From f36d55f062eb30e06db104852d00f9e19e49f000 Mon Sep 17 00:00:00 2001
From: Xiang Li <xiang.li@coreos.com>
Date: Wed, 21 Jan 2015 22:59:58 -0800
Subject: [PATCH] next-version-handler

---
 server/peer_server.go          |  1 +
 server/peer_server_handlers.go | 43 ++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/server/peer_server.go b/server/peer_server.go
index eda20fc3d..9b2190544 100644
--- a/server/peer_server.go
+++ b/server/peer_server.go
@@ -370,6 +370,7 @@ func (s *PeerServer) HTTPHandler() http.Handler {
 	router.HandleFunc("/v2/admin/machines", s.getMachinesHttpHandler).Methods("GET")
 	router.HandleFunc("/v2/admin/machines/{name}", s.getMachineHttpHandler).Methods("GET")
 	router.HandleFunc("/v2/admin/machines/{name}", s.RemoveHttpHandler).Methods("DELETE")
+	router.HandleFunc("/v2/admin/next-internal-version", s.NextInternalVersionHandler).Methods("GET")
 
 	return router
 }
diff --git a/server/peer_server_handlers.go b/server/peer_server_handlers.go
index 2696956de..2d561d279 100644
--- a/server/peer_server_handlers.go
+++ b/server/peer_server_handlers.go
@@ -3,6 +3,7 @@ package server
 import (
 	"encoding/json"
 	"net/http"
+	"path"
 	"strconv"
 	"time"
 
@@ -309,6 +310,48 @@ func (ps *PeerServer) UpgradeHttpHandler(w http.ResponseWriter, req *http.Reques
 	w.WriteHeader(http.StatusOK)
 }
 
+func (ps *PeerServer) NextInternalVersionHandler(w http.ResponseWriter, req *http.Request) {
+	for i := 0; i < 50; i++ {
+		if ps.raftServer.State() != raft.Leader {
+			l := ps.raftServer.Leader()
+			if l == "" {
+				time.Sleep(5 * time.Second)
+				continue
+			}
+			url, _ := ps.registry.PeerURL(l)
+			uhttp.Redirect(url, w, req)
+			return
+		}
+		resp, err := ps.store.Get("/_etcd/available-internal-versions/2", true, true)
+		if err != nil {
+			time.Sleep(5 * time.Second)
+			continue
+		}
+		available := make(map[string]bool)
+		for _, n := range resp.Node.Nodes {
+			available[path.Base(n.Key)] = true
+		}
+
+		notfound := false
+		for _, n := range ps.registry.Names() {
+			if !available[n] {
+				notfound = true
+				break
+			}
+		}
+		if notfound {
+			time.Sleep(5 * time.Second)
+			continue
+		}
+		c := ps.store.CommandFactory().CreateSetCommand("/_etcd/next-internal-version", false, "2", store.Permanent)
+		_, err = ps.raftServer.Do(c)
+		if err == nil {
+			return
+		}
+	}
+	w.WriteHeader(http.StatusServiceUnavailable)
+}
+
 // machineMessage represents information about a peer or standby in the registry.
 type machineMessage struct {
 	Name      string `json:"name"`