Add proxy mode.

server/server.go

@@ -164,6 +164,17 @@ func (s *Server) handleFunc(r *mux.Router, path string, f func(http.ResponseWrit
 		// Log request.
 		log.Debugf("[recv] %s %s %s [%s]", req.Method, s.URL(), req.URL.Path, req.RemoteAddr)
 
+		// Forward request along if the server is a proxy.
+		if s.peerServer.Mode() == ProxyMode {
+			if s.peerServer.proxyClientURL == "" {
+				w.Header().Set("Content-Type", "application/json")
+				etcdErr.NewError(402, "", 0).Write(w)
+				return
+			}
+			uhttp.Redirect(s.peerServer.proxyClientURL, w, req)
+			return
+		}
+
 		// Execute handler function and return error if necessary.
 		if err := f(w, req); err != nil {
 			if etcdErr, ok := err.(*etcdErr.Error); ok {
@@ -206,6 +217,9 @@ func (s *Server) Dispatch(c raft.Command, w http.ResponseWriter, req *http.Reque
 			return etcdErr.NewError(300, "Empty result from raft", s.Store().Index())
 		}
 
+		w.Header().Set("X-Leader-Client-URL", s.url)
+		w.Header().Set("X-Leader-Peer-URL", ps.Config.URL)
+
 		// response for raft related commands[join/remove]
 		if b, ok := result.([]byte); ok {
 			w.WriteHeader(http.StatusOK)
@@ -239,25 +253,24 @@ func (s *Server) Dispatch(c raft.Command, w http.ResponseWriter, req *http.Reque
 
 		return nil
 
-	} else {
-		leader := ps.raftServer.Leader()
-
-		// No leader available.
-		if leader == "" {
-			return etcdErr.NewError(300, "", s.Store().Index())
-		}
-
-		var url string
-		switch c.(type) {
-		case *JoinCommand, *RemoveCommand:
-			url, _ = ps.registry.PeerURL(leader)
-		default:
-			url, _ = ps.registry.ClientURL(leader)
-		}
-		uhttp.Redirect(url, w, req)
-
-		return nil
 	}
+
+	leader := ps.raftServer.Leader()
+	if leader == "" {
+		return etcdErr.NewError(300, "", s.Store().Index())
+	}
+
+	var url string
+	switch c.(type) {
+	case *JoinCommand, *RemoveCommand:
+		url, _ = ps.registry.PeerURL(leader)
+	default:
+		url, _ = ps.registry.ClientURL(leader)
+	}
+
+	uhttp.Redirect(url, w, req)
+
+	return nil
 }
 
 // Handler to return the current version of etcd.