前提说明:
此篇文章纯粹是部署操作，有关nginx负载均衡及keepalived原理不做阐述
环境准备
1.两台centos机器或者虚拟机
2.三个ip，两台机器各有一个，第三个作为虚拟ip在两台机器上根据服务状态动态切换
一、nginx安装配置(主备机器过程相同)
1.配置nginx yum安装源
新建/etc/yum.repos.d/nginx.repo,添加如下内容
[nginx-stable]
name=nginx stable repo
baseurl=http://nginx.org/packages/centos/$releasever/$basearch/
gpgcheck=1
enabled=1
gpgkey=https://nginx.org/keys/nginx_signing.key
module_hotfixes=true
[nginx-mainline]
name=nginx mainline repo
baseurl=http://nginx.org/packages/mainline/centos/$releasever/$basearch/
gpgcheck=1
enabled=0
gpgkey=https://nginx.org/keys/nginx_signing.key
module_hotfixes=true
2.执行安装
yum install nginx
3.加入开机自启
systemctl enable nginx
4.配置
新建/etc/nginx/conf.d/sys.conf，添加代理配置，负载均衡策略采用ip_hash
#upstream要与proxy_pass对应你
upstream sys {
ip_hash;
server 192.168.1.100:8280;
server 192.168.1.101:8280;
}
#为了查看请求到底代理到哪台服务器上了，特添加日志特殊格式
log_format upstream '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for"'
'$upstream_addr $upstream_response_time $request_time ';
access_log /var/log/nginx/odm.access.log upstream;
server {
listen 80;
server_name localhost;
client_header_buffer_size 16k;
large_client_header_buffers 4 64k;
client_max_body_size 15m;
proxy_connect_timeout 600s;
proxy_send_timeout 600s;
proxy_read_timeout 600s;
proxy_buffer_size 128k;
proxy_buffers 16 128k;
proxy_busy_buffers_size 128k;
proxy_temp_file_write_size 128k;
#proxy_pass 配置要与upstream配置对应
location /sys {
proxy_pass http://sys;
proxy_redirect off ;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header REMOTE-HOST $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root /usr/share/nginx/html;
}
}
5.启动
systemctl start nginx
6.查看服务状态
systemctl status nginx
7.关闭防火墙
systemctl stop firewalld.service
8.访问应用进行验证
二、keepalived安装配置（主备机器安装过程相同，配置差别只体现在第4步）
1.安装
yum install keepalived
2.加入开机启动
systemctl enable keepalived
3.编写nginx监控脚本
（1）新建/etc/keepalived/nginx_check.sh 添加内容
#!/bin/bash
counter=$(ps -C nginx --no-heading|wc -l)
if [ "${counter}" = "0" ]; then
systemctl start nginx
sleep 2
counter=$(ps -C nginx --no-heading|wc -l)
if [ "${counter}" = "0" ]; then
systemctl stop keepalived.service
fi
fi
(2) 为脚本添加执行权限
chmod +x nginx_check.sh
4.keepalived抢占式配置配置
(1) master配置：vi /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
# notification_email {
# acassen@firewall.loc
# failover@firewall.loc
# sysadmin@firewall.loc
# }
# notification_email_from Alexandre.Cassen@firewall.loc
# smtp_server 192.168.200.1
# smtp_connect_timeout 30
router_id LVS_DEVEL #标识信息,一个名字而已
# vrrp_skip_check_adv_addr
# vrrp_strict
# vrrp_garp_interval 0
# vrrp_gna_interval 0
}
# 定义nginx监控脚本
vrrp_script chk_nginx {
script "/etc/keepalived/nginx_check.sh"
interval 2 #执行间隔
weight -20 #根据脚本执行结果调整weight权重
}
vrrp_instance VI_1 {
state MASTER #角色MASTER
interface eth0 #虚拟IP绑定网口 通过ip a可查看
virtual_router_id 51 #让master 和backup在同一个虚拟路由里，id 号必须相同
priority 100 #优先级 master要高于backup
advert_int 1 #心跳间隔
authentication {
auth_type PASS #认证方式，可以是PASS或AH两种认证方式
auth_pass 1111 #认证密码
}
track_script {
chk_nginx ## nginx监控脚本
}
virtual_ipaddress {
172.31.4.14 ## 虚拟ip
}
}
(2) backup配置：vi /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
# notification_email {
# acassen@firewall.loc
# failover@firewall.loc
# sysadmin@firewall.loc
# }
# notification_email_from Alexandre.Cassen@firewall.loc
# smtp_server 192.168.200.1
# smtp_connect_timeout 30
router_id dreamerl #标识信息，不要与master相同
# vrrp_skip_check_adv_addr
# vrrp_strict
# vrrp_garp_interval 0
# vrrp_gna_interval 0
}
# 定义nginx监控脚本
vrrp_script chk_nginx {
script "/etc/keepalived/nginx_check.sh"
interval 2 #执行间隔
weight -20 #根据脚本执行结果调整weight权重
}
vrrp_instance VI_1 {
state BACKUP #角色BACKUP
interface eth0 #虚拟IP绑定网口 通过ip a可查看
virtual_router_id 51 #让master 和backup在同一个虚拟路由里，id 号必须相同
priority 90 #优先级 backup要低于master
advert_int 1 #心跳间隔
authentication {
auth_type PASS #认证方式，可以是PASS或AH两种认证方式
auth_pass 1111 #认证密码
}
track_script {
chk_nginx ## nginx监控脚本
}
virtual_ipaddress {
172.31.4.14 ## 虚拟ip
}
}
5.启动
systemctl start keepalived
6.验证
master上执行
ip a
正常情况下会发现虚拟ip挂载在master对应网卡上
ip a.png
master上执行
systemctl stop keepalived
停掉keepalived服务
backup上执行
ip a
正常情况虚拟ip已切换到backup机器上
