Go clone of https://gist.github.com/sh7dm/ed4461a3eb3ae857e97da7488919a645

chatServer.go

package main

import (
	"fmt"
	"math/rand"
	"strconv"

	"github.com/go-redis/redis"

	"github.com/kataras/iris"
	"github.com/kataras/iris/websocket"

	"github.com/kataras/iris/middleware/logger"
	"github.com/kataras/iris/middleware/recover"
)

func main() {
	port := strconv.Itoa(rand.Intn(8000) + 1000) // Random port

	redisdb := redis.NewClient(&redis.Options{
		Addr:     "172.17.0.2:6379", // Redis address
		Password: "", // no password set
		DB:       0,  // use default DB
	})

	sub := redisdb.Subscribe("mychannel1")
	subCh := sub.Channel()
	defer sub.Close()

	app := iris.New()
	app.Logger().SetLevel("debug")
	app.Use(recover.New())
	app.Use(logger.New())

	app.Get("/", func(ctx iris.Context) {
    // Code from https://codepen.io/matt-west/pen/tHlBb
		ctx.HTML(`
		<div id="page-wrapper">
			<h1>WebSockets Demo</h1>
			
			<div id="status">Connecting...</div>
			
			<ul id="messages"></ul>
			
			<form id="message-form" action="#" method="post">
				<textarea id="message" placeholder="Write your message here..." required></textarea>
				<button type="submit">Send Message</button>
				<button type="button" id="close">Close Connection</button>
			</form>
		</div>
		<style>
		*, *:before, *:after {
			-moz-box-sizing: border-box;
			-webkit-box-sizing: border-box;
			box-sizing: border-box;
		  }
		  
		  html {
			font-family: Helvetica, Arial, sans-serif;
			font-size: 100%;
			background: #333;
		  }
		  
		  #page-wrapper {
			width: 650px;
			background: #FFF;
			padding: 1em;
			margin: 1em auto;
			border-top: 5px solid #69c773;
			box-shadow: 0 2px 10px rgba(0,0,0,0.8);
		  }
		  
		  h1 {
			  margin-top: 0;
		  }
		  
		  #status {
			font-size: 0.9rem;
			margin-bottom: 1rem;
		  }
		  
		  .open {
			color: green;
		  }
		  
		  .closed {
			color: red;
		  }
		  
		  
		  ul {
			list-style: none;
			margin: 0;
			padding: 0;
			font-size: 0.95rem;
		  }
		  
		  ul li {
			padding: 0.5rem 0.75rem;
			border-bottom: 1px solid #EEE;
		  }
		  
		  ul li:first-child {
			border-top: 1px solid #EEE;
		  }
		  
		  ul li span {
			display: inline-block;
			width: 90px;
			font-weight: bold;
			color: #999;
			font-size: 0.7rem;
			text-transform: uppercase;
			letter-spacing: 1px;
		  }
		  
		  .sent {
			background-color: #F7F7F7;
		  }
		  
		  .received {}
		  
		  #message-form {
			margin-top: 1.5rem;
		  }
		  
		  textarea {
			width: 100%;
			padding: 0.5rem;
			font-size: 1rem;
			border: 1px solid #D9D9D9;
			border-radius: 3px;
			box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.1);
			min-height: 100px;
			margin-bottom: 1rem;
		  }
		  
		  button {
			display: inline-block;
			border-radius: 3px;
			border: none;
			font-size: 0.9rem;
			padding: 0.6rem 1em;
			color: white;
			margin: 0 0.25rem;
			text-align: center;
			background: #BABABA;
			border-bottom: 1px solid #999;
		  }
		  
		  button[type="submit"] {
			background: #86b32d;
			border-bottom: 1px solid #5d7d1f;
		  }
		  
		  button:hover {
			opacity: 0.75;
			cursor: pointer;
		  }		  
		</style>
		<script>
      window.onload = function() {

			// Get references to elements on the page.
			var form = document.getElementById('message-form');
			var messageField = document.getElementById('message');
			var messagesList = document.getElementById('messages');
			var socketStatus = document.getElementById('status');
			var closeBtn = document.getElementById('close');
		  
		  
			// Create a new WebSocket.
			var socket = new WebSocket('ws://localhost:` + port + `/ws');
		  
		  
			// Handle any errors that occur.
			socket.onerror = function(error) {
			  console.log('WebSocket Error: ' + error);
			};
		  
			// Show a connected message when the WebSocket is opened.
			socket.onopen = function(event) {
			  socketStatus.innerHTML = 'Connected to: ' + event.currentTarget.url;
			  socketStatus.className = 'open';
			};
		  
		  
			// Handle messages sent by the server.
			socket.onmessage = function(event) {
			  var message = event.data;
			  messagesList.innerHTML += '<li class="received"><span>Received:</span>' + message + '</li>';
			};
		  
		  
			// Show a disconnected message when the WebSocket is closed.
			socket.onclose = function(event) {
			  socketStatus.innerHTML = 'Disconnected from WebSocket.';
			  socketStatus.className = 'closed';
			};
		  
		  
			// Send a message when the form is submitted.
			form.onsubmit = function(e) {
			  e.preventDefault();
		  
			  // Retrieve the message from the textarea.
			  var message = messageField.value;
		  
			  // Send the message through the WebSocket.
			  socket.send(message);
		  
			  // Add the message to the messages list.
			  messagesList.innerHTML += '<li class="sent"><span>Sent:</span>' + message + '</li>';
		  
			  // Clear out the message field.
			  messageField.value = '';
		  
			  return false;
			};
		  
		  
			// Close the WebSocket connection when the close button is clicked.
			closeBtn.onclick = function(e) {
			  e.preventDefault();
		  
			  // Close the WebSocket.
			  socket.close();
		  
			  return false;
			};
		  
		  };
		</script>
		`)
	})

	ws := websocket.New(websocket.Config{
		ReadBufferSize:  1024,
		WriteBufferSize: 1024,
	})
	ws.OnConnection(func(c websocket.Connection) {
		// Read events from browser
		c.OnMessage(func(msg []byte) {
			// Print the message to the console, c.Context() is the iris's http context.
			fmt.Printf("%s sent: %s\n", c.Context().RemoteAddr(), msg)

			err := redisdb.Publish("mychannel1", msg).Err()
			if err != nil {
				panic(err)
			}
		})

		go (func() {
			for msg := range subCh {
				// Write message back to the client message owner with:
				// c.Emit("chat", msg)
				// Write message to all except this client with:
				c.To(websocket.Broadcast).EmitMessage([]byte(msg.Payload))
				// + echo
				c.EmitMessage([]byte(msg.Payload))
			}
		})()
	})

	app.Get("/ws", ws.Handler())

	app.Run(iris.Addr(":"+port), iris.WithoutServerError(iris.ErrServerClosed))
}