Implement websockets and add support for list monitor url's

Gopkg.toml

@@ -72,3 +72,7 @@
 [[constraint]]
   name = "github.com/aws/aws-sdk-go"
   version = "1.16.15"
+
+[[constraint]]
+  name = "github.com/gorilla/websocket"
+  version = "1.4.0"

client.go

@@ -0,0 +1,76 @@
+package main
+
+import (
+	"flag"
+	"log"
+	"net/url"
+	"os"
+	"os/signal"
+	"time"
+
+	"github.com/gorilla/websocket"
+)
+
+var addr = flag.String("addr", "localhost:8080", "http service address")
+
+func main() {
+	flag.Parse()
+	log.SetFlags(0)
+
+	interrupt := make(chan os.Signal, 1)
+	signal.Notify(interrupt, os.Interrupt)
+
+	u := url.URL{Scheme: "ws", Host: *addr, Path: "/api/echo"}
+	log.Printf("connecting to %s", u.String())
+
+	c, _, err := websocket.DefaultDialer.Dial(u.String(), nil)
+	if err != nil {
+		log.Fatal("dial:", err)
+	}
+	defer c.Close()
+
+	done := make(chan struct{})
+
+	go func() {
+		defer close(done)
+		for {
+			_, message, err := c.ReadMessage()
+			if err != nil {
+				log.Println("read:", err)
+				return
+			}
+			log.Printf("recv: %s", message)
+		}
+	}()
+
+	ticker := time.NewTicker(time.Second)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-done:
+			return
+		case t := <-ticker.C:
+			err := c.WriteMessage(websocket.TextMessage, []byte(t.String()))
+			if err != nil {
+				log.Println("write:", err)
+				return
+			}
+		case <-interrupt:
+			log.Println("interrupt")
+
+			// Cleanly close the connection by sending a close message and then
+			// waiting (with timeout) for the server to close the connection.
+			err := c.WriteMessage(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseNormalClosure, ""))
+			if err != nil {
+				log.Println("write close:", err)
+				return
+			}
+			select {
+			case <-done:
+			case <-time.After(time.Second):
+			}
+			return
+		}
+	}
+}

internal/api/api.go

@@ -59,6 +59,10 @@ func integrationRoutes(router *mux.Router) {
 	router.HandleFunc("/integrations/{integrationID}", DeleteIntegrationHandler).Methods("DELETE")
 }
 
+func websocketRoutes(router *mux.Router) {
+	router.HandleFunc("/echo", EchoHandler)
+}
+
 // StartServer Start the server.
 func StartServer() {
 	router := mux.NewRouter().PathPrefix("/api").Subrouter()
@@ -70,6 +74,7 @@ func StartServer() {
 	authRoutes(router)
 	userRoutes(router)
 	dashboardRoutes(router)
+	websocketRoutes(router)
 
 	http.ListenAndServe(":8080", handlers.CORS(
 		handlers.AllowedHeaders([]string{"Content-Type", "Authorization"}),

internal/api/websockets.go

@@ -0,0 +1,33 @@
+package api
+
+import (
+	"log"
+	"net/http"
+
+	"github.com/gorilla/websocket"
+)
+
+var upgrader = websocket.Upgrader{} // use default options
+
+// EchoHandler sample websocket endpoint
+func EchoHandler(w http.ResponseWriter, r *http.Request) {
+	c, err := upgrader.Upgrade(w, r, nil)
+	if err != nil {
+		log.Print("upgrade:", err)
+	}
+
+	defer c.Close()
+	for {
+		mt, message, err := c.ReadMessage()
+		if err != nil {
+			log.Println("read:", err)
+			break
+		}
+		log.Printf("recv: %s", message)
+		err = c.WriteMessage(mt, message)
+		if err != nil {
+			log.Println("write:", err)
+			break
+		}
+	}
+}