1.案例1--keepalived

1.1 环境

初识keepalived，实现web服务器的高可用集群。
Server1: 192.168.26.144
Server2: 192.168.26.169
VIP: 192.168.26.190

1.2 server1

创建etc下的keepalived目录,编辑配置文件：

# yum -y install keepalived

# vim /etc/keepalived/keepalived.conf

        ! Configuration File for keepalived
        global_defs {
         router_id 1 #设备在组中的标识，设置不一样即可
         }

        #vrrp_script chk_nginx { #健康检查
        # script "/etc/keepalived/ck_ng.sh" #检查脚本
        # interval 2 #检查频率.秒
        # weight -5 #priority减5
        # fall 3 #失败三次
        # }

        vrrp_instance VI_1 { #VI_1。实例名两台路由器相同。同学们要注意区分。
        state MASTER #主或者从状态
        interface ens32 #监控网卡
        mcast_src_ip 192.168.0.118 #心跳源IP
        virtual_router_id 55 #虚拟路由编号，主备要一致。同学们注意区分
        priority 100 #优先级
        advert_int 1 #心跳间隔

        authentication { #秘钥认证(1-8位)
        auth_type PASS
        auth_pass 123456
        }

        virtual_ipaddress { #VIP
        192.168.26.190/24
        }

        # track_script { #引用脚本
        # chk_nginx
        # }

        }

# scp -r /etc/keepalived/keepalived.conf 192.168.26.169:/etc/keepalived/

用scp复制给server2

# systemctl enable keepalived.service
   开机启动keepalived

安装Nginx：

        rpm -ivh http://nginx.org/packages/centos/7/noarch/RPMS/nginx-release-centos-7-0.el7.ngx.noarch.rpm
        yum -y install nginx
        systemctl enable nginx.service
        systemctl start nginx.service
        vim /usr/share/nginx/html/index.html

systemctl start keepalived.service

1.3 server2

BACKUP服务器的配置需要几处修改:

# yum -y install keepalived

# vi /etc/keepalived/keepalived.conf

        router_id 1 改为  router_id 2

        state MASTER改为 state BACKUP
        mcast_src_ip 192.168.26.144改为backup服务器实际的IP mcast_src_ip 192.168.26.169
        priority 100改为priority 99

# systemctl enable keepalived.service

安装Nginx：

        rpm -ivh http://nginx.org/packages/centos/7/noarch/RPMS/nginx-release-centos-7-0.el7.ngx.noarch.rpm
        yum -y install nginx
        systemctl enable nginx.service
        systemctl start nginx.service
        vim /usr/share/nginx/html/index.html

systemctl start keepalived.service

1.4 客户机测试访问

访问VIP http://192.168.26.190
拔掉master的网线。
访问VIP http://192.168.26.190，观察网页已经切换

1.5 关于keepalived对web状态未知的问题

对于上述实验;若maser服务器上的nginx服务出现了问题，此时用户再访问访问服务器是有问题的；

原因是keepalived监控的是接口IP状态。无法监控nginx服务状态

编辑监控脚本:

--server1  添加Nginx监控脚本:

# vim /etc/keepalived/ck_ng.sh

                #!/bin/bash
                #检查nginx进程是否存在
                counter=$(ps -C nginx --no-heading|wc -l)
                if [ "${counter}" = "0" ]; then
                #尝试启动一次nginx，停止5秒后再次检测
                  service nginx start
                  sleep 5
                  counter=$(ps -C nginx --no-heading|wc -l)
                  if [ "${counter}" = "0" ]; then
                #如果启动没成功，就杀掉keepalive触发主备切换
                  service keepalived stop
                  fi
                fi

# chmod +x /etc/keepalived/ck_ng.sh

         --server2 添加Nginx监控脚本:

# vim /etc/keepalived/ck_ng.sh

                #!/bin/bash
                #检查nginx进程是否存在
                counter=$(ps -C nginx --no-heading|wc -l)
                if [ "${counter}" = "0" ]; then
                #尝试启动一次nginx，停止5秒后再次检测
                  service nginx start
                  sleep 5
                  counter=$(ps -C nginx --no-heading|wc -l)
                  if [ "${counter}" = "0" ]; then
                #如果启动没成功，就杀掉keepalive触发主备切换
                  service keepalived stop
                  fi
                fi

# chmod +x /etc/keepalived/ck_ng.sh

启动监控脚本清除掉配置文件中的注释。重启keepalived即可

2.案例2--keepalived + Lvs集群

2.1 环境

keepalived+lvs集群

192.168.0.116 26.144 dr1 负载均衡器 master
192.168.0.117 26.169 dr2 负载均衡器
192.168.0.118 26.165 rs1 web1
192.168.0.119 26.166 rs2 web2

2.2 在master上安装配置Keepalived:

# yum install keepalived ipvsadm -y    ipvsadm安装并不启动

# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
   router_id Director1 #两边不一样。
   }

vrrp_instance VI_1 {
   state MASTER               #另外一台机器是BACKUP
   interface ens33 #心跳网卡
   virtual_router_id 51           #虚拟路由编号，主备要一致
   priority 150               #优先级
   advert_int 1               #检查间隔，单位秒
   authentication {
       auth_type PASS
       auth_pass 1111
       }
   virtual_ipaddress {
       192.168.26.190/24 dev ens33 #VIP和工作接口
       }
   }

virtual_server 192.168.26.190 80 {       #LVS 配置，VIP
   delay_loop 3               #服务论询的时间间隔，#每隔3秒检查一次real_server状态
   lb_algo rr               #LVS 调度算法
   lb_kind DR              #LVS 集群模式
   protocol TCP
   real_server 192.168.26.165 80 {
       weight 1
       TCP_CHECK {
           connect_timeout 3 #健康检查方式,连接超时时间
           }
       }
   real_server 192.168.26.166 80 {
       weight 1
       TCP_CHECK {
           connect_timeout 3
           }
       }
}

2.3 在backup上安装keepalived:

# yum install keepalived ipvsadm -y    ipvsadm安装并不启动

拷贝master上的keepalived.conf到backup上：

        # scp /etc/keepalived/keepalived.conf 192.168.26.169:/etc/keepalived/

拷贝后,修改配置文件：

        router_id Director2
        state BACKUP
        priority 100

2.4 master和backup上启动服务:

#systemctl enable keepalived
# systemctl start keepalived
#reboot

2.5 web服务器配置

web1和web2同配置

安装web测试站点：

        yum install -y httpd && systemctl start httpd && systemctl enable httpd
        netstat -antp | grep httpd
        # elinks 127.0.0.1

        自定义web主页，以便观察负载均衡结果

配置虚拟地址：

        #cp /etc/sysconfig/network-scripts/{ifcfg-lo,ifcfg-lo:0}
        #vim /etc/sysconfig/network-scripts/ifcfg-lo:0
        DEVICE=lo:0
        IPADDR=192.168.0.20
        NETMASK=255.255.255.255
        ONBOOT=yes
        其他行注释掉

配置路由：

        #vim /etc/rc.local
        /sbin/route add -host 192.168.0.20 dev lo:0
        在两台机器（RS）上，添加一个路由：route add -host 192.168.0.20 dev lo:0
        确保如果请求的目标IP是$VIP，那么让出去的数据包的源地址也显示为$VIP

配置ARP：

        # vim /etc/sysctl.conf

        net.ipv4.conf.all.arp_ignore = 1
        net.ipv4.conf.all.arp_announce = 2
        net.ipv4.conf.default.arp_ignore = 1
        net.ipv4.conf.default.arp_announce = 2
        net.ipv4.conf.lo.arp_ignore = 1
        net.ipv4.conf.lo.arp_announce = 2

        忽略arp请求可以回复

        # reboot

2.6 测试：

1）观察lvs路由条目 master上查询 # ipvsadm -L

2）观察vip地址在哪台机器上 master上查询 # ip a

3）客户端浏览器访问vip

4）关闭master上的keepalived服务，再次访问vip
master上关闭 # systemctl stop keepalived.service

5）关闭web1站点服务，再次访问VIP

web1 # systemctl stop httpd