Keepalived概念

解决单点故障

组件免费

可以实现高可用HA机制

基于VRRP协议

虚拟路由冗余协议VRRP

Virtual Router Redundancy Protocol

解决内网单机故障的路由协议

构建有多个路由器MASTER BACKUP

虚拟IP - VIP（Virtual IP Address）

Keepalived安装部署

1.下载地址：Keepalived for Linux

2.通过ftp工具上传到linux中，/home/software

3.解压

tar -zxvf keepalived-2.2.4.tar.gz

4.解压后进入到解压出来的目录，看到会有configure，那么就可以做配置了（配置安装和nginx一模一样）

5.使用configure命令配置安装目录与核心配置文件所在位置：

./configure --prefix=/usr/local/keepalived --sysconf=/etc

prefix：keepalived安装的位置

sysconf：keepalived核心配置文件所在位置，固定位置，改成其他位置则keepalived启动不了，/var/log/messages中会报错

5.1 配置过程中可能会出现警告信息，如下所示：

*** WARNING - this build will not support IPVS with IPv6. Please install libnl/libnl-3 dev libraries to support IPv6 with IPVS.

5.2 安装libnl、libnl-3依赖

yum -y install libnl libnl-devel  

5.3 重新configure一下，此时OK。

6.安装keepalived

# 两种方式都可以：

# 第一种 
make && make install

# 第二种
# 编译
make 

# 安装
make install

7.进入到/etc/keepalived,该目录下为keepalived核心配置文件

 如果忘记安装配置的目录，则通过如下命令找到：

Keepalived配置-主Master

1.通过命令vim keepalived.conf打开配置文件

global_defs {
   # 路由id：当前安装keepalived的节点主机标识符，保证全局唯一
   router_id keep_171
}

vrrp_instance VI_1 {
    # 表示状态是MASTER主机还是备用机BACKUP
    state MASTER
    # 该实例绑定的网卡
    interface ens0
    # 保证主备节点一致即可
    virtual_router_id 51
    # 权重，master权重一般高于backup，如果有多个，那就是选举，谁的权重高，谁就当选
    priority 100
    # 主备之间同步检查时间间隔，单位秒
    advert_int 2
    # 认证权限密码，防止非法节点进入
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    # 虚拟出来的ip，可以有多个（v_ip）
    virtual_ipaddress {
        192.168.1.100
    }
}

查看网卡名称命令: ifconfig

2.启动Keepalived

在sbin目录中进行启动（同nginx），如下图：

3.查看进程

ps -ef | grep keepalived

4.查看ip

在网卡ens0下，多了一个192.168.1.100，这个就是虚拟v_ip。

 Keepalived配置-备Backup

1.通过命令 vim keepalived.conf 打开配置文件

global_defs {
   router_id keep_172
}

vrrp_instance VI_1 {
    # 备用机设置为BACKUP
    state BACKUP
    interface ens0
    virtual_router_id 51
    # 权重低于MASTER
    priority 80
    advert_int 2
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        # 注意：主备两台的v_ip都是一样的，绑定到同一个v_ip
        192.168.1.100
    }
}

2.启动Keepalived

# 启动keepalived
systemctl start keepalived
# 停止keepalived
systemctl stop keepalived
# 重启keepalived
systemctl restart keepalived

3.查看进程

ps -ef|grep keepalived

Kepalived配置Nginx自动重启

1.增加Nginx重启检测脚本

vim /etc/keepalived/check_nginx_alive_or_not.sh

#!/bin/bash

A=`ps -C nginx --no-header |wc -l`
# 判断nginx是否宕机，如果宕机了，尝试重启
if [ $A -eq 0 ];then
    /usr/local/nginx/sbin/nginx
    # 等待一小会再次检查nginx，如果没有启动成功，则停止keepalived，使其启动备用机
    sleep 3
    if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
        killall keepalived
    fi
fi

增加权限命令：chmod +x /etc/keepalived/check_nginx_alive_or_not.sh

2.配置keepalived监听nginx脚本，keepalived.conf文件中

vrrp_script check_nginx_alive {
    script "/etc/keepalived/check_nginx_alive_or_not.sh"
    interval 2 # 每隔两秒运行上一行脚本
    weight 10 # 如果脚本运行成功，则升级权重+10
    # weight -10 # 如果脚本运行失败，则升级权重-10
}

3.在vrrp_instance中新增监控的脚本

track_script {
    check_nginx_alive   # 追踪 nginx 脚本
}

4.重启Keepalived使得配置文件生效

systemctl restart keepalived

Keepalived配置双主热备

规则：以一个虚拟ip分组归为同一个路由

主节点配置：

global_defs {
   router_id keep_171
}

vrrp_instance VI_1 {
    state MASTER
    interface ens0
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.100
    }
}

vrrp_instance VI_2 {
    state BACKUP
    interface ens0
    virtual_router_id 52
    priority 80
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.101
    }
}

备用节点配置：

global_defs {
   router_id keep_172
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens0
    virtual_router_id 51
    priority 80
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.100
    }
}

vrrp_instance VI_2 {
    state MASTER
    interface ens0
    virtual_router_id 52
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.101
    }
}

注意：分别重启两条Keepalived

# 重启Keepalived
systemctl restart keepalived