nginx+keepalived 负载均衡架构-白红宇

nginx+keepalived 负载均衡架构

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发布时间：2019-06-19

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上一篇博文通过Haproxy 实现了对后端web服务器的负载均衡，这次用nginx来完成这个任务，原理上大致一样，只是nginx只能对http和mail做负载均衡，这比较有局限性，但是它对正则表达式的支持好！下面直接看实验：

【实验环境】

nginx keepalived 主：192.168.56.120

nginx keepalived 从：192.168.56.121

VIP ：192.168.56.130

Web1 : 192.168.56.113

Web2：192.168.56.114

【实验拓扑】

一、安装配置nginx

1、配置主机名（node2同node1）

[root@localhost ~]# vim /etc/sysconfig/network

HOSTNAME=node1

[root@localhost ~]# vim /etc/hosts

192.168.56.120 node1

192.168.56.121 node2

192.168.56.113 web1

192.168.56.114 web2

[root@localhost ~]# hostname node1

2、安装配置nginx(node2配置同node1）

[root@node1 src]# useradd -s /sbin/nologin -M www

[root@node1 src]# wget

[root@node1 src]# yum -y install pcre-devel openssl-devel perl-ExtUtils-Embed

[root@node1 src]# tar xf nginx-1.5.3.tar.gz

[root@node1 src]# cd nginx-1.5.3

[root@node1 nginx-1.5.3]# ./configure --prefix=/usr/local/nginx --user=www --group=www --with-http_ssl_module --with-http_gzip_static_module --without-http_uwsgi_module --without-http_scgi_module --without-http_upstream_ip_hash_module --with-http_perl_module --with-pcre

[root@node1 nginx-1.5.3]# make && make install

配置nginx

[root@node1 ~]# vim /usr/local/nginx/conf/nginx.conf

user www www;

worker_processes 8;

error_log logs/error.log;

pid logs/nginx.pid;

events {

worker_connections 1024;

}

http {

include mime.types;

default_type application/octet-stream;

sendfile on;

tcp_nopush on;

keepalive_timeout 65;

gzip on;

upstream web_server_pool {

#ip_hash; #如果需要保持session一致，需要开启这个选项，可以保证同一台机器每次访问都分配到同一服务器

server 192.168.56.113:80 weight=4 max_fails=2 fail_timeout=30s;

server 192.168.56.114:80 weight=4 max_fails=2 fail_timeout=30s;

}

server {

listen 80;

server_name 192.168.56.120; # node2 改为192.168.56.121

location / {

root html;

index index.html index.htm;

proxy_pass http://web_server_pool;

proxy_set_header Host $host;

proxy_set_header X-Real-IP $remote_addr;

proxy_set_header X-Forwarded-For $remote_addr;

}

error_page 500 502 503 504 /50x.html;

location = /50x.html {

root html;

}

[root@node1 ~]# /usr/local/nginx/sbin/nginx -t

nginx: the configuration file /usr/local/nginx/conf/nginx.conf syntax is ok

nginx: configuration file /usr/local/nginx/conf/nginx.conf test is successfully

启动服务

[root@node1 ~]# /usr/local/nginx/sbin/nginx

3、安装配置web服务器

web服务器的配置（web2同web1，只需要将相应部分改为web2即可）

[root@localhost ~]# hostname web1

[root@web1 ~]# vim /etc/hosts

192.168.56.120 node1

192.168.56.121 node2

192.168.56.113 web1

192.168.56.114 web2

[root@web1 ~]# yum install -y httpd

[root@web1 ~]# service httpd start

[root@web1 ~]# echo "<h1>welcome to web1</h1>" > /var/www/html/index.html

4、测试Nginx负载均衡

在确保node1 的防火墙和selinux关闭的情况下，打开浏览器，访问

也可通过curl测试：

[root@node1 ~]# yum -y install curl

[root@node1 ~]# curl -dump http://192.168.56.120/

<h1>welcome to web1</h1>

[root@node1 ~]# curl -dump http://192.168.56.120/

<h1>welcome to web2</h1>

[root@node1 ~]# curl -dump http://192.168.56.120/

<h1>welcome to web1</h1>

[root@node1 ~]# curl -dump http://192.168.56.120/

<h1>welcome to web2</h1>

二、安装配置keepalived(node2配置参考node1，大体上一样)

1、安装配置keepalived

[root@node1 src]#

yum -y install popt popt-devel popt-static openssl-devel kernel-devel libnl libnl-devel

[root@node1 src]# wget http://www.keepalived.org/software/keepalived-1.2.4.tar.gz

[root@node1 src]# tar xf keepalived-1.2.4.tar.gz

[root@node1 src]# cd keepalived-1.2.4

[root@node1 keepalived-1.2.4]# ./configure --prefix=/usr/local/keepalived

[root@node1 keepalived-1.2.4]# make && make install

[root@node1 keepalived-1.2.4]# cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/

[root@node1 keepalived-1.2.4]# cp /usr/local/keepalived/sbin/keepalived /usr/sbin/

[root@node1 keepalived-1.2.4]# cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/

[root@node1 keepalived-1.2.4]# mkdir -p /etc/keepalived

[root@node1 keepalived-1.2.4]# cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/

[root@node1 keepalived-1.2.4]# chmod +x /etc/init.d/keepalived

配置

[root@node1 keepalived-1.2.4]# vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived

global_defs {

notification_email {

pmghong@163.com

}

notification_email_from pmghong@163.com

smtp_server 192.168.56.120 # node2上改为192.168.56.121

smtp_connect_timeout 30

router_id LVS_DEVEL

}

vrrp_script chk_nginx { # 定义监控脚本

script "/etc/keepalived/checkNginx.sh"

interval 2

weight 2

}

vrrp_instance VI_1 {

state MASTER # node2 修改为BACKUP

interface eth0

virtual_router_id 51

priority 120 # node2上的数值应低于这个值，例如100

advert_int 1

authentication {

auth_type PASS

auth_pass 1111

}

virtual_ipaddress {

192.168.56.130

}

track_script {

# 执行监控脚本，这段代码一定要加！！否则不会调用上面的脚本

chk_nginx

}

2、创建检测脚本

[root@node1 keepalived-1.2.4]# vim /etc/keepalived/checkNginx.sh

#!/bin/bash

#auto check nginx process

killall -0 nginx

if [[ $? -ne 0 ]];then

/etc/init.d/keepalived stop

[root@node1 keepalived-1.2.4]# chmod +x /etc/keepalived/checkNginx.sh

3、启动服务

[root@node1 ~]# service keepalived start

Starting keepalived: [ OK ]

[root@node2 ~]# service keepalived start

Starting keepalived: [ OK ]

[root@node1 ~]# ip addr

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

link/ether 08:00:27:95:99:b7 brd ff:ff:ff:ff:ff:ff

inet 192.168.56.120/24 brd 192.168.56.255 scope global eth0

inet 192.168.56.130/32 scope global eth0

inet6 fe80::a00:27ff:fe95:99b7/64 scope link

valid_lft forever preferred_lft forever

4、测试

(1) 打开浏览器测试访问

关闭node1上的nginx 服务测试效果

PS：网上很多资料在测试这一步，都是停掉node1的keepalived服务，然后测试是否成功。我觉得这样有点不妥，毕竟实际环境中keepalived 停止服务的概率相对于LB和web服务器来说还是很低很低的，这个实验的关键在于，看node1上的nginx由于故障停止服务的时候，node2能否通过keepalived接管负载均衡的功能，并使得网站的访问正常，不间断。所以这里测试应该停的是node1上的nginx，而不是keepalived。

[root@node1 keepalived]# netstat -nultp

Active Internet connections (only servers)

Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name

tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 3786/nginx

[root@node1 keepalived]# kill 3786

(2)找一台不相关的机器长ping VIP

实验结果是只丢了一个包

(3)测试页面访问情况

[root@node2 ~]# ip addr

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

link/ether 08:00:27:7f:4b:aa brd ff:ff:ff:ff:ff:ff

inet 192.168.56.121/24 brd 192.168.56.255 scope global eth0