nginx与keepalived实现高可用

准备四台虚拟机，一台master主服务器（安装nginx、keepalived），一台backup从服务器（安装nginx、keepalived），两台Web测试机（安装apache）

对所有虚拟机关闭防火墙和安全机制

[root@localhost ~]# systemctl stop firewalld
[root@localhost ~]# iptables -F
[root@localhost ~]# setenforce 0

一、master主机

1、安装keepalived

[root@localhost ~]# yum -y install keepalived

2、安装nginx

[root@localhost ~]# yum -y install pcre-devel zlib-devel openssl-devel
[root@localhost ~]# yum -y install gcc gcc-c++ make
[root@localhost ~]# useradd -M -s /sbin/nologin nginx
[root@localhost ~]# tar -xf nginx-1.15.9.tar.gz -C /usr/src/
[root@localhost ~]# cd /usr/src/nginx-1.15.9/
[root@localhost ~]# ./configure --prefix=/usr/local/nginx --user=nginx --group=nginx && make && make install
[root@localhost ~]# ln -s /usr/local/nginx/sbin/nginx /usr/local/sbin/
[root@localhost ~]# nginx
[root@localhost ~]# netstat -lnpt | grep :80
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      13144/nginx: master

3、修改nginx的配置文件（实现轮询效果）

[root@localhost ~]# vim /usr/local/nginx/conf/nginx.conf
。。。。。。。。。
upstream httpd1 {
        server 192.168.200.113:80 weight=1;
        server 192.168.200.114:80 weight=1;
    }
server {
        listen       80;
        server_name  localhost;

        charset utf-8;
 location / {
            root   html;
            index  index.html index.htm;
            proxy_pass http://httpd1;
            proxy_set_header Host $host;
        }
。。。。。。。。。。

4、修改keepalived配置文件（实现VIP的转让功能）

[root@localhost ~]# vim /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
}

//引入脚本文件
vrrp_script check_nginx {
   script "/shell/nginx_check.sh"
   interval 2   //等待时间
   weight -20   //权重 ，如果机器出现故障，那么主服务器的优先级会低于从服务器20，那么VIP会自动跳转到副机上
}

vrrp_instance VI_1 {
    state MASTER    //主
    interface eno16777728   //心跳网卡
    virtual_router_id 51
    priority 100   //优先级
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.200.201
    }
    track_script {
    check_nginx    //引用脚本
    }
}

[root@localhost ~]# systemctl restart keepalived

5、编写脚本（配置周期性任务）

[root@localhost ~]# mkdir /shell
[root@localhost ~]# vim /shell/nginx_check.sh
#!/bin/bash
count="$(ps -C nginx --no-header | wc -l)"    //查看nginx运行的进程，去除头部并统计行数
if [ $count -eq 0 ]
then
        /usr/local/nginx/sbin/nginx    //开启nginx
        if [ $count -eq 0]
        then
                systemctl stop keepalived
        fi
fi

6、查看VIP

[root@localhost ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eno16777728: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:9b:5c:f0 brd ff:ff:ff:ff:ff:ff
    inet 192.168.200.111/24 brd 192.168.200.255 scope global eno16777728
       valid_lft forever preferred_lft forever
    inet 192.168.200.201/32 scope global eno16777728
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe9b:5cf0/64 scope link 
       valid_lft forever preferred_lft forever

二、backup主机

1、2、3、5省略，与master的配置相同

4、修改keepalived配置文件

[root@localhost ~]# vim /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
}

vrrp_script check_nginx {
    script "/shell/nginx_check.sh"
    interval 2
    weight -20
}

vrrp_instance VI_1 {
    state BACKUP
    interface eno16777728
    virtual_router_id 51
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.200.201
    }
    track_script {
    check_nginx
    }
}

[root@localhost ~]# systemctl restart keepalived

三、两台测试机安装apache，并编写测试文件

[root@localhost ~]# yum -y install httpd
[root@localhost ~]# systemctl start httpd
[root@localhost ~]# echo "111111" > /var/www/html/index.html  

第二台服务器上编写22222222

四、测试

 如果主服务器的keepalived服务出现故障，VIP会自动跳转到从服务器，如下所示：

####主服务器上######
[root@localhost ~]# systemctl stop keepalived
[root@localhost ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eno16777728: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:9b:5c:f0 brd ff:ff:ff:ff:ff:ff
    inet 192.168.200.111/24 brd 192.168.200.255 scope global eno16777728
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe9b:5cf0/64 scope link 
       valid_lft forever preferred_lft forever

#####从服务器#######
[root@localhost ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eno16777728: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:ec:88:30 brd ff:ff:ff:ff:ff:ff
    inet 192.168.200.112/24 brd 192.168.200.255 scope global eno16777728
       valid_lft forever preferred_lft forever
    inet 192.168.200.201/32 scope global eno16777728
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:feec:8830/64 scope link 
       valid_lft forever preferred_lft forever

将主服务器的keepalived重新打开之后，VIP回到主服务器上

#####主服务器#####
[root@localhost ~]# systemctl start keepalived
[root@localhost ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eno16777728: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:9b:5c:f0 brd ff:ff:ff:ff:ff:ff
    inet 192.168.200.111/24 brd 192.168.200.255 scope global eno16777728
       valid_lft forever preferred_lft forever
    inet 192.168.200.201/32 scope global eno16777728
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe9b:5cf0/64 scope link 
       valid_lft forever preferred_lft forever

#####从服务器#######
[root@localhost ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eno16777728: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:ec:88:30 brd ff:ff:ff:ff:ff:ff
    inet 192.168.200.112/24 brd 192.168.200.255 scope global eno16777728
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:feec:8830/64 scope link 
       valid_lft forever preferred_lft forever