VOL-381 add unum container to support ONOS cluster formation under swarm
Change-Id: Ic260edda19bb199ed040f05164ab605f28c919d0
diff --git a/unum/listener.go b/unum/listener.go
new file mode 100644
index 0000000..c63b347
--- /dev/null
+++ b/unum/listener.go
@@ -0,0 +1,77 @@
+// Copyright 2017 the original author or authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+ "net/http"
+
+ "bytes"
+
+ "github.com/gorilla/mux"
+ "sync"
+)
+
+var configMutex sync.Mutex
+
+type Listener struct {
+ ListenOn string
+ Update chan []byte
+
+ router *mux.Router
+ clusterConfig []byte
+}
+
+func (l *Listener) Init() {
+ l.router = mux.NewRouter()
+ l.router.HandleFunc("/config", l.ConfigHandler).Methods("GET")
+ l.router.HandleFunc("/config/", l.ConfigHandler).Methods("GET")
+ l.clusterConfig = []byte("{}")
+ l.Update = make(chan []byte)
+ go l.updateHandler()
+}
+
+func (l *Listener) updateHandler() {
+ for {
+ next := <-l.Update
+
+ if !bytes.Equal(next, l.clusterConfig) {
+ log.Info("Cluster configuration modified")
+ configMutex.Lock()
+ l.clusterConfig = next
+ configMutex.Unlock()
+ } else {
+ log.Debug("Cluster update received, w/o change")
+ }
+ }
+}
+
+func (l *Listener) ListenAndServe() error {
+ log.Infof("Starting to listen for cluster configuration requests on '%s'",
+ l.ListenOn)
+ return http.ListenAndServe(l.ListenOn, l.router)
+}
+
+func (l *Listener) ConfigHandler(w http.ResponseWriter, r *http.Request) {
+ configMutex.Lock()
+ local := l.clusterConfig
+ configMutex.Unlock()
+ if len(local) == 0 {
+ w.WriteHeader(http.StatusNoContent)
+ return
+ }
+ w.Header().Add("content-type", "application/json")
+ w.Write(local)
+ return
+}