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:
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::
valid_lft forever preferred_lft forever
3: eth1: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 00:
4: sit0: <NOARP> mtu 1480 qdisc noop
link/sit
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！