make listen buffer optional

Docker-DCO-1.1-Signed-off-by: Victor Vieux <vieux@docker.com> (github: vieux)
Upstream-commit: f3736265fdddef9e9a9ab588906eeb7abe8a0cf6
Component: engine

components/engine/api/server/server.go

@@ -1193,6 +1193,7 @@ func changeGroup(addr string, nameOrGid string) error {
 // ListenAndServe sets up the required http.Server and gets it listening for
 // each addr passed in and does protocol specific checking.
 func ListenAndServe(proto, addr string, job *engine.Job) error {
+	var l net.Listener
 	r, err := createRouter(job.Eng, job.GetenvBool("Logging"), job.GetenvBool("EnableCors"), job.Getenv("Version"))
 	if err != nil {
 		return err
@@ -1208,7 +1209,11 @@ func ListenAndServe(proto, addr string, job *engine.Job) error {
 		}
 	}
 
-	l, err := listenbuffer.NewListenBuffer(proto, addr, activationLock)
+	if job.GetenvBool("BufferRequests") {
+		l, err = listenbuffer.NewListenBuffer(proto, addr, activationLock)
+	} else {
+		l, err = net.Listen(proto, addr)
+	}
 	if err != nil {
 		return err
 	}

components/engine/docker/docker.go

@@ -185,6 +185,7 @@ func main() {
 		job.Setenv("TlsCa", *flCa)
 		job.Setenv("TlsCert", *flCert)
 		job.Setenv("TlsKey", *flKey)
+		job.SetenvBool("BuffferRequests", true)
 		if err := job.Run(); err != nil {
 			log.Fatal(err)
 		}