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Version: 4.x

使用多个节点

部署多个 Socket.IO 服务器时,需要注意两件事:

  • 如果启用了 HTTP 长轮询(这是默认设置),则启用粘性会话:见下文
  • 使用兼容的适配器,请参见此处

粘性负载平衡

如果您计划在不同的进程或机器之间分配连接负载,则必须确保与特定会话 ID 关联的所有请求都到达发起它们的进程。

为什么需要粘性会话

这是因为 HTTP 长轮询传输在 Socket.IO 会话的生命周期内发送多个 HTTP 请求。

事实上,Socket.IO 在技术上可以在没有粘性会话的情况下工作,具有以下同步(虚线):

Using multiple nodes without sticky sessions

虽然显然可以实现,但我们认为 Socket.IO 服务器之间的这种同步过程会对您的应用程序造成很大的性能影响。

评论:

  • 如果不启用粘性会话,由于“会话 ID 未知”,您将遇到 HTTP 400 错误
  • WebSocket 传输没有这个限制,因为它依赖于整个会话的单个 TCP 连接。这意味着如果您禁用 HTTP 长轮询传输(这在 2021 年是一个完全有效的选择),您将不需要粘性会话:
const socket = io("https://io.yourhost.com", {
// WARNING: in that case, there is no fallback to long-polling
transports: [ "websocket" ] // or [ "websocket", "polling" ] (the order matters)
});

文档:transports

启用粘性会话

要实现粘性会话,主要有两种解决方案:

  • 基于 cookie 路由客户端(推荐解决方案)
  • 根据客户端的原始地址路由客户端

您将在下面找到一些常见负载平衡解决方案的示例:

其他平台请参考相关文档:

重要提示:如果您处于 CORS 情况(前端域与服务器域不同)并且会话亲和性是通过 cookie 实现的,则需要允许凭据:

服务器

const io = require("socket.io")(httpServer, {
cors: {
origin: "https://front-domain.com",
methods: ["GET", "POST"],
credentials: true
}
});

客户端

const io = require("socket.io-client");
const socket = io("https://server-domain.com", {
withCredentials: true
});

没有它,浏览器将不会发送 cookie,您将遇到 HTTP 400“会话 ID 未知”响应。更多信息在这里.

NginX 配置

在文件的http { }部分中nginx.conf,您可以声明一个upstream包含要平衡负载的 Socket.IO 进程列表的部分:

http {
server {
listen 3000;
server_name io.yourhost.com;

location / {
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $host;

proxy_pass http://nodes;

# enable WebSockets
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
}
}

upstream nodes {
# enable sticky session with either "hash" (uses the complete IP address)
hash $remote_addr consistent;
# or "ip_hash" (uses the first three octets of the client IPv4 address, or the entire IPv6 address)
# ip_hash;
# or "sticky" (needs commercial subscription)
# sticky cookie srv_id expires=1h domain=.example.com path=/;

server app01:3000;
server app02:3000;
server app03:3000;
}
}

请注意hash指示连接将是粘性的说明。

确保您还在worker_processes最顶层配置以指示 NginX 应该使用多少工作人员。您可能还想研究调整块worker_connections内的设置events { }

链接:

Apache HTTPD 配置

Header add Set-Cookie "SERVERID=sticky.%{BALANCER_WORKER_ROUTE}e; path=/" env=BALANCER_ROUTE_CHANGED

<Proxy "balancer://nodes_polling">
BalancerMember "http://app01:3000" route=app01
BalancerMember "http://app02:3000" route=app02
BalancerMember "http://app03:3000" route=app03
ProxySet stickysession=SERVERID
</Proxy>

<Proxy "balancer://nodes_ws">
BalancerMember "ws://app01:3000" route=app01
BalancerMember "ws://app02:3000" route=app02
BalancerMember "ws://app03:3000" route=app03
ProxySet stickysession=SERVERID
</Proxy>

RewriteEngine On
RewriteCond %{HTTP:Upgrade} =websocket [NC]
RewriteRule /(.*) balancer://nodes_ws/$1 [P,L]
RewriteCond %{HTTP:Upgrade} !=websocket [NC]
RewriteRule /(.*) balancer://nodes_polling/$1 [P,L]

ProxyTimeout 3

链接:

HAProxy 配置

# Reference: http://blog.haproxy.com/2012/11/07/websockets-load-balancing-with-haproxy/

listen chat
bind *:80
default_backend nodes

backend nodes
option httpchk HEAD /health
http-check expect status 200
cookie io prefix indirect nocache # using the `io` cookie set upon handshake
server app01 app01:3000 check cookie app01
server app02 app02:3000 check cookie app02
server app03 app03:3000 check cookie app03

链接:

Traefik

使用容器标签:

# docker-compose.yml
services:
traefik:
image: traefik:2.4
volumes:
- /var/run/docker.sock:/var/run/docker.sock
links:
- server

server:
image: my-image:latest
labels:
- "traefik.http.routers.my-service.rule=PathPrefix(`/`)"
- traefik.http.services.my-service.loadBalancer.sticky.cookie.name=server_id
- traefik.http.services.my-service.loadBalancer.sticky.cookie.httpOnly=true

使用文件提供程序

## Dynamic configuration
http:
services:
my-service:
rule: "PathPrefix(`/`)"
loadBalancer:
sticky:
cookie:
name: server_id
httpOnly: true

链接:

使用 Node.js 集群

就像 NginX 一样,Node.js 通过cluster模块提供了内置的集群支持。

有几种解决方案,具体取决于您的用例:

NPM 包这个怎么运作
@socket.io/sticky路由基于sid查询参数
sticky-session路由是基于connection.remoteAddress
socketio-sticky-session基于x-forwarded-for报头的路由)

示例@socket.io/sticky:

const cluster = require("cluster");
const http = require("http");
const { Server } = require("socket.io");
const numCPUs = require("os").cpus().length;
const { setupMaster, setupWorker } = require("@socket.io/sticky");
const { createAdapter, setupPrimary } = require("@socket.io/cluster-adapter");

if (cluster.isMaster) {
console.log(`Master ${process.pid} is running`);

const httpServer = http.createServer();

// setup sticky sessions
setupMaster(httpServer, {
loadBalancingMethod: "least-connection",
});

// setup connections between the workers
setupPrimary();

// needed for packets containing buffers (you can ignore it if you only send plaintext objects)
// Node.js < 16.0.0
cluster.setupMaster({
serialization: "advanced",
});
// Node.js > 16.0.0
// cluster.setupPrimary({
// serialization: "advanced",
// });

httpServer.listen(3000);

for (let i = 0; i < numCPUs; i++) {
cluster.fork();
}

cluster.on("exit", (worker) => {
console.log(`Worker ${worker.process.pid} died`);
cluster.fork();
});
} else {
console.log(`Worker ${process.pid} started`);

const httpServer = http.createServer();
const io = new Server(httpServer);

// use the cluster adapter
io.adapter(createAdapter());

// setup connection with the primary process
setupWorker(io);

io.on("connection", (socket) => {
/* ... */
});
}

在节点之间传递事件

既然您有多个接受连接的Socket.IO 节点,如果您想向所有客户端(或某个房间中的客户端)广播事件,您将需要某种方式在进程或计算机之间传递消息。

负责路由消息的接口就是我们所说的Adapter