在CentOS7上部署Memcached主主复制+Keepalived高可用架构

原理：

Memcached主主复制是指在任意一台Memcached服务器修改数据都会被同步到另外一台，但是Memcached API客户端是无法判断连接到哪一台Memcached服务器的，所以需要设置VIP地址，提供给Memcached API客户端进行连接。可以使用Keepalived产生的VIP地址连接主Memcached服务器，并且提供高可用架构。

使用两台Memcached服务器，一台客户机来完成，实验环境表如下：

1.配置memcached主缓存节点和从缓存节点—–两台配置相同

 [[email protected] ~]# tar zxvf libevent-2.1.8-stable.tar.gz -C /opt/   //解包//   [[email protected] ~]# tar zxvf memcached-1.5.6.tar.gz -C /opt/   [[email protected] ~]# mkdir /opt/magent   [[email protected] ~]# tar zxvf magent-0.5.tar.gz -C /opt/magent/   [[email protected] opt]#cd libevent-2.1.8-stable/   [[email protected] libevent-2.1.8-stable]# yum install gcc gcc-c++ make -y   [[email protected] libevent-2.1.8-stable]# ./configure --prefix=/usr   [[email protected] libevent-2.1.8-stable]# make && make install   [[email protected] libevent-2.1.8-stable]# cd ../memcached-1.5.6/   [[email protected] memcached-1.5.6]# ./configure --with-libevent=/usr     [[email protected] memcached-1.5.6]# ln -s /usr/lib/libevent-2.1.so.6 /usr/lib64/libevent-2.1.so.6    //软链接//  

2.关闭防火墙并开启memcached服务

[[email protected] memcached-1.5.6]# systemctl stop firewalld.service  [[email protected] memcached-1.5.6]# setenforce 0  [[email protected] memcached-1.5.6]# memcached -d -m 32m -p 11211 -u root  [[email protected] memcached-1.5.6]# netstat -ntap | grep 11211  tcp        0      0 0.0.0.0:11211           0.0.0.0:*               LISTEN      11224/memcached  tcp6       0      0 :::11211                :::*                    LISTEN      11224/memcached  

3.在主服务器上安装magent

[[email protected] memcached-1.5.6]# cd /opt/magent/  [[email protected] magent]# ls  ketama.c  ketama.h  magent.c  Makefile  [[email protected] magent]# vim ketama.h    #ifndef SSIZE_MAX  #define SSIZE_MAX 32767  #endif  [[email protected] magent]# vim Makefile  LIBS = -levent -lm //第一行末尾加-lm （不是数字1  LIBS = -levent -lm  CFLAGS = -Wall -O2 -g    [[email protected] magent]# make  gcc -Wall -O2 -g  -c -o magent.o magent.c  gcc -Wall -O2 -g  -c -o ketama.o ketama.c  gcc -Wall -O2 -g -o magent magent.o ketama.o -levent -lm  

4.把生成的mgent程序让系统识别

ls一下可看到magent可执行程序  [[email protected] magent]# ls  ketama.c  ketama.h  ketama.o  magent  magent.c  magent.o  Makefile  [[email protected] magent]# cp magent /usr/bin/  

5.把产生的magent文件直接复制到从服务器。

[[email protected] bin]# yum install openssh-clients -y  [[email protected] bin]# scp magent [email protected]:/usr/bin/  

6.安装keepalived，修改默认配置文件。

[[email protected] bin]# yum install keepalived -y  [[email protected] bin]# vim /etc/keepalived/keepalived.conf  ! Configuration File for keepalived  vrrp_script magent {          script "/opt/shell/magent.sh"          interval 2  }    global_defs {     notification_email {       [email protected]       [email protected]       [email protected]     }     notification_email_from [email protected]     smtp_server 192.168.200.1     smtp_connect_timeout 30     router_id MAGENT_HA    //主服务器名称//  }    vrrp_instance VI_1 {      state MASTER      interface ens33     //网卡名称//      virtual_router_id 51      priority 100    //优先级//      advert_int 1      authentication {          auth_type PASS          auth_pass 1111      }      virtual_ipaddress {          192.168.126.188     //虚拟IP//      }  track_script {          magent     //函数//  }  }  

7.从服务器上安装keepalived，配置文件进行修改。

[[email protected] bin]# vim /etc/keepalived/keepalived.conf  ! Configuration File for keepalived  vi keepalived.conf  vrrp_script magent {          script "/opt/shell/magent.sh"          interval 2  }    global_defs {     notification_email {       [email protected]       [email protected]       [email protected]     }     notification_email_from [email protected]     smtp_server 192.168.200.1     smtp_connect_timeout 30     router_id MAGENT_HB      //从服务器的名称//  }    vrrp_instance VI_1 {      state BACKUP            //从服务器的热备状态要修改成BACKUP//      interface ens33  //网卡名称//      virtual_router_id 52    //不能与主服务器相同//      priority 90       //从调度器的优先级要小于主的//      advert_int 1      authentication {          auth_type PASS          auth_pass 1111      }      virtual_ipaddress {          192.168.126.188     //虚拟IP//      }  track_script {        //函数//          magent  }  }  

8.在主服务器上设置magent管理脚本

[[email protected] bin]# mkdir /opt/shell  [[email protected] bin]# vim /opt/shell/magent.sh    #!/bin/bash  K=`ps -ef | grep keepalived | grep -v grep | wc -l`  if [ $K -gt 0 ]; then          magent -u root -n 51200 -l 192.168.126.188 -p 12000 -s 192.168.126.138:11211 -b 192.168.126.166:11211  else  pkill -9 magent  fi    参数注解：  -n 51200 //定义用户最大连接数  -l 192.168.126.188 //指定虚拟IP  -p 12000  //指定端口号  -s //指定主缓存服务器  -b //指定从缓存服务器    [[email protected] shell]# chmod +x magent.sh   // 增加执行权限//  

9.在从服务器上操作

[[email protected] bin]# mkdir /opt/shell  [[email protected] bin]# cd /opt/shell/  [[email protected] shell]# vim magent.sh  [[email protected] shell]# vim magent.sh  脚本内容如下，与主服务器脚本有区别！  #!/bin/bash  K=`ip addr | grep 192.168.126.188 | grep -v grep | wc -l`  if [ $K -gt 0 ]; then          magent -u root -n 51200 -l 192.168.126.188 -p 12000 -s 192.168.126.138:11211 -b 192.168.126.166:11211  else  pkill -9 magent  fi  [[email protected] shell]# chmod +x magent.sh  

10.开始验证

1）启动主服务器

[[email protected] shell]# systemctl start keepalived.service  [[email protected] shell]# netstat -ntap | grep 12000  //确认magent运行//  tcp        0      0 192.168.126.188:12000   0.0.0.0:*               LISTEN      12422/magent  

2）启动从服务器

[[email protected] shell]# systemctl start keepalived.service  [[email protected] shell]# netstat -ntap | grep 12000  tcp        0      0 192.168.126.188:12000   0.0.0.0:*               LISTEN      11716/magent  

3）在主服务器上使用telnet进行简单验证复制功能

[[email protected] shell]# telnet 192.168.126.188 12000  //用漂移地址登陆服务//  Trying 192.168.126.188...  Connected to 192.168.126.188.  Escape character is '^]'.  add username 0 0 7      //添加一条键值数据//  1234567  STORED    在从服务器上查看  [[email protected] shell]# telnet 192.168.126.188 12000  Trying 192.168.126.188...  Connected to 192.168.126.188.  Escape character is '^]'.  get username    //查看键值数据  VALUE username 0 7  1234567         //内容存在，写入成功//  END  

11.在客户端用漂移地址登陆服务

[[email protected] ~]# yum install telnet -y  [[email protected] ~]# telnet 192.168.126.188 12000  Trying 192.168.126.188...  Connected to 192.168.126.188.  Escape character is '^]'.  add username 0 0 8    //添加一条键值数据//  12345678  STORED  

1）在主服务器和从服务器上查看是否写入成功。

主服务器  get username  VALUE username 0 8  12345678  END    从服务器  get username  VALUE username 0 8  12345678  END  

2）把主服务器停了业务不影响

[[email protected] shell]# systemctl stop keepalived.service  [[email protected] shell]# ip addr  inet 192.168.126.138/24 brd 192.168.126.255 scope global dynamic ens33  

3）在从服务器上查看

[[email protected] shell]# ip addr  inet 192.168.126.166/24 brd 192.168.126.255 scope global dynamic ens33         valid_lft 1146sec preferred_lft 1146sec      inet 192.168.126.188/32 scope global ens33  可以看到漂移地址已经转移到从服务器上了，说明从已接受工作。  

4）再把主服务器开启

[[email protected] shell]# systemctl start keepalived.service  [[email protected] shell]# ip addr  inet 192.168.126.138/24 brd 192.168.126.255 scope global dynamic ens33         valid_lft 1145sec preferred_lft 1145sec      inet 192.168.126.188/32 scope global ens33         valid_lft forever preferred_lft forever  漂移地址再次转移到主服务器上，接手地址，服务依然不受影响。  

实验成功

原文出处：51cto -> http://blog.51cto.com/13642258/2150442