nginx负载均衡+keepalived高可用完全配置小结
nginx做负载均衡（无高可用）大致步骤。
1. 前端
nginx安装，pcre安装，具体步骤不解释。
2. 负载配置
A. 默认轮循
在nginx.conf里加入一行
include upstream.conf,然后所有的负载均衡的配置直接在upstream.conf里配置。
# cat upstream.conf
upstream httpservers {
server 192.168.137.10:80 weight=5;
server 192.168.137.20:80 weight=5;
}
server {
listen 80;
server_name 192.168.137.100;
location / {
proxy_pass http://httpservers;
}
}
A. ip_hash 每个请求按访问ip的hash结果分配，这样每个访客固定访问一个后端服务器，可以解决session的问题
# cat upstream.conf
upstream httpservers {
ip_hash;
server 192.168.137.10:80 weight=5;
server 192.168.137.20:80 weight=5;
}
server {
listen 80;
server_name 192.168.137.100;
location / {
proxy_pass http://httpservers;
}
}
nginx做负载均衡（keepalived高可用）
拓扑图
http://s3.运维网.com/wyfs02/M02/43/F0/wKioL1Pe6TPwIllVAAFxc-5xmvQ713.jpg
http://blog.运维网.com/e/u261/themes/default/images/spacer.gif
1. nginx配置（在主备服务器上配置）
upstream httpservers {
ip_hash;
server 192.168.137.10:80 weight=5;
server 192.168.137.20:80 weight=5;
}
server {
listen 80;
server_name 192.168.137.201;
location / {
proxy_pass http://httpservers;
}
}
2. keepalived安装及配置（在主备服务器上配置）
下载：wget http://www.keepalived.org/software/keepalived-1.2.8.tar.gz
解压：tar zxvf keepalived-1.2.8.tar.gz
编译安装： ./configure --prefix=/usr/local/keepalived
make
make install
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d
cp /usr/local/keepalived/sbin/keepalived /sbin/
mkdir -p /etc/keepalived/
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/ (配置文件一定要在这里，让我费了好大的劲)
修改/etc/keepalived/keepalived.conf ,以下分别列出master和backup的配置
+++++++++++++++++++++++++++++++++++++master+++++++++++++++++++++++++++++++++++++++++++
! Configuration File for keepalived
global_defs {
router_id nginx-proxy-ha
}
vrrp_script chk_http_port {
script "/usr/bin/check_nginx.sh"
interval 2
weight 2
}
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 51
priority 200
advert_int 1
authentication {
auth_type PASS
auth_pass 1234
}
track_interface {
eth0
}
track_script {
chk_http_port
}
virtual_ipaddress {
192.168.137.201
}
}
++++++++++++++++++++++++backup++++++++++++++++++++++++++++++++++++++++++++++++++
! Configuration File for keepalived
global_defs {
router_id nginx-proxy-ha
}
vrrp_script chk_http_port {
script "/usr/bin/check_nginx.sh"
interval 2
weight 2
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 51
priority 180
advert_int 1
authentication {
auth_type PASS
auth_pass 1234
}
track_interface {
eth0
}
track_script {
chk_http_port
}
virtual_ipaddress {
192.168.137.201
}
}
以上配置完成之后 启动nginx和keepalived，一定要先启动nginx，然后在启动keepalived。
测试效果：master和backup都启动keepalived和nginx后，默认的虚拟ip是在master上的，在master上kill nginx后，浮动ip会绑定在backup上。
各配置解释：
global_defs {
notification_email {
admin@company.com (这里可以定义多个报警邮箱)
}
notification_email_from alarm@company.com (报警人)
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_script chk_http_port {
script "/opt/tools/bin/check_ng.sh"
interval 2 （检测脚本执行的间隔）
weight 2
}
vrrp_instance VI_1 {
state BACKUP （显示定义为从服务器）
interface eth1 （绑定的网口，该网口即上面提到的两个IP的接口）
virtual_router_id 51 （定义的ID，官方的是 51，主从服务器必须一直）
mcast_src_ip 211.151.138.3（从服务器的IP）
priority 50 （优先级，任意定义，但是一定要比主服务器低）
advert_int 1
authentication {
auth_type PASS
auth_pass 1111 （默认即可）
}
track_script {
chk_http_port （调用检测脚本）
}
virtual_ipaddress {
211.151.137.5 （绑定的虚IP）
}
}
++++++++++++++++++++++check_nginx.sh+++++++++++++++++++++++++++++++++++++++++++++++++
该脚本用来检测nginx状态，一旦nginx退出，则关闭master的 keepalived，此时的backup收到消息会自动切换为master并绑定虚拟ip。该脚本放在/usr/bin下
#!/bin/bash
if [ "$(ps -ef | grep "nginx: master process"| grep -v grep )" == "" ]
then
killall -9keepalived
fi
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