nginx+keepalived7层负载均衡解决方案

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。

现在有两台虚拟机ServerA和ServerB. 两个对外提供Web服务器的虚IP(VIP)192.168.200.100和192.168.200.200, 虚IP用在keepalived的配置中, 网卡接口配置有内网IP.

ServerA:
eth0: 192.168.200.128
VIP: 192.168.200.100 （www.srt.com.cn）

ServerB:
eth0: 192.168.200.129
VIP: 192.168.200.200  （www.srtedu.com）

nginx+keepalived做7层高可用负载均衡方案

如果两台服务器都正常地提供网络服务, 那么, 发往192.168.200.100的服务请求会被ServerA处理, 发往192.168.200.200的服务请求会被ServerB处理. 假设只有ServerB出现故障, 那么, 所有的请求都由ServerA进行处理. 当只有ServerA出现故障时, 也是同理.

软件环境：本文使用的Linux为RHEL 5.2、软件：keepalived-1.1.19、nginx-0.7.64

安装Keepalived

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Keepalived

接下来, 是最重要的修改配置文件/etc/keepalived/keepalived.conf.

global_defs {
         notification_email {
                 baowei@srt.com.cn
         }
         notification_email_from baowei@srt.com.cn
         smtp_server 211.155.225.210
         smtp_connect_timeout 30
         router_id srtweb

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 srt_L7switch
         }
         virtual_ipaddress {
                 192.168.200.100
         }
}

vrrp_instance VI_2 {
         state BACKUP
         interface eth0
         virtual_router_id 52
         priority 50
         advert_int 1
         smtp_alert
         authentication {
                 auth_type PASS
                 auth_pass srt_L7switch
         }
         virtual_ipaddress {
                 192.168.200.200
         }
}

执行 /etc/rc.d/init.d/keepalived start 启动keepalived后, 执行ip a, 你将看到类似的信息:

[root@node1 ~]# ip a
2: eth0:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:01:11:2a brd ff:ff:ff:ff:ff:ff
    inet 192.168.200.128/24 brd 192.168.200.255 scope global eth0
    inet 192.168.200.100/32 scope global eth0
    inet 192.168.200.200/32 scope global eth0
    inet6 fe80::20c:29ff:fe01:112a/64 scope link

可以看到, ServerA的网卡绑定了两个虚IP 192.168.200.100和192.168.200.200, 这时在第3台机器上ping这两个IP, 是可以通的.

然后, 按上面的方法安装ServerB. ServerB的keepalived.conf配置和ServerA基本相同, 但是, 把state MASTER和state BACKUP调换, priority 100和priority 50调换,router_id改为srtedu. 启动ServerB后, 再到ServerA上运行ip a, 你将看到

[root@node1 ~]# ip a
2: eth0:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:01:11:2a brd ff:ff:ff:ff:ff:ff
    inet 192.168.200.128/24 brd 192.168.200.255 scope global eth0
    inet 192.168.200.100/32 scope global eth0
    inet6 fe80::20c:29ff:fe01:112a/64 scope link

192.168.200.200已经不见了, 因为被ServerB使用了, ServerB是这个IP的MASTER, 它有优先使用权. 这样, 两个IP的网络数据分别被两台服务器处理. 现在验证ServerB在出故障的情况, 将ServerB的网线拔掉, 然后在ServerA上执行ip a, 你将看到

[root@node1 ~]# ip a
2: eth0:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:01:11:2a brd ff:ff:ff:ff:ff:ff
    inet 192.168.200.128/24 brd 192.168.200.255 scope global eth0
    inet 192.168.200.100/32 scope global eth0
    inet 192.168.200.200/32 scope global eth0
    inet6 fe80::20c:29ff:fe01:112a/64 scope link

192.168.200.200又被ServerA使用了.

安装Nginx

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、创建Nginx配置文件
#vi /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 51200;
}

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 192.168.200.201:80;
server 192.168.200.202:80;
server 192.168.200.203:80;
}

upstream srtedu {
server 192.168.200.211:80;
server 192.168.200.212:80;
server 192.168.200.213:80;
}

server {
listen 80;
server_name www.srt.com.cn srt.com.cn;

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;
}
access_log /var/log/access_srtweb.log combined;

}

server {
listen 80;
server_name www.srtedu.com srtedu.com;

location /{
proxy_pass http://srtedu;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
access_log /var/log/access_srtedu.log combined;

}

#第1个server同时也作为默认主机

6、启动

ulimit -SHn 102400
/usr/local/nginx/sbin/nginx

7、同样的在Server B上进行1~6步骤的安装配置Nginx操作。

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nginx+keepalived7层负载均衡解决方案

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