nginx+keepalived高可用性负载均衡

一、前言

nginx进程基于于Master+Slave(worker)多进程模型，自身具有非常稳定的子进程管理功能。在Master进程分配模式下，Master进程永远不进行业务处理，只是进行任务分发，从而达到Master进程的存活高可靠性，Slave(worker)进程所有的业务信号都由主进程发出，Slave(worker)进程所有的超时任务都会被Master中止，属于非阻塞式任务模型。

Keepalived是Linux下面实现VRRP 备份路由的高可靠性运行件。基于Keepalived设计的服务模式能够真正做到主服务器和备份服务器故障时IP瞬间无缝交接。二者结合，可以构架出比较稳定的软件lb方案。

二、nginx+keepalived架构实战

采用两台服务器做nginx主备，后端采用两个realserver（可以随意扩展），数据库采用mysql主从（这里就不说主从的配置了！）

1、架构图如下：

Server	ip
nginx master	192.168.1.108
nginx backup	192.168.1.110
vip	192.168.1.100
real server1	192.168.1.105
real server2	192.168.1.103

2、安装配置

（1）、安装keepalived（在nginx的mater和backup都安装）

wget http://www.keepalived.org/software/keepalived-1.1.19.tar.gz
tar zxvf keepalived-1.1.19.tar.gz
cd keepalived-1.1.19
./configure --prefix=/usr/local/keepalived
make
make install
cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/
mkdir /etc/keepalived
cd /etc/keepalived/

配置nginx master的keepalived配置文件

[root@zhang1 keepalived]# cat /etc/keepalived/keepalived.conf

bal_defs {

notification_email {

jimo291@gmail.com

}

notification_email_from jimo291@gmail.com

smtp_server 127.0.0.1

smtp_connect_timeout 30

router_id test1

}

vrrp_instance VI_1 {

state MASTER

interface eth0

virtual_router_id 51

priority 100

advert_int 1

smtp_alert

authentication {

auth_type PASS

auth_pass 123

}

virtual_ipaddress {

192.168.1.100

}

配置nginx backup的keepalived配置文件

[root@zhang1 keepalived]# cat /etc/keepalived/keepalived.conf

bal_defs {

notification_email {

jimo291@gmail.com

}

notification_email_from jimo291@gmail.com

smtp_server 127.0.0.1

smtp_connect_timeout 30

router_id test2

}

vrrp_instance VI_1 {

state BACKUP

interface eth0

virtual_router_id 51

priority 80

advert_int 1

smtp_alert

authentication {

auth_type PASS

auth_pass 123

}

virtual_ipaddress {

192.168.1.100

}

启动keepalived！，查看虚拟IP是否绑定！

[root@zhang1 ~]# /etc/rc.d/init.d/keepalived start

Starting keepalived: [ OK ]

[root@zhang1 ~]# ip addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue

link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

inet 127.0.0.1/8 scope host lo

inet6 ::1/128 scope host

valid_lft forever preferred_lft forever

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

link/ether 00:0c:29:65:b4:ed brd ff:ff:ff:ff:ff:ff

inet 192.168.1.108/24 brd 192.168.1.255 scope global eth0

inet 192.168.1.100/32 scope global eth0

inet6 fe80::20c:29ff:fe65:b4ed/64 scope link

valid_lft forever preferred_lft forever

3: eth1: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast qlen 1000

link/ether 00:0c:29:65:b4:f7 brd ff:ff:ff:ff:ff:ff

4: sit0: <NOARP> mtu 1480 qdisc noop

link/sit 0.0.0.0 brd 0.0.0.0

红色部分显示IP已经加载过来了！

3、 nginx的安装和配置

1、创建供Nginx使用的组和帐号：
/usr/sbin/groupadd www -g 48
/usr/sbin/useradd -u 48 -g www www

2、编译安装rewrite模块支持包
wget ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/pcre-7.7.tar.gz
tar zxvf pcre-7.7.tar.gz
cd pcre-7.7/
./configure
make && make install
cd ../

3、编译安装Nginx
wget http://sysoev.ru/nginx/nginx-0.7.64.tar.gz
tar zxvf nginx-0.7.64.tar.gz
cd nginx-0.7.64/
./configure --user=www --group=www --prefix=/usr/local/nginx --with-http_stub_status_module --with-http_ssl_module --with-http_realip_module --with-http_flv_module
make && make install
cd ../

4、备份默认nginx.conf配置文件
mv /usr/local/nginx/conf/nginx.conf /usr/local/nginx/conf/nginx.old

5、配置nginx(两个nginx配置一样！)

[root@linux4 keepalived]# cat /usr/local/nginx/conf/nginx.conf

user www www;

worker_processes 8;

pid /var/run/nginx.pid;

worker_rlimit_nofile 51200;

events

{

use epoll;

worker_connections 5120;

}

http

{

include mime.types;

default_type application/octet-stream;

charset gb2312;

server_names_hash_bucket_size 128;

client_header_buffer_size 32k;

large_client_header_buffers 4 32k;

sendfile on;

tcp_nopush on;

keepalive_timeout 60;

tcp_nodelay on;

gzip on;

gzip_min_length 1k;

gzip_buffers 4 16k;

gzip_http_version 1.0;

gzip_comp_level 2;

gzip_types text/plain application/x-javascript text/css application/xml;

gzip_vary on;

upstream srtweb {

server 192.168.1.105:80;

server 192.168.1.103:80;

}

server {

listen 80;

server_name www.carl.com;

location /{

proxy_pass http://srtweb;

proxy_set_header Host $host;

proxy_set_header X-Real-IP $remote_addr;

proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

}

4、测试

首先单独对nginx测试看是否工作正常，（更改hosts文件来测试！）

其次对keepalived进行测试，停掉nginx master上的keepalived，看backup服务器是否接管！

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