Magent搭建Memcached高可用群集

Magent缓存代理介绍

因为 Memcached 服务器与服务器之间没有任何通讯，所以当任何服务器节点出现故障时，会出现单点故障。通过Magent缓存代理，防止单点现象。通过客户端连接到缓存代理服务器，缓存代理服务器可以连接多台Memcached机器并同时将每台Memcached机器进行数据同步。如果其中一台缓存服务器down机，系统依然可以继续工作，如果其中一台Memcached机器down掉，数据不会丢失并且可以保证数据的完整性。

原理演示图：

实验环境介绍：

三台服务器：

master/slave/client

实验步骤

在master和slave上同时安装libevent、memcached

master&&slave:

systemctl stop firewalld.service
setenforce 0
tar zxvf memcached-1.5.6.tar.gz -C /opt
tar zxvf libevent-2.1.8-stable.tar.gz -C /opt
yum install gcc gcc-c++ -y
cd /opt/libevent-2.1.8-stable/
./configure --prefix=/usr/local
make && make install
cp /usr/local/lib/libevent-2.1.so.6 /usr/lib64/
 
cd /opt/memcached-1.5.6/
./configure --with-libevent=/usr/local
make && make install

在master上安装配置magent

master:

mkdir /opt/magent
tar zxvf magent-0.5.tar.gz -C /opt
vim /opt/magent/ketama.h
     #ifndef SSIZE_MAX
     #define SSIZE_MAX 32767
     #endif
vim /opt/magent/Makefile
     LIBS = -levent -lm                 此处为英文单词‘l’,不是1
make

将magent命令复制到slave服务器上

注：标记地方为需要更改的位置

yum install openssl-clients -y

cp magent /usr/bin

scp magent root@192.168.218.157:/usr/bin

yum install keepalived -y

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 MAGENT_HA

}

vrrp_script magent {

script "/opt/shell/magent.sh"             脚本位置

interval 2                                                  检测脚本为2秒

}

vrrp_instance VI_1 {

state MASTER

interface ens33

virtual_router_id 51

priority 100

advert_int 1

authentication {

auth_type PASS

auth_pass 1111

}

track_script {                   调用vrrp_script magent

magent

}

virtual_ipaddress {

192.168.218.16

}

}

从服务器上安装配置keepalived

slave:

yum install openssl-clients -y
yum install keepalived -y
cd /etc/keepalived/
mv keepalived.conf keepalived.conf.bk

master:

cd /etc/keepalived/
scp keepalived.conf root@192.168.218.157:/etc/keepalived/keepalived.conf

slave:

vim /etc/keepalived/keepalived.conf
            global_defs {
            router_id MAGENT_HB
           vrrp_instance VI_1 {
            state BACKUP
            virtual_router_id 52
             priority 90

master:

      #!/bin/bash
      k=`ps -ef | grep keepalived | grep -v grep | wc -l`
       if [ $k -gt 0 ];then
           magent -u root -n 51200 -l 192.168.218.16 -p 12000 -s 192.168.218.130:11211 -b 192.168.218.157:11211
         else
            pkill -9 magent
       fi

slave:

       #!/bin/bash
       K=`ip addr | grep 192.168.218.16 | grep -v grep | wc -l`
       if [ $K -gt 0 ];then
          magent -u root -n 51200 -l 192.168.218.16 -p 12000 -s 192.168.218.130:11211 -b 192.168.218.157:11211
       else
           pkill -9 magent
       fi

#magent -u指定用户、-n指定连接数量、-l指定漂移地址、-p指定端口、-s指定主服务器地址、-b指定从服务器地址

chmod +x /opt/shell/magent.sh
systemctl start keepalived.servic
netstat -ntap | grep 12000                   #此时检查应有12000端口号

master:

memcached -m 512k -u root -d -l 192.168.218.130 -p 11211
netstat -ntap | grep 11211

slave:

memcached -m 512k -u root -d -l 192.168.218.157 -p 11211
netstat -ntap | grep 11211

测试：

master:

yum install telnet -y
telnet 192.168.218.130 11211

slave:

yum install telnet -y
telnet 192.168.218.157 11211

client：

yum install telnet -y
telnet 192.168.218.16 12000
         Trying 192.168.218.16...
         Connected to 192.168.218.16.
         Escape character is '^]'.
         add username 0 0 7                #写入一段数据
         1231231
          STORED

slave:

telnet 192.168.218.157 11211
          Trying 192.168.218.157...
          Connected to 192.168.218.157.
         Escape character is '^]'.
         get username
         VALUE username 0 7
        1231231                                  #在主服务器和从服务器上可以看到同步过来的数据
        END