目录
项目架构
一，环境介绍
二，项目部署
在Web服务器上配置Web测试页面
nginx负载均衡配置
配置Nginx_Master
通过vrrp_script实现对集群资源的监控（1>通过killall命令探测服务运行状态）
通过vrrp_script实现对集群资源的监控（2、开发检测nginx存活的shell脚本）
三，项目测试
四，实现不抢占模式
项目架构
Nginx+Keepalived实现高可用
在 Keepalived + Nginx 高可用负载均衡架构中，keepalived 负责实现高可用。它是一个高性能的服务器高可用或者热备解决方案，Keepalived主要来防止服务器单点故障的发生问题，可以通过其与Nginx的配合实现Web服务器端的高可用。使用keepalived可以保证nginx的高可用，他能监控nginx的健康状态，当nginx出现宕机时自动主备切换。
一，环境介绍
| 服务器名称 | IP | 用途 |
| Nginx_Master | 172.16.90.111 | 提供负载均衡 |
| Nginx_Backup | 172.16.90.112 | 提供负载均衡 |
| LVS-DR-VIP | 172.16.90.200 | 网站的VIP地址 |
| Web1服务器 | 172.16.90.113 | 提供Web服务 |
| Web2服务器 | 172.16.90.114 | 提供Web服务 |
二，项目部署
在Web服务器上配置Web测试页面
web01配置：
cd /usr/share/nginx/html/
echo "web test page,`hostname -I`." > index.html
systemctl restart nginx
web02配置同上
nginx负载均衡配置
两台nginx做同样配置
1、安装nginx
yum install http://nginx.org/packages/rhel/7/x86_64/RPMS/nginx-1.10.0-1.el7.ngx.x86_64.rpm2、配置nginx反向代理
[root@nginx_master ~]# cd /etc/nginx/conf.d/
[root@nginx_master conf.d]# mv default.conf{,.bak}
[root@nginx_master conf.d]# vim web.confupstream webpools {server 172.16.90.113;server 172.16.90.114;
}server {location / {proxy_pass http://webpools;index index.html;}
}
3，重启nginx服务，并测试访问nginx
nginx -t
systemctl restart nginx
客户端访问测试负载均衡：
for ((i=1;i<=10;i++)); do curl 172.16.90.111; done配置Nginx_Master
安装keepalived
yum install keepalived -y通过vrrp_script实现对集群资源的监控（1>通过killall命令探测服务运行状态）
配置keepalived
vim /etc/keepalived/keepalived.confvrrp_script chk_nginx {script "killall -0 nginx"#script "</dev/tcp/127.0.0.1/80"#script "if [ -f /var/run/httpd/httpd.pid ];then exit 0;else exit 1;fi"#script "/etc/keepalived/check_nginx.sh"interval 2fall 2rise 1}vrrp_instance VI_1 {state MASTERinterface ens32 //填你对应的网卡名称virtual_router_id 51priority 100advert_int 1authentication {auth_type PASSauth_pass 1111}notify_master "/etc/keepalived/master.sh"notify_backup "/etc/keepalived/backup.sh"notify_fault "/etc/keepalived/fault.sh"track_script{chk_nginx}virtual_ipaddress {172.16.90.200/24 dev ens32}}
相关参数说明：
notify的用法：
notify_master:当当前节点成为master时，通知脚本执行任务(一般用于启动某服务，比如 nginx,haproxy等)
notify_backup:当当前节点成为backup时，通知脚本执行任务(一般用于关闭某服务，比如nginx,haproxy等)
notify_fault：当当前节点出现故障，执行的任务;
根据提供的路径脚本路径，编写提供日志记录的脚本：
vim /etc/keepalived/master.sh
#!/bin/bash
LOGFILE=/etc/keepalived/nginx_state.log
echo "[master]" >> $LOGFILE
date >> $LOGFILEvim /etc/keepalived/backup.sh
#!/bin/bash
LOGFILE=/etc/keepalived/nginx_state.sh
echo "[backup]" >> $LOGFILE
date >> $LOGFILEvim /etc/keepalived/fault.sh
#!/bin/bash
LOGFILE=/etc/keepalived/nginx_state.log
echo "[dault]" >> $LOGFILE
date >> $LOGFILE
给文件赋予执行权限
chmod +x /etc/keepalived/*.shNginx_Backup配置同上
通过vrrp_script实现对集群资源的监控（2、开发检测nginx存活的shell脚本）
vim /etc/keepalived/check_nginx.sh#!/bin/bash
A=`ps -C nginx --no-header |wc -l`
if [ $A -eq 0 ];thensystemctl start nginxsleep 3
if [ `ps -C nginx --no-header |wc -l` -eq 0 ]
thensystemctl stop keepalivedfi
fi
给文件赋予执行权限
chmod +x /etc/keepalived/*.sh配置keepalived
vim /etc/keepalived/keepalived.confvrrp_script chk_nginx {#script "killall -0 nginx"#script "</dev/tcp/127.0.0.1/80"#script "if [ -f /var/run/httpd/httpd.pid ];then exit 0;else exit 1;fi"script "/etc/keepalived/check_nginx.sh"interval 2fall 2rise 1}vrrp_instance VI_1 {state MASTERinterface ens32 //填你对应的网卡名称virtual_router_id 51priority 100advert_int 1authentication {auth_type PASSauth_pass 1111}notify_master "/etc/keepalived/master.sh"notify_backup "/etc/keepalived/backup.sh"notify_fault "/etc/keepalived/fault.sh"track_script{chk_nginx}virtual_ipaddress {172.16.90.200/24 dev ens32}}
Nginx_Backup配置同上
三，项目测试
重启主从调度的nginx和keepalived
[root@nginx_master ~]# systemctl restart nginx keepalived
[root@nginx_backup ~]# systemctl restart nginx keepalivedMaster，Backup都正常，只有Master对外提供服务
[root@nginx_master ~]# ip a | grep "172.16.90.200"
inet 172.16.90.200/24 scope global ens32Master宕机，Backup接替Master对外提供服务
模拟Master的keepalived服务器停止
[root@nginx_master ~]# systemctl stop keepalived.service
此时VIP在Backup上
[root@nginx_backup ~]# ip a | grep "172.16.90.200"
inet 172.16.90.200/24 scope global ens32在客户机上验证是否Backup接管后还能实现负载均衡
for ((i=1;i<=10;i++)); do curl 172.16.90.200; doneMaster恢复正常，Master继续提供服务，Backup停止服务
模拟Master的keepalived服务恢复正常
[root@nginx_master ~]# systemctl start keepalived.service
此时VIP在Master上
[root@nginx_master ~]# ip a | grep "172.16.90.200"
inet 172.16.90.200/24 scope global ens32四，实现不抢占模式
上述主节点一宕机，备节点就会接管，主节点修复好了，又会重新接管服务。服务的切换存在一定的风险和不稳定性，为了避免生产中多次网络抖动，要实现不抢占模式
nopreempt 设置的是高可用集群中的不抢占功能:设置 nopreempt可以实现主节点故障恢复后不再切回到主节点，让服务一直在备用节点下工作， 直到备用节点出现故障才会进行切换。在使用不抢占功能时，在“state” 状态为 “BACKUP” 的节点上设置,而且这个节点的优先级必须高于其他节点
Nginx_Master上
vim /etc/keepalived/keepalived.confvrrp_script chk_nginx {#script "killall -0 nginx"#script "</dev/tcp/127.0.0.1/80"#script "if [ -f /var/run/httpd/httpd.pid ];then exit 0;else exit 1;fi"script "/etc/keepalived/check_nginx.sh"interval 2fall 2rise 1}vrrp_instance VI_1 {state BACKUP //原来的MASTER改为BACKUPinterface ens32 //填你对应的网卡名称virtual_router_id 51priority 100nopreept //添加这行advert_int 1authentication {auth_type PASSauth_pass 1111}notify_master "/etc/keepalived/master.sh"notify_backup "/etc/keepalived/backup.sh"notify_fault "/etc/keepalived/fault.sh"track_script{chk_nginx}virtual_ipaddress {172.16.90.200/24 dev ens32}}
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