nginx做负载均衡 keepalived.doc

nginx做负载均衡+keepalived

在前面两篇文章中，阿堂就单nginx主机搭建负载均衡环境作了详细介绍。实际上，这样的负载均衡环境还是有问题的，因为只有一台nginx主机作负载均衡，这样就会存在单点的问题，不算是最理想的架构。所以这篇文章中，阿堂就进行了进一步的深入研究探讨，考虑设计了nginx也作负载均衡的架构设计,这里阿堂用到了keepalived来作nginx的负载均衡功能。阿堂的最终的具体web架构考虑设计如下。
Nginx_MASTER:192.168.7.211提供负载均衡
Nginx_SLAVER:192.168.7.218负载均衡备机
Nginx_VIP_TP:192.168.7.219网站的VIP地址(虚拟IP)
Web1server:192.168.7.211提供web服务
Web2server:192.168.7.160提供web服务

原理：
VIP是外网访问的IP地址，通过keepalived设置，以及VRRP将VIP绑定到主机和备机上，通过权重实现控制。当主机挂掉后，keepalived释放对主机的控制，备机接管VIP。
安装Nginx(省略)请参考阿堂的前两篇文章安装Keepalived，让其分别作web及Nginx的HA#wgethttp://www.keepalived.org/software/keepalived-1.1.15.tar.gz#tarzxvfkeepalived-1.1.15.tar.gz#cdkeepalived-1.1.15#./configure--prefix=/usr/local/keepalived#make#makeinstall#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#cp/usr/local/keepalived/etc/keepalived/keepalived.conf/etc/keepalived#cd/etc/keepalived/
设置主备nginx机器上的配置文件内容：

vi/etc/keepalived/keepalived.conf

!ConfigurationFileforkeepalived

global_defs{
notification_email{
[e-mail]
}
[e-mail]
smtp_server127.0.0.1
smtp_connect_timeout30
router_idLVS_DEVEL
}

vrrp_instanceVI_1{
stateMASTER
interfaceeth0
virtual_router_id51
#此处是主Nginx的IP地址.
mcast_src_ip192.168.7.211
#该机的priority(优先)为100
priority100
advert_int1
authentication{
auth_typePASS
auth_pass1111
}
virtual_ipaddress{
192.168.7.219
}
}

前面的结构那里已经规定好了VIP和主备机的IP,所以这里按上面的填。

备机的配置文件:

!ConfigurationFileforkeepalived

global_defs{
notification_email{
[e-mail]
}
[e-mail]
smtp_server127.0.0.1
smtp_connect_timeout30
router_idLVS_DEVEL
}

vrrp_instanceVI_1{
stateSLAVER
interfaceeth0
virtual_router_id51
#此处是备Nginx的IP地址.
mcast_src_ip192.168.7.218
#该机的priority(优先)为99
priority99
advert_int1
authentication{
auth_typePASS
auth_pass1111
}
virtual_ipaddress{
192.168.7.219
}
}

这时候ping192.168.7.219是不通的。
然后在两台机器上分别启动keepal