Add websocket example

controllers/gce/examples/websocket/server.go

@@ -0,0 +1,81 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+	"time"
+
+	"github.com/gorilla/websocket"
+)
+
+var podName string
+var upgrader = websocket.Upgrader{
+	CheckOrigin: func(r *http.Request) bool {
+		return true // Ignore http origin
+	},
+}
+
+func init() {
+	podName = os.Getenv("podname")
+}
+
+func ws(w http.ResponseWriter, r *http.Request) {
+	log.Println("Received request", r.RemoteAddr)
+	c, err := upgrader.Upgrade(w, r, nil)
+	if err != nil {
+		log.Println("failed to upgrade:", err)
+		return
+	}
+	defer c.Close()
+
+	s := fmt.Sprintf("Connected to %v", podName)
+	c.WriteMessage(websocket.TextMessage, []byte(s))
+	handleWSConn(c)
+}
+
+func handleWSConn(c *websocket.Conn) {
+	stop := make(chan struct{})
+	go func() {
+		for {
+			time.Sleep(5 * time.Second)
+
+			select {
+			case <-stop:
+				return
+			default:
+			}
+
+			s := fmt.Sprintf("%s reports time: %v", podName, time.Now().String())
+			c.WriteMessage(websocket.TextMessage, []byte(s))
+		}
+	}()
+	for {
+		mt, message, err := c.ReadMessage()
+		if err != nil {
+			log.Println("Error while reading:", err)
+			break
+		}
+		if err = c.WriteMessage(mt, message); err != nil {
+			log.Println("Error while writing:", err)
+			break
+		}
+	}
+	close(stop)
+}
+
+func root(w http.ResponseWriter, r *http.Request) {
+	if r.URL.Path != "/" {
+		http.NotFound(w, r)
+		return
+	}
+	w.Write([]byte(`Websocket example. Connect to /ws`))
+}
+
+func main() {
+	log.Println("Starting")
+	http.HandleFunc("/ws", ws)
+	http.HandleFunc("/", root)
+	log.Fatal(http.ListenAndServe(":8080", nil))
+}