关于 express-demo
虽然 PM2 已有负载均衡的功能,但是他只对多进程之间进行处理,如果是多个服务器之间,就无法办到了,这里我们选用nginx。
服务器准备
s0:CentOS,172.16.70.175,nginx 服务器
s1:CentOS,172.16.70.174,web 服务器
s2:CentOS,172.16.70.173,web 服务器
1、配置 s1,s2
由于之前已有说明,这不再细说。参考:http://my.oschina.net/songzhu/blog/610337
修改 s1 服务器的 config.js 内容为:
var config = {
server:"172.16.70.174"
};
module.exports = config;
重启 web
pm2 restart pm2-start.json
修改 s2 服务器的 config.js 内容为:
var config = {
server:"172.16.70.173"
};
module.exports = config;
重启 web
pm2 restart pm2-start.json
2、配置 s0
安装 nginx
$ rpm -ivh http://nginx.org/packages/centos/7/x86_64/RPMS/nginx-1.8.0-1.el7.ngx.x86_64.rpm
启动 nginx
$ service nginx start
验证
$ curl http://localhost/
配置负载均衡,编辑 /etc/nginx/nginx.conf,在 http 节点里面增加以下内容:
upstream web-server {
server 172.16.70.173:3000;
server 172.16.70.174:3000;
}
server {
listen 80;
server_name my.server.com;
location / {
proxy_pass http://web-server;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
}
完整的 /etc/nginx/nginx.conf 内容如下:
user nginx;
worker_processes 1;
error_log /var/log/nginx/error.log warn;
pid /var/run/nginx.pid;
events {
worker_connections 1024;
}
http {
include /etc/nginx/mime.types;
default_type application/octet-stream;
log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for"';
access_log /var/log/nginx/access.log main;
sendfile on;
#tcp_nopush on;
keepalive_timeout 65;
#gzip on;
include /etc/nginx/conf.d/*.conf;
upstream web-server {
server 172.16.70.173:3000;
server 172.16.70.174:3000;
}
server {
listen 80;
server_name my.server.com;
location / {
proxy_pass http://web-server;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
}
}
编辑完成之后,重启 nginx
$ service nginx restart
修改本地hosts文件,增加:172.16.70.175 my.server.com
在本地执行:
$ curl http://my.server.com/
<!DOCTYPE html><html><head><title>Express</title><link rel="stylesheet" href="/stylesheets/style.css"></head><body><h1>Express</h1><p>Welcome to Express on 172.16.70.173</p></body></html>
$ curl http://my.server.com/
<!DOCTYPE html><html><head><title>Express</title><link rel="stylesheet" href="/stylesheets/style.css"></head><body><h1>Express</h1><p>Welcome to Express on 172.16.70.174</p></body></html>
$ curl http://my.server.com/
<!DOCTYPE html><html><head><title>Express</title><link rel="stylesheet" href="/stylesheets/style.css"></head><body><h1>Express</h1><p>Welcome to Express on 172.16.70.173</p></body></html>
$ curl http://my.server.com/
<!DOCTYPE html><html><head><title>Express</title><link rel="stylesheet" href="/stylesheets/style.css"></head><body><h1>Express</h1><p>Welcome to Express on 172.16.70.174</p></body></html>
结果和预期一样,nginx 成功将请求平均分配到两台服务器上了。
3、遇到的问题
502 bag getway.
通过查看错误日志:
$ cat /var/log/nginx/error.log
发现具体的错误是:connect() to 172.16.70.174:3000 failed (13: Permission denied) while connecting to upstream, client: 172.16.70.9, server: my.server.com, request: "GET / HTTP/1.1", upstream: "http://172.16.70.174:3000/", host: "my.server.com:80"
解决办法是,执行以下命令
$ sudo setsebool -P httpd_can_network_connect 1
$ service nginx restart
解决错误参考网址:http://blog.frag-gustav.de/2013/07/21/nginx-selinux-me-mad/
项目代码:https://git.oschina.net/cavintang/express-demo.git
来源:oschina
链接:https://my.oschina.net/u/105194/blog/610376