Improve logging for nsinit

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

libcontainer/nsinit/nsinit.go

@@ -0,0 +1,29 @@
+package nsinit
+
+import (
+	"github.com/dotcloud/docker/pkg/libcontainer"
+	"log"
+)
+
+type NsInit interface {
+	Exec(container *libcontainer.Container, term Terminal, args []string) (int, error)
+	ExecIn(container *libcontainer.Container, nspid int, args []string) (int, error)
+	Init(container *libcontainer.Container, uncleanRootfs, console string, syncPipe *SyncPipe, args []string) error
+}
+
+type linuxNs struct {
+	root           string
+	logFile        string
+	logger         *log.Logger
+	commandFactory CommandFactory
+	stateWriter    StateWriter
+}
+
+func NewNsInit(logger *log.Logger, logFile string, command CommandFactory, state StateWriter) NsInit {
+	return &linuxNs{
+		logger:         logger,
+		commandFactory: command,
+		stateWriter:    state,
+		logFile:        logFile,
+	}
+}