keepalived高可用安装
1）环境准备

主机名	角色	外网ip
lb01	keepalived-master	eth0:10.0.0.5
lb01	keepalived-slave	eth0:10.0.0.6

2）在lb01和lb02上分别安装keepalived

[root@lb01 ~]# yum install -y keepalived
[root@lb02 ~]# yum install -y keepalived

3）keepalived工作原理

• vrrp 虚拟路由冗余协议 诞生是为公司网站网络设备做高可用 3层路由

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4）keepalived文件详解

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配置keepalived

手动测试添加ip地址

ip addr add 10.0.0.3/24 dev eth0:1

ip addr del 10.0.0.3/24 dev eth0:1

lb01（主）配置如下

[root@lb01 ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
    router_id lb01  #主备不能一样
}
vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 150
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
     10.0.0.3/24 dev eth0 label eth0:1
     #10.0.0.3/24   直接写ip，需要手动添加10.0.0.3（vip）
    }
}

lb02(备)配置如下

[root@lb02 ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
    router_id lb02   #主备不能一样
}
vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
     10.0.0.3/24 dev eth0 label eth0:1
    }
}

测试
lb01 lb02操作如下
1）重启keepalived

systemctl restart keepalived

1. lb01检查是否有vip

[root@lb01 ~]# ip a|grep 0.3                                                           inet 10.0.0.3/24 scope global secondary eth0:1

3）lb02检查是否有vip

[root@lb02 ~]# ip a|grep 0.3                                                                                        
[root@lb02 ~]# 

4）关闭lb01的keepalived

systemctl stop keepalived

5 ) lb01检查是否有vip

[root@lb01 ~]# ip a|grep 0.3                                                                                        
[root@lb01 ~]# 

6）lb02检查是否有vip

[root@lb02 ~]# ip a|grep 0.3                                                                                        
    inet 10.0.0.3/24 scope global secondary eth0:1

总结

当keepalived出故障和断网的时候自动切换到备用负载均衡。keepalived基于服务器，nginx挂了 不会自动切换。下面我们需要解决这件事

keepalived随着nginx关闭而关闭

1.解决什么问题？
1）keepalived基于服务器，nginx挂了 不会自动切换
lb01 lb02操作如下
2.写脚本--lb01 lb02都要写--监视nginx,当nginx被关闭后自动关闭keepalived

[root@lb01 ~]# vim /server/scripts/chk.sh
#!/bin/bash
##脚本:检查nginx是否运行 如果不运行 关闭keepalived
#检查进程数量
count=`ps -ef |grep -c '[n]ginx'`  
#检查端口数量
#count=ss -lntup |grep nginx
#count=ps -ef |grep nginx|grep -v grep
#count=ss -lntup |grep -c  nginx 
#检查端口
#count=lsof -i:80
if [ $count -eq 0 ];then
   systemctl stop keepalived
fi

3.配置keepalived配置文件
lb01操作如下

! Configuration File for keepalived

global_defs {
    router_id lb01
}
vrrp_script chk_lb {
script "/server/scripts/chk.sh"
interval 2
weight 1
}

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 150
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
     10.0.0.3/24 dev eth0 label eth0:1
    }
    track_script {
     chk_lb
     }
}

lb02配置如下

[root@lb02 ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {
    router_id lb01
}
vrrp_script chk_lb {
script "/server/scripts/chk.sh"
interval 2
weight 1
}

vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
     10.0.0.3/24 dev eth0 label eth0:1
    }
    track_script {
    chk_lb
    }

启动高可用和负载均衡服务
1）启动nginx keepalived

systemctl restart nginx  keepalived

2）检查进程---是否启动

[root@lb01 ~]# ps -ef|grep nginx
root       7979      1  0 15:31 ?        00:00:00 nginx: master process /usr/sbin/nginx -c /etc/nginx/nginx.conf
nginx      7980   7979  0 15:31 ?        00:00:00 nginx: worker process
root       8011   7219  0 15:32 pts/0    00:00:00 grep --color=auto nginx
[root@lb01 ~]# ps -ef|grep keepalived
root       7982      1  0 15:31 ?        00:00:00 /usr/sbin/keepalived -D
root       7983   7982  0 15:31 ?        00:00:00 /usr/sbin/keepalived -D
root       7984   7982  0 15:31 ?        00:00:00 /usr/sbin/keepalived -D
root       8033   7219  0 15:32 pts/0    00:00:00 grep --color=auto keepalived

3)检查是否有vip

[root@lb01 ~]# ip a|grep 0.3
    inet 10.0.0.3/24 scope global secondary eth0:1  ##ip现在是在lb01上的
[root@lb02 ~]# ip a|grep 0.3
[root@lb02 ~]# 

测试
1）关闭lb01上的nginx,并检查进程

[root@lb01 ~]# systemctl stop nginx
[root@lb01 ~]# ps -ef|grep nginx
root       8931   7219  0 15:38 pts/0    00:00:00 grep --color=auto nginx
[root@lb01 ~]# ps -ef|grep keepalived
root       8933   7219  0 15:38 pts/0    00:00:00 grep --color=auto keepalived
[root@lb01 ~]# ip a|grep 0.3
[root@lb01 ~]# 

2）lb02检查

[root@lb02 ~]# ip a|grep 0.3
    inet 10.0.0.3/24 scope global secondary eth0:1

总结

写个监控nginx服务的脚本，然后在keepalived中使用。这样就可以当nginx出现故障的时候，就关闭keepalived.实现高可用。

keepalived双主模式

解决了什么问题
1）一台主一台备用，只有主故障了以后才会访问备的。这就导致主，压力太大。备压力太小。所有我们需要让他们互为主备。
修改配置文件
lb01配置如下

! Configuration File for keepalived
global_defs {
    router_id lb01
}
vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
     10.0.0.3/24 dev eth0 label eth0:1
    }
}
vrrp_instance VI_2 {
    state MASTER
    interface eth0
    virtual_router_id 52
    priority 150
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
     10.0.0.4/24 dev eth0 label eth0:2 
    }
}

lb02配置如下

! Configuration File for keepalived

global_defs {
    router_id lb01
}
vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 150
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
     10.0.0.3/24 dev eth0 label eth0:1
    }
}
vrrp_instance VI_2 {
    state BACKUP
    interface eth0
    virtual_router_id 52
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
     10.0.0.4/24 dev eth0 label eth0:2 
    }
}

测试双主模式

systemctl restart keepalived       ##重启keepalived
[root@lb01 ~]# ip a|egrep '0.3|0.4'   ##检查lb01 vip
    inet 10.0.0.3/24 scope global secondary eth0:1
[root@lb02 ~]# ip a|egrep '0.3|0.4'   ##检查lb02 vip
    inet 10.0.0.4/24 scope global secondary eth0:2
[root@lb02 ~]# systemctl stop keepalived   ##关闭lb02的高可用后
[root@lb02 ~]# ip a|egrep '0.3|0.4'        ##lb02的vip 已经不存在了
[root@lb02 ~]# 
[root@lb01 ~]# ip a|egrep '0.3|0.4'         ##全都跑到了lb01上来了
    inet 10.0.0.3/24 scope global secondary eth0:1
    inet 10.0.0.4/24 scope global secondary eth0:2

每个域名绑定对应ip
修改配置文件
lb01 lb02都一样

   upstream web_pools {
##  server 10.0.0.7:80 weight=1 max_fails=3 fail_timeout=10s;
##  server 10.0.0.8:80 weight=1 max_fails=3 fail_timeout=10s;
# ip_hash;#加上他用户第一次访问哪台服务器以后就会一直访问那台
    server 10.0.0.7:80 weight=1 max_fails=3 fail_timeout=10s;
    server 10.0.0.8:80 weight=1 max_fails=3 fail_timeout=10s;
    }
   server {
     listen      10.0.0.3:80;
     server_name  www.oldboy.com;
     location / {
        proxy_pass http://web_pools;
       proxy_set_header Host $host;
       proxy_set_header X-Forwarded-For $remote_addr;
  }
  }

    server {
    listen       10.0.0.4:80;
    server_name  blog.oldboy.com;
    location / {
        proxy_pass http://web_pools;
       proxy_set_header Host $http_host;
       proxy_set_header X-Forwarded-For $remote_addr;
    }
   }

检查语法却报错

##nginx: [emerg] bind() to 10.0.0.4:80 failed (99: Cannot assign requested address)
                 把这个10.0.0.4的ip绑定到这台机器 失败了
nginx无法把本地不存在的ip地址进行绑定

修改内核信息

/etc/sysctl.conf  
net.ipv4.ip_nonlocal_bind = 1

#生效
sysctl -p
等于修改这个文件
[root@lb01 ~]# cat /proc/sys/net/ipv4/ip_nonlocal_bind 
1

然后就可以重启成功了，关于ip的变动需要使用restart 重启