),
+		"-pipe", "3",
 		"-root", c.Root,
 		"init"}, args...)...)
 

pkg/libcontainer/nsinit/exec.go

@@ -26,6 +26,7 @@ func (ns *linuxNs) Exec(container *libcontainer.Container, term Terminal, args [
 	if err != nil {
 		return -1, err
 	}
+	ns.logger.Printf("created sync pipe parent fd %d child fd %d\n", syncPipe.parent.Fd(), syncPipe.child.Fd())
 
 	if container.Tty {
 		ns.logger.Println("creating master and console")

pkg/libcontainer/nsinit/init.go

@@ -24,6 +24,7 @@ func (ns *linuxNs) Init(container *libcontainer.Container, uncleanRootfs, consol
 	}
 
 	// We always read this as it is a way to sync with the parent as well
+	ns.logger.Printf("reading from sync pipe fd %d\n", syncPipe.child.Fd())
 	context, err := syncPipe.ReadFromParent()
 	if err != nil {
 		syncPipe.Close()
@@ -68,7 +69,7 @@ func (ns *linuxNs) Init(container *libcontainer.Container, uncleanRootfs, consol
 	}
 
 	if profile := container.Context["apparmor_profile"]; profile != "" {
-		ns.logger.Printf("setting apparmor prifile %s\n", profile)
+		ns.logger.Printf("setting apparmor profile %s\n", profile)
 		if err := apparmor.ApplyProfile(os.Getpid(), profile); err != nil {
 			return err
 		}