负载均衡可以把用户的请求分摊到多个服务器上进行处理,从而实现了对海量用户的访问支持。负载均衡的架构如图所示:
对于复杂的Web应用来说,用Nginx做前端负载均衡是理所当然的事。
下面,我们用Nginx做NodeJS应用的负载均衡。
1、配置Nginx 修改nginx.conf:upstream sample {
server 127.0.0.1:3000;
server 127.0.0.1:3001;
keepalive 64;
}
server {
listen 80;
….
server_name 127.0.0.1;
….
location / {
proxy_redirect off;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header Host $http_host;
proxy_set_header X-NginX-Proxy true;
proxy_set_header Connection “”;
proxy_http_version 1.1;
proxy_pass http://sample;
}
}
这里在3000端口和3001端口各有一个Node.js服务器,这两个服务器在做同样的工作。在upstream节,配置了两个Node.js服务器。此外,我们还设置了proxy_pass http://sample做HTTP请求代理。
2、构建NodeJS服务器
var http = require(http);
var morgan = require(morgan);
var server1 = http.createServer(function (req, res) {
console.log(“Request for: “ + req.url + “– port 3000 “);
res.writeHead(200, {Content-Type: text/plain});
res.end(Hello Node.js\n);
}).listen(3000, “127.0.0.1”);
var server2 = http.createServer(function (req, res) {
console.log(“Request for: “ + req.url + “– port 3001 “);
res.writeHead(200, {Content-Type: text/plain});
res.end(Hello Node.js\n);
}).listen(3001, “127.0.0.1”);
server1.once(listening, function() {
console.log(Server running at http://127.0.0.1:3000/);
});
server2.once(listening, function() {
console.log(Server running at http://127.0.0.1:3001/);
});
3、访问Nginx服务器
现在我们可以访问http://127.0.0.1
可以看到如下的输出:Server running at http://127.0.0.1:3000/
Server running at http://127.0.0.1:3001/
Request for: /– port 3001
Request for: /favicon.ico– port 3000
Request for: /favicon.ico– port 3001
Request for: /– port 3000
Request for: /favicon.ico– port 3001
Request for: /favicon.ico– port 3000
Request for: /– port 3001
Request for: /favicon.ico– port 3000
Request for: /favicon.ico– port 3001
Request for: /– port 3000
Request for: /favicon.ico– port 3001
Request for: /favicon.ico– port 3000