lvs+keepalived+nginx双机主从热备

1.相关名词介绍

1.1 LVS是什么?

      lvs是一个开源的软件,可以实现传输层四层负载均衡。LVS是Linux Virtual Server的缩写,意思是Linux虚拟服务器。 目前有三种IP负载均衡技术(VS/NAT、VS/TUN和VS/DR),linux虚拟机已经自己安装了,无需安装了。

1.2 keepalived是什么?

      LVS可以实现负载均衡,但是不能够进行健康检查, 比如一个rs出现故障,LVS 仍然会把请求转发给故障的rs服务器,这样就会导致请求的无效性。keepalive 软件可以进行健康检查,而且能同时实现 LVS 的高可用性,解决 LVS 单点故障的问题,其实 keepalived 就是为 LVS 而生的。

1.3 nginx常用命令

cd /usr/local/nginx/sbin/
./nginx 开启
./nginx -s stop 强制快速停止或关闭
./nginx -s quit 任务执行完后停止或关闭
./nginx -s reload 重启启动

2.lvs+keepalived+nginx双机主从热备原理图

lvs+keepalived+nginx双机主从热备_第1张图片
流程:(1)客户端发送请求,经过DNS域名解析到虚拟VIP(虚拟ip地址)                    (2)LVS+Keepalived实现负载均衡和故障转移, 配置了主从关系,主nginx不挂掉的话,永远访问主nginx,挂掉的话,就会访问备 nginx

3.lvs+keepalived+nginx双机主从环境搭建

3.1 软件安装

1.下载keepalived

wget http://www.keepalived.org/software/keepalived-1.2.18.tar.gz

2.解压安装:

tar -zxvf keepalived-1.2.18.tar.gz -C /usr/local/

3.下载插件openssl

yum install -y openssl openssl-devel(需要安装一个软件包)

4.开始编译keepalived

cd keepalived-1.2.18/ && ./configure --prefix=/usr/local/keepalived

5.make一下

make && make install

报错: eepalived执行./configure --prefix=/usr/local/keepalived时报错:configure: error: Popt libraries is required
出现此错误的原因:
未安装popt的开发包
解决方法:

yum install popt-devel

安装好popt的开发包。重新./configure 即可。
keepalived安装成Linux系统服务
将keepalived安装成Linux系统服务,因为没有使用keepalived的默认安装路径(默认路径:/usr/local),安装完成之后,需要做一些修改工作:
首先创建文件夹,将keepalived配置文件进行复制:

mkdir /etc/keepalived
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/

然后复制keepalived脚本文件:

cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
ln -s /usr/local/sbin/keepalived /usr/sbin/
ln -s /usr/local/keepalived/sbin/keepalived /sbin/

可以设置开机启动:chkconfig keepalived on,到此我们安装完毕!
keepalived 常用命令
service keepalived start
service keepalived stop

启动报错:Starting keepalived (via systemctl): Job for keepalived.service failed. See ‘systemctl status keepalived.service’ and ‘journalctl -xn’ for details.
解决办法

 cd /usr/sbin/  
 rm -f keepalived   
 cp /usr/local/keepalived/sbin/keepalived  /usr/sbin/

3.2 配置相关文件

每个服务虚拟安装keepalived 虚拟一个VIP ,配置主从关系,当主挂了,直接走备机。
Keepalived虚拟VIP 地址 192.168.223.110
A 服务器 192.168.223.120 主
B 服务器 192.168.223.131 备

修改主keepalived信息
修改主Nginx服务器keepalived文件, /etc/keepalived/keepalived.conf
State 为MASTER

! Configuration File for keepalived

vrrp_script chk_nginx {
    script "/etc/keepalived/nginx_check.sh" #运行脚本,脚本内容下面有,就是起到一个nginx宕机以后,自动开启服务
    interval 2 #检测时间间隔
    weight -20 #如果条件成立的话,则权重 -20
}
# 定义虚拟路由,VI_1 为虚拟路由的标示符,自己定义名称
vrrp_instance VI_1 {
    state MASTER #来决定主从
    interface ens33 # 绑定虚拟 IP 的网络接口,根据自己的机器填写
    virtual_router_id 121 # 虚拟路由的 ID 号, 两个节点设置必须一样
    mcast_src_ip 192.168.223.120 #填写本机ip
    priority 100 # 节点优先级,主要比从节点优先级高
    nopreempt # 优先级高的设置 nopreempt 解决异常恢复后再次抢占的问题
    advert_int 1 # 组播信息发送间隔,两个节点设置必须一样,默认 1s
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    # 将 track_script 块加入 instance 配置块
    track_script {
        chk_nginx #执行 Nginx 监控的服务
    }
    virtual_ipaddress {
        192.168.223.110 # 虚拟ip,也就是解决写死程序的ip怎么能切换的ip,也可扩展,用途广泛。可配置多个。
    }
}

修改从keepalived信息
修改主Nginx服务器keepalived文件, /etc/keepalived/keepalived.conf
State 为BACKUP

! Configuration File for keepalived

vrrp_script chk_nginx {
    script "/etc/keepalived/nginx_check.sh" #运行脚本,脚本内容下面有,就是起到一个nginx宕机以后,自动开启服务
    interval 2 #检测时间间隔
    weight -20 #如果条件成立的话,则权重 -20
}
# 定义虚拟路由,VI_1 为虚拟路由的标示符,自己定义名称
vrrp_instance VI_1 {
    state BACKUP #来决定主从
    interface ens33 # 绑定虚拟 IP 的网络接口,根据自己的机器填写
    virtual_router_id 121 # 虚拟路由的 ID 号, 两个节点设置必须一样
    mcast_src_ip 192.168.223.131 #填写本机ip
    priority 100 # 节点优先级,主要比从节点优先级高
    nopreempt # 优先级高的设置 nopreempt 解决异常恢复后再次抢占的问题
    advert_int 1 # 组播信息发送间隔,两个节点设置必须一样,默认 1s
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    # 将 track_script 块加入 instance 配置块
    track_script {
        chk_nginx #执行 Nginx 监控的服务
    }
    virtual_ipaddress {
        192.168.223.110 # 虚拟ip,也就是解决写死程序的ip怎么能切换的ip,也可扩展,用途广泛。可配置多个。
    }
}

nginx+keepalived实现高可用
写入nginx_check.sh脚本 /etc/keepalived/nginx_check.sh

#!/bin/bash
A=`ps -C nginx –no-header |wc -l`
if [ $A -eq 0 ];then
    /usr/local/nginx/sbin/nginx
    sleep 2
    if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
        killall keepalived
    fi
fi

注意该脚本一定要授权

chmod 777 nginx_check.sh

4.测试lvs+keepalived负载均衡高可用

4.1停掉主机的keepalived

service keepalived stop

访问虚拟vip故障转移,访问的是备机
lvs+keepalived+nginx双机主从热备_第2张图片

4.1重启主机的keepalived

service keepalived start

lvs+keepalived+nginx双机主从热备_第3张图片

你可能感兴趣的:(架构师学习,nginx,LVS,Keepalived,nginx,双机主从热备)