Plugins JSON spec.

Allow full configuration of external plugins via a JSON document.

Signed-off-by: David Calavera <david.calavera@gmail.com>

sockets/tcp_socket.go

@@ -3,6 +3,8 @@ package sockets
 import (
 	"crypto/tls"
 	"net"
+	"net/http"
+	"time"
 
 	"github.com/docker/docker/pkg/listenbuffer"
 )
@@ -18,3 +20,18 @@ func NewTcpSocket(addr string, tlsConfig *tls.Config, activate <-chan struct{})
 	}
 	return l, nil
 }
+
+func ConfigureTCPTransport(tr *http.Transport, proto, addr string) {
+	// Why 32? See https://github.com/docker/docker/pull/8035.
+	timeout := 32 * time.Second
+	if proto == "unix" {
+		// No need for compression in local communications.
+		tr.DisableCompression = true
+		tr.Dial = func(_, _ string) (net.Conn, error) {
+			return net.DialTimeout(proto, addr, timeout)
+		}
+	} else {
+		tr.Proxy = http.ProxyFromEnvironment
+		tr.Dial = (&net.Dialer{Timeout: timeout}).Dial
+	}
+}