Remove unnecessary job "initserverpidfile"

That job was a hacky solution to a real race condition. This removes the
hack without re-introducing the race.

Signed-off-by: Solomon Hykes <solomon@docker.com>

builtins/builtins.go

@@ -54,9 +54,6 @@ func remote(eng *engine.Engine) error {
 // These components should be broken off into plugins of their own.
 //
 func daemon(eng *engine.Engine) error {
-	if err := eng.Register("initserverpidfile", server.InitPidfile); err != nil {
-		return err
-	}
 	if err := eng.Register("initserver", server.InitServer); err != nil {
 		return err
 	}

docker/daemon.go

@@ -46,14 +46,6 @@ func mainDaemon() {
 		log.Fatal(err)
 	}
 
-	// handle the pidfile early. https://github.com/docker/docker/issues/6973
-	if len(*pidfile) > 0 {
-		job := eng.Job("initserverpidfile", *pidfile)
-		if err := job.Run(); err != nil {
-			log.Fatal(err)
-		}
-	}
-
 	// load the daemon in the background so we can immediately start
 	// the http api so that connections don't fail while the daemon
 	// is booting

server/init.go

@@ -5,12 +5,9 @@
 package server
 
 import (
-	"fmt"
-
 	"github.com/docker/docker/daemon"
 	"github.com/docker/docker/daemonconfig"
 	"github.com/docker/docker/engine"
-	"github.com/docker/docker/utils"
 )
 
 func (srv *Server) handlerWrap(h engine.Handler) engine.Handler {
@@ -24,17 +21,6 @@ func (srv *Server) handlerWrap(h engine.Handler) engine.Handler {
 	}
 }
 
-func InitPidfile(job *engine.Job) engine.Status {
-	if len(job.Args) == 0 {
-		return job.Error(fmt.Errorf("no pidfile provided to initialize"))
-	}
-	job.Logf("Creating pidfile")
-	if err := utils.CreatePidFile(job.Args[0]); err != nil {
-		return job.Error(err)
-	}
-	return engine.StatusOK
-}
-
 // jobInitApi runs the remote api server `srv` as a daemon,
 // Only one api server can run at the same time - this is enforced by a pidfile.
 // The signals SIGINT, SIGQUIT and SIGTERM are intercepted for cleanup.