**Keepalived+Nginx 高可用集群(主从模式)**
集群架构图:

1210730-20190410111156636-1982430025.png

说明:Keepalived机器同样是nginx负载均衡器。
1)实验环境准备(此处都是使用的centos7系统)
# cat /etc/redhat-release 
CentOS Linux release 7.4.1708 (Core)

1210730-20190410105029949-1864664169.png

在所有节点上面进行配置
# systemctl stop firewalld         //关闭防火墙
# sed -i 's/^SELINUX=.*/SELINUX=disabled/' /etc/sysconfig/selinux        //关闭selinux,重启生效
# setenforce 0                //关闭selinux,临时生效
# ntpdate 0.centos.pool.ntp.org    //时间同步
# yum install nginx -y           //安装nginx
2)配置后端web服务器(两台一样)

# echo "`hostname` `ifconfig ens33 |sed -n 's#.*inet \(.*\)netmask.*#\1#p'`" > 
/usr/share/nginx/html/index.html        //准备测试文件,此处是将主机名和ip写到index.html页面中

# vim /etc/nginx/nginx.conf        //编辑配置文件
user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log;
pid /run/nginx.pid;
include /usr/share/nginx/modules/*.conf;
events {
    worker_connections 1024;
}
http {
    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                  '$status $body_bytes_sent "$http_referer" '
                  '"$http_user_agent" "$http_x_forwarded_for"';
    access_log  /var/log/nginx/access.log  main;
    sendfile            on;
    tcp_nopush          on;
    tcp_nodelay         on;
    keepalive_timeout   65;
    types_hash_max_size 2048;
    include             /etc/nginx/mime.types;
    default_type        application/octet-stream;
    include /etc/nginx/conf.d/*.conf;
    server {
        listen       80;
        server_name  www.mtian.org;
        location / {
            root         /usr/share/nginx/html;
        }
    access_log    /var/log/nginx/access.log main;
    }
}

# systemctl start nginx    //启动nginx
# systemctl enable nginx    //加入开机启动

3)配置LB服务器(两台都一样)
# vim /etc/nginx/nginx.conf
user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log;
pid /run/nginx.pid;
include /usr/share/nginx/modules/*.conf;
events {
    worker_connections 1024;
}
http {
    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                  '$status $body_bytes_sent "$http_referer" '
                  '"$http_user_agent" "$http_x_forwarded_for"';
    access_log  /var/log/nginx/access.log  main;
    sendfile            on;
    tcp_nopush          on;
    tcp_nodelay         on;
    keepalive_timeout   65;
    types_hash_max_size 2048;
    include             /etc/nginx/mime.types;
    default_type        application/octet-stream;
    include /etc/nginx/conf.d/*.conf;
    upstream backend {
    server 192.168.1.33:80 weight=1 max_fails=3 fail_timeout=20s;
    server 192.168.1.34:80 weight=1 max_fails=3 fail_timeout=20s;
    }
    server {
        listen       80;
        server_name  www.mtian.org;
        location / {
        proxy_pass http://backend;
        proxy_set_header Host $host:$proxy_port;
        proxy_set_header X-Forwarded-For $remote_addr;
        }
    }
}

# systemctl start nginx     //启动nginx      
# systemctl enable nginx    //加入开机自启动

4)在测试机(192.168.1.35)上面添加host解析,并测试lb集群是否正常。(测试机任意都可以,只要能访问lb节点。)
[root@node01 ~]# cat /etc/hosts
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
192.168.1.32    www.mtian.org
192.168.1.31    www.mtian.org

// 测试时候轮流关闭lb1 和 lb2 节点,关闭后还是能够访问并看到轮循效果即表示 nginx lb集群搭建成功。
[root@node01 ~]# curl www.mtian.org
web01 192.168.1.33  
[root@node01 ~]# curl www.mtian.org
web02 192.168.1.34  
[root@node01 ~]# curl www.mtian.org
web01 192.168.1.33  
[root@node01 ~]# curl www.mtian.org
web02 192.168.1.34  
[root@node01 ~]# curl www.mtian.org
web01 192.168.1.33  
[root@node01 ~]# curl www.mtian.org
web02 192.168.1.34

5)上面步骤成功后开始搭建keepalived,在两台lb节点上面安装keepalived(也可以源码编译安装、此处直接使用yum装)
# yum install keepalived -y
#6)配置 LB-01节点
[root@LB-01 ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {
   notification_email {
    754347404@qq.com
   }
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id LVS_DEVEL
}

vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 51
    priority 150
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
    192.168.1.110/24 dev ens33 label ens33:1
    }
}

[root@LB-01 ~]# systemctl start keepalived     //启动keepalived
[root@LB-01 ~]# systemctl enable keepalived    //加入开机自启动

[root@LB-01 ~]# ip a    //查看IP,会发现多出了VIP 192.168.1.110
......
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:94:17:44 brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.31/24 brd 192.168.1.255 scope global ens33
       valid_lft forever preferred_lft forever
    inet 192.168.1.110/24 scope global secondary ens33:1
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe94:1744/64 scope link 
       valid_lft forever preferred_lft forever
......   
7)配置 LB-02节点
[root@LB-02 ~]# vim /etc/keepalived/keepalived.conf 
! Configuration File for keepalived

global_defs {
   notification_email {
    754347404@qq.com
}
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id LVS_DEVEL
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
    192.168.1.110/24 dev ens33 label ens33:1
    }
}
[root@LB-02 ~]# systemctl start keepalived        //启动keepalived
[root@LB-02 ~]# systemctl enable keepalived    //加入开机自启动

[root@LB-02 ~]# ifconfig   //查看IP,此时备节点不会有VIP(只有当主挂了的时候,VIP才会飘到备节点)
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.32  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::20c:29ff:feab:6532  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:ab:65:32  txqueuelen 1000  (Ethernet)
        RX packets 43752  bytes 17739987 (16.9 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 4177  bytes 415805 (406.0 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
......

8)在测试机器上面访问 Keepalived上面配置的VIP 192.168.1.110
[root@node01 ~]# curl 192.168.1.110
web01 192.168.1.33  
[root@node01 ~]# curl 192.168.1.110
web02 192.168.1.34  
[root@node01 ~]# curl 192.168.1.110
web01 192.168.1.33  
[root@node01 ~]# curl 192.168.1.110
web02 192.168.1.34

//关闭LB-01 节点上面keepalived主节点。再次访问
[root@LB-01 ~]# systemctl stop keepalived
[root@node01 ~]# 
[root@node01 ~]# curl 192.168.1.110
web01 192.168.1.33  
[root@node01 ~]# curl 192.168.1.110
web02 192.168.1.34  
[root@node01 ~]# curl 192.168.1.110
web01 192.168.1.33  
[root@node01 ~]# curl 192.168.1.110
web02 192.168.1.34

//此时查看LB-01 主节点上面的IP ,发现已经没有了 VIP
[root@LB-01 ~]# ifconfig 
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.31  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::20c:29ff:fe94:1744  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:94:17:44  txqueuelen 1000  (Ethernet)
        RX packets 46813  bytes 18033403 (17.1 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 9350  bytes 1040882 (1016.4 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
...

//查看LB-02 备节点上面的IP,发现 VIP已经成功飘过来了
 [root@LB-02 ~]# ifconfig 
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.32  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::20c:29ff:feab:6532  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:ab:65:32  txqueuelen 1000  (Ethernet)
        RX packets 44023  bytes 17760070 (16.9 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 4333  bytes 430037 (419.9 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

ens33:1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.110  netmask 255.255.255.0  broadcast 0.0.0.0
        ether 00:0c:29:ab:65:32  txqueuelen 1000  (Ethernet)
...