7、基于 HA 机制的 Mycat 高可用--mycat
在实际项目中，Mycat 服务也需要考虑高可用性，如果 Mycat 所在服务器出现宕机，或 Mycat 服
务故障，需要有备机提供服务，需要考虑 Mycat 集群。
1、 高可用方案
使用 HAProxy + Keepalived 配合两台 Mycat 搭起 Mycat 集群，实现高可用性。
HAProxy实现了 MyCat 多节点的集群高可用和负载均衡
HAProxy 自身的高可用则可以通过 Keepalived 来实现。
| 角色 | ip |
| mycat01 | 192.168.199.217 |
| mycat02 | 192.168.199.120 |
| HA(主) | 192.168.199.174 |
| keepalive（主机） | 192.168.199.174 |
| HA(主) | 192.168.199.199 |
| keepalive（主机 | 192.168.199.199 |
先配置好mycat并且启动mycat
2 安装配置 HAProxy
1、 安装 HAProxy
2解压到/usr/local/src
3进入解压后的目录，查看内核版本，进行编译
[root@mycat05 software]# cd /usr/local/src/haproxy-1.5.18/
[root@mycat05 haproxy-1.5.18]# uname -r
3.10.0-957.el7.x86_64
[root@mycat05 haproxy-1.5.18]# make TARGET=linux310 PREFIX=/usr/local/haproxy ARCH=x86_64
# ARGET=linux310，内核版本，使用uname -r查看内核，如：3.10.0-957.el7，此时该参数就为linux310；
#ARCH=x86_64，系统位数；
#PREFIX=/usr/local/haprpxy #/usr/local/haprpxy，为haprpxy安装路径。
4编译完成后，进行安装
make install PREFIX=/usr/local/haproxy
5安装完成后，创建目录、创建HAProxy配置文件
mkdir -p /usr/data/haproxy/
vim /usr/local/haproxy/haproxy.conf
6向配置文件中插入以下配置信息,并保存
global log 127.0.0.1 local0 #log 127.0.0.1 local1 notice #log loghost local0 info maxconn 4096 chroot /usr/local/haproxy pidfile /usr/data/haproxy/haproxy.pid uid 99 gid 99 daemon #debug #quiet defaults log global mode tcp option abortonclose option redispatch retries 3 maxconn 2000 timeout connect 5000 timeout client 50000 timeout server 50000 listen proxy_status bind :48066 mode tcp balance roundrobin server mycat_1 192.168.140.128:8066 check inter 10s server mycat_2 192.168.140.127:8066 check inter 10s frontend admin_stats bind :7777 mode http stats enable option httplog maxconn 10 stats refresh 30s stats uri /admin stats auth admin:123123 //登陆账户and密码 stats hide-version stats admin if TRUE
2、 启动验证
1启动HAProxy
/usr/local/haproxy/sbin/haproxy -f /usr/local/haproxy/haproxy.conf
2查看HAProxy进程
ps -ef|grep haproxy
3打开浏览器访问
如果Mycat主备机均已启动，则可以看到如下图
4验证负载均衡，通过HAProxy访问Mycat
在HAProxy主机上执行（192.168.199.174HA的主机地址）
[root@mycat05 haproxy-1.5.18]# mysql -umycat -p123456 -h 192.168.199.174 -P 48066
3 配置 Keepalived
下载地址：https://www.keepalived.org/software/
1准备好Keepalived安装包，传到/opt目录下
2解压到/usr/local/src
tar -zxvf keepalived-1.4.2.tar.gz -C /usr/local/src
3安装依赖插件
yum install -y gcc openssl-devel popt-devel
4进入解压后的目录，进行配置，进行编译
cd /usr/local/src/keepalived-1.4.2
./configure --prefix=/usr/local/keepalived
5进行编译，完成后进行安装
make && make install
6运行前配置
cp /usr/local/src/keepalived-1.4.2/keepalived/etc/init.d/keepalived /etc/init.d/
mkdir /etc/keepalived
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
cp /usr/local/src/keepalived-1.4.2/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
7修改配置文件
vim /etc/keepalived/keepalived.conf
#修改内容如下 ! Configuration File for keepalived global_defs { notification_email { xlcocoon@foxmail.com } notification_email_from keepalived@showjoy.com smtp_server 127.0.0.1 smtp_connect_timeout 30 router_id LVS_DEVEL vrrp_skip_check_adv_addr vrrp_garp_interval 0 vrrp_gna_interval 0 } vrrp_instance VI_1 { #主机配MASTER，备机配BACKUP state MASTER #所在机器网卡 interface ens33 virtual_router_id 51 #数值越大优先级越高 priority 100 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { #虚拟IP 192.168.199.111 } } virtual_server 192.168.199.111 48066 { delay_loop 6 lb_algo rr lb_kind NAT persistence_timeout 50 protocol TCP real_server 192.168.199.174 48066 { # HA的地址（主机） weight 1r TCP_CHECK { connect_timeout 3 retry 3 delay_before_retry 3 } } real_server 192.168.199.199 48600 {#HA地址（备机r） weight 1 TCP_CHECK { connect_timeout 3 nb_get_retry 3 delay_before_retry 3 } } }
8、启动Keepalived
同时启动备机上的HA
service keepalived start
9、登录验证
mysql -umycat -p123456 -h 192.168.199.111 -P 48066
192.168.199.111 ：虚拟ip
此时是：
HA隐藏mycat的ip
KeepAlive隐藏HA的ip
4 测试高可用
1关闭mycat
2通过虚拟ip查询数据
mysql -umycat -p123456 -h 192.168.199.111 -P 48066
mysql> select * from orders; ERROR 2013 (HY000): Lost connection to MySQL server during query
mysql> select * from orders; ERROR 2006 (HY000): MySQL server has gone away No connection. Trying to reconnect... Connection id: 2 Current database: TESTDB +--------+------------+-------------+-----------+ | id | order_type | customer_id | amount | +--------+------------+-------------+-----------+ | 1 | 101 | 100 | 100100.00 | | 2 | 101 | 100 | 100300.00 | | 6 | 102 | 100 | 100020.00 | | 3 | 101 | 101 | 120000.00 | | 4 | 101 | 101 | 103000.00 | | 5 | 102 | 101 | 100400.00 | | 400100 | 102 | 101 | 1000.00 | | 400101 | 102 | 101 | 1000.00 | +--------+------------+-------------+-----------+ 8 rows in set (1.46 sec)
