Keepalived+Nginx 高可用(主从模式)
1. 环境说明
| vip | ip | 操作系统 | nginx端口 | 主从说明 |
| 192.168.115.150 | 192.168.115.148 | CentOS Linux release 7.6.1810 (Core) | 8443 | 主节点 |
| 192.168.115.150 | 192.168.115.149 | CentOS Linux release 7.6.1810 (Core) | 8443 | 从节点 |
2台机器都需部署nginx和keealive服务，nginx配置文件保持一致，keepalive服务配置存在差异
2. 部署nginx
3. 部署keepalive
3.1 安装
1、下载 wget https://www.keepalived.org/software/keepalived-2.2.2.tar.gz 2、解压 tar -zxvf keepalived-2.2.2.tar.gz 3、安装依赖 yum -y install libnl libnl-devel 否则，会报错编译会报错：*** WARNING - this build will not support IPVS with IPv6. Please install libnl/libnl-3 dev libraries to support IPv6 with IPVS. 4、编译安装 cd keepalived-2.2.2 ./configure --prefix=/usr/local/keepalived make && make install
3.2 修改配置
1、修改keepalive配置
cp -raf /usr/local/keepalived/etc/keepalived/keepalived.conf /usr/local/keepalived/etc/keepalived/keepalived.conf_default vim /usr/local/keepalived/etc/keepalived/keepalived.conf
主节点192.168.115.148和从节点192.168.115.149存在差异，具体配置文件如下：
主节点192.168.115.148：/usr/local/keepalived/etc/keepalived/keepalived.conf配置如下：
global_defs {
router_id Nginx_01
script_user root
}
vrrp_script check_nginx {
script "/usr/local/nginx/keepalived/check_nginx.sh" #nginx检测脚本
interval 2
weight -5
fall 3
rise 2
}
vrrp_instance VI_1 {
state MASTER
interface ens192 #指定HA监测网络的接口。与本机 IP 地址所在的网络接口相同，可通过ip addr 查看
virtual_router_id 33 #虚拟路由标识，这个标识是一个数字，同一个vrrp实例使用唯一的标识。即同一vrrp_instance下，MASTER和BACKUP必须是一致
priority 100 #定义优先级，数字越大，优先级越高，在同一个vrrp_instance下，MASTER的优先级必须大于BACKUP的优先级
advert_int 1
authentication { #设置验证类型和密码。主从必须一样
auth_type PASS #设置vrrp验证类型，主要有PASS和AH两种
auth_pass 1111 #设置vrrp验证密码，在同一个vrrp_instance下，MASTER与BACKUP必须使用相同的密码才能正常通信
}
virtual_ipaddress { #VRRP HA 虚拟地址 如果有多个VIP，继续换行填写
192.168.115.150
}
track_script {
check_nginx
}
}
从节点192.168.115.149：/usr/local/keepalived/etc/keepalived/keepalived.conf配置如下：
global_defs {
script_user root
router_id Nginx_02
}
vrrp_script check_nginx {
script "/usr/local/nginx/keepalived/check_nginx.sh"
interval 2
weight -5
fall 3
rise 2
}
vrrp_instance VI_1 {
state BACKUP
interface ens192
virtual_router_id 33
priority 50
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.115.150
}
track_script {
check_nginx
}
}
2、新建nginx检测脚本
vim /usr/local/nginx/keepalived/check_nginx.sh chmod +x /usr/local/nginx/keepalived/check_nginx.sh
主从节点192.168.115.148/149 nginx检测脚本一致，/usr/local/nginx/keepalived/check_nginx.sh配置文件如下：
! /bin/bash pidof nginx if [ $? -ne 0 ];then systemctl stop keepalived fi
3.3 启动
#开机自启动 systemctl enable keepalived #查看状态 systemctl status keepalived #启动 systemctl start keepalived #加载配置 systemctl daemon-reload #重启 systemctl restart keepalived
3.4 特殊说明
如未遇到以下情况，忽略即可
1、启动问题
直接启动如果报错，可能是systemctl管理未指定配置文件，修改配置systemctl自启动文件，重新加载配置文件并重新启动keepalive
vim /usr/lib/systemd/system/keepalived.service
[Unit] Description=LVS and VRRP High Availability Monitor After=network-online.target syslog.target Wants=network-online.target [Service] Type=forking PIDFile=/run/keepalived.pid KillMode=process EnvironmentFile=-/usr/local/keepalived/etc/sysconfig/keepalived #ExecStart=/usr/local/keepalived/sbin/keepalived $KEEPALIVED_OPTIONS ##注释默认 ExecStart=/usr/local/keepalived/sbin/keepalived -f /usr/local/keepalived/etc/keepalived/keepalived.conf ##指定配置文件 ExecReload=/bin/kill -HUP $MAINPID [Install] WantedBy=multi-user.target
2、防火墙配置
主从节点启动keepalived之后, 正常情况下vip只在主节点上存在，而从节点在主节点故障时接管VIP。
如果发现VIP在两个节点上同时存在，要配置防火墙以防止VIP在两个节点上同时存在，需要确保VRRP协议能够在两个节点间正常通信
#允许VRRP协议通过防火墙 firewall-cmd --add-rich-rule='rule protocol value="vrrp" accept' --permanent #重新加载 firewalld firewall-cmd --reload
4. 高可用测试
1、主从2个节点分别先启动nginx服务再keepalived服务，确保vip只在主节点上存在
2、模拟主节点nginx服务停止：停止nginx服务
检查主节点keepalived和vip情况，正常情况为：主节点keepalived停止，vip漂移到从节点，流量转移到从节点
3、模拟主节点nginx服务恢复：启动nginx服务和keepalived服务
检查vip情况，正常情况为：vip漂移到主节点，流量转移到主节点，从节点恢复空间状态
