openresty+websocket+redis simple chat

openresty 很早就支持websocket了,但是早期的版本cosocket是单工的,处理起来比较麻烦参见邮件列表讨论 websocket chat,后来的版本cosocket是双全工的,就可以按照这个讨论的方案来实现基于websocket的聊天,或者是push程序了,但是网络上没有找到一个具体一点的例子,于是自己写了个simple的例子。

1 思路

client的websocket连接到openresty之后,使用ngx.thread.spawn启动两个 轻线程,一个用来接收客户端提交的数据往redis的channel写,另一个用来订阅channel,读取redis的数据写给客户端。channel相当于一个chat room,多个client一起订阅,有人发聊天信息(pub),所有人都能得到信息(sub)。代码比较简陋,简单的思路的实现。

2 服务端代码

依赖:

  • openresty
  • redis
  • lua-resty-redis
  • lua-resty-websocket 只支持RFC 6455

nginx的配置全贴了,就是两个location,一个是页面地址,一个是websocket地址。

配置片段

    location = /sredis { content_by_lua_file conf/lua/ws_redis.lua; }

    location ~ /ws/(.*) { alias conf/html/$1.html; }

lua代码

-- simple chat with redis
local server = require "resty.websocket.server"
local redis = require "resty.redis"

local channel_name = "chat"
local msg_id = 0

--create connection
local wb, err = server:new{
  timeout = 10000,
  max_payload_len = 65535
}

--create success
if not wb then
  ngx.log(ngx.ERR, "failed to new websocket: ", err)
  return ngx.exit(444)
end


local push = function()
    -- --create redis
    local red = redis:new()
    red:set_timeout(5000) -- 1 sec
    local ok, err = red:connect("127.0.0.1", 6379)
    if not ok then
        ngx.log(ngx.ERR, "failed to connect redis: ", err)
        wb:send_close()
        return
    end

    --sub
    local res, err = red:subscribe(channel_name)
    if not res then
        ngx.log(ngx.ERR, "failed to sub redis: ", err)
        wb:send_close()
        return
    end

    -- loop : read from redis
    while true do
        local res, err = red:read_reply()
        if res then
            local item = res[3]
            local bytes, err = wb:send_text(tostring(msg_id).." "..item)
            if not bytes then
                -- better error handling
                ngx.log(ngx.ERR, "failed to send text: ", err)
                return ngx.exit(444)
            end
            msg_id = msg_id + 1
        end
    end
end


local co = ngx.thread.spawn(push)

--main loop
while true do
    -- 获取数据
    local data, typ, err = wb:recv_frame()

    -- 如果连接损坏 退出
    if wb.fatal then
        ngx.log(ngx.ERR, "failed to receive frame: ", err)
        return ngx.exit(444)
    end

    if not data then
        local bytes, err = wb:send_ping()
        if not bytes then
          ngx.log(ngx.ERR, "failed to send ping: ", err)
          return ngx.exit(444)
        end
        ngx.log(ngx.ERR, "send ping: ", data)
    elseif typ == "close" then
        break
    elseif typ == "ping" then
        local bytes, err = wb:send_pong()
        if not bytes then
            ngx.log(ngx.ERR, "failed to send pong: ", err)
            return ngx.exit(444)
        end
    elseif typ == "pong" then
        ngx.log(ngx.ERR, "client ponged")
    elseif typ == "text" then
        --send to redis
        local red2 = redis:new()
        red2:set_timeout(1000) -- 1 sec
        local ok, err = red2:connect("127.0.0.1", 6379)
        if not ok then
            ngx.log(ngx.ERR, "failed to connect redis: ", err)
            break
        end
        local res, err = red2:publish(channel_name, data)
        if not res then
            ngx.log(ngx.ERR, "failed to publish redis: ", err)
        end
    end
end

wb:send_close()
ngx.thread.wait(co)

3 页面代码

<!DOCTYPE HTML>
<html>

<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no">
    <script type="text/javascript"> var ws = null; function WebSocketConn() { if (ws != null && ws.readyState == 1) { log("已经在线"); return } if ("WebSocket" in window) { // Let us open a web socket ws = new WebSocket("ws://localhost:8008/sredis"); ws.onopen = function() { log('成功进入聊天室'); }; ws.onmessage = function(event) { log(event.data) }; ws.onclose = function() { // websocket is closed. log("已经和服务器断开"); }; ws.onerror = function(event) { console.log("error " + event.data); }; } else { // The browser doesn't support WebSocket alert("WebSocket NOT supported by your Browser!"); } } function SendMsg() { if (ws != null && ws.readyState == 1) { var msg = document.getElementById('msgtext').value; ws.send(msg); } else { log('请先进入聊天室'); } } function WebSocketClose() { if (ws != null && ws.readyState == 1) { ws.close(); log("发送断开服务器请求"); } else { log("当前没有连接服务器") } } function log(text) { var li = document.createElement('li'); li.appendChild(document.createTextNode(text)); document.getElementById('log').appendChild(li); return false; } </script>
</head>

<body>
    <div id="sse">
        <a href="javascript:WebSocketConn()">进入聊天室</a> &nbsp;
        <a href="javascript:WebSocketClose()">离开聊天室</a>
        <br>
        <br>
        <input id="msgtext" type="text">
        <br>
        <a href="javascript:SendMsg()">发送信息</a>
        <br>
        <ol id="log"></ol>
    </div>
</body>

</html>

4 效果

用iphone试了试,不好使,可能是websocket版本实现的问题。pc端测试可以正常使用。

Reading

  • 邮件列表讨论 websocket chat
  • Aapo Websocket with openresty

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