dockerfile, handler, main, index: fix closing the connection when sending a message from the local host

Author: GopherSuslik

Dockerfile

@@ -11,6 +11,7 @@ FROM alpine:latest
 WORKDIR /opt/
 
 COPY --from=builder /github.com/Lapp-coder/websocket-chat/build/bin/chat .
+COPY --from=builder /github.com/Lapp-coder/websocket-chat/index.html .
 
 EXPOSE 8080
 

handler.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"github.com/gorilla/websocket"
+	"html/template"
 	"net/http"
 )
 
@@ -10,6 +11,8 @@ var upgrader = websocket.Upgrader{
 	WriteBufferSize: 1024,
 }
 
+var indexTemplate *template.Template
+
 type handler struct {
 	hub *hub
 }
@@ -24,7 +27,7 @@ func (h *handler) initRoutes() {
 }
 
 func (h *handler) index(w http.ResponseWriter, r *http.Request) {
-	http.ServeFile(w, r, "index.html")
+	indexTemplate.Execute(w, r.Host)
 }
 
 func (h *handler) chat(w http.ResponseWriter, r *http.Request) {

index.html

@@ -28,7 +28,7 @@
                 });
 
                 if (window["WebSocket"]) {
-                    conn = new WebSocket("ws://localhost:8080/chat");
+                    conn = new WebSocket("ws://{{$}}/chat");
                     conn.onclose = function(evt) {
                         appendLog($("<div><b>Соединение закрыто.</b></div>"))
                     }

main.go

@@ -3,12 +3,14 @@ package main
 import (
 	"context"
 	"github.com/sirupsen/logrus"
+	"html/template"
 	"os"
 	"os/signal"
 	"syscall"
 )
 
 func main() {
+	indexTemplate = template.Must(template.ParseFiles("index.html"))
 	hub := newHub()
 	handler := newHandler(hub)
 	handler.initRoutes()