在实际项目中，Mycat服务也需要考虑高可用性，如果Mycat所在的服务器出现宕机，或者Mycat服务故障，需要有备机提供服务，需要考虑Mycat集群。
高可用方案：
我们可以使用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，而HAProxy自身的高可用则可以通过Keepalived来实现。
Mycat及主从可参考MySQL 中间件Mycat部署
| 主机名 | 运行服务 | IP |
|---|---|---|
| haproxy | HAProxy+Keepalived | 192.168.171.132 |
| haproxy2 | HAProxy+Keepalived | 192.168.171.136 |
| mycat1 | Mycat | 192.168.171.134 |
| mycat2 | Mycat | 192.168.171.140 |
| master1 | MySQL主1 | 192.168.171.135 |
| slave | MySQL从 | 192.168.171.145 |
| master2 | MySQL主2 | 192.168.171.131 |
一、安装配置HAProxy
[root@haproxy ~]# wget https://src.fedoraproject.org/repo/pkgs/haproxy/haproxy-1.8.23.tar.gz/sha512/bfd65179345285f6f4581a7dce42e638b89e12717d4cb9218afa085759161e04b6c78307d04265a6c97cd484b67949781639da5236edb89137585c625130be4f/haproxy-1.8.23.tar.gz
[root@haproxy ~]# tar zxf haproxy-1.8.23.tar.gz
[root@haproxy ~]# cd haproxy-1.8.23/
#查看内核版本
[root@haproxy haproxy-1.8.23]# uname -r
3.10.0-514.el7.x86_64
#查看位shu
[root@haproxy ~]# uname -m
x86_64
#进行编译
[root@haproxy haproxy-1.8.23]# make TARGET=linux310 PREFIX=/usr/local/haproxy ARCH=x86_64
#编译完成后安装
[root@haproxy haproxy-1.8.23]# make install PREFIX=/usr/local/haproxy
[root@haproxy ~]# vim /usr/local/haproxy/haproxy.conf
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/local/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 # 轮询方式访问mycat
server mycat_1 192.168.171.134:8066 check inter 10s
server mycat_2 192.168.171.140:8066 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
stats hide-version
stats admin if TRUE
[root@haproxy ~]# /usr/local/haproxy/sbin/haproxy -f /usr/local/haproxy/haproxy.conf # 启动
[root@haproxy ~]# ss -anput | grep haproxy # 查看是否启动
udp UNCONN 0 0 *:33498 *:* users:(("haproxy",pid=4535,fd=4))
tcp LISTEN 0 10 *:7777 *:* users:(("haproxy",pid=4535,fd=5))
tcp LISTEN 0 128 *:48066 *:* users:(("haproxy",pid=4535,fd=3))浏览器访问http://192.168.171.132/admin:7777
在弹出框输入账户密码
验证负载均衡，通过haproxy访问Mycat
[root@haproxy ~]# mysql -umycat -p123456 -h192.168.171.132 -P48066再次安装配置一个haproxy服务器（配置方法同上）
#将之前的配置文件传到新安装的haproxy
[root@haproxy ~]# scp /usr/local/haproxy/haproxy.conf [email protected]:/usr/local/haproxy/
#启动haproxy2
[root@hahaproxy2 haproxy-1.8.23]# /usr/local/haproxy/sbin/haproxy -f /usr/local/haproxy/haproxy.conf二、配置Keepalived
#在两个haproxy主机上都安装上Keepalived
#安装依赖包
[root@haproxy ~]# yum -y install openssl-devel popt-devel kernel-devel
[root@haproxy ~]# tar zxf keepalived-2.0.20.tar.gz
[root@haproxy ~]# cd keepalived-2.0.20/
[root@haproxy keepalived-2.0.20]# ./configure --prefix=/ && make && make install
[root@haproxy ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
router_id LVS_DEVEL
}
vrrp_instance VI_1 {
state MASTER
interface ens33
virtual_router_id 51
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.171.250 # VIP地址
}
}
virtual_server 192.168.171.250 48066 {
delay_loop 6
lb_algo rr
lb_kind NAT
persistence_timeout 50
protocol TCP
real_server 192.168.171.132 48066 {
weight 1
TCP_CHECK {
connect_timeout 3
retry 3
delay_before_retry 3
}
}
real_server 192.168.171.136 48066 {
weight 1
TCP_CHECK {
connect_timeout 3
retry 3
delay_before_retry 3
}
}
}
[root@haproxy ~]# systemctl start keepalived # 启动服务
#将配置文件复制到haproxy2上
[root@localhost ~]# scp /etc/keepalived/keepalived.conf [email protected]:/etc/keepalived/
#修改haproxy上的Keepalived配置文件
! Configuration File for keepalived
global_defs {
router_id LVS_2 # 修改id
}
vrrp_instance VI_1 {
state BACKUP # 修改状态
interface ens33
virtual_router_id 51
priority 50 # 优先级修改
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.171.250
}
}
[root@haproxy2 ~]# systemctl start keepalived测试高可用，连接VIP地址进行管理mycat
[root@haproxy ~]# mysql -umycat -p123456 -h192.168.171.250 -P48066
mysql> show databases;
+----------+
| DATABASE |
+----------+
| TESTDB |
+----------+
1 row in set (0.00 sec)Mycat安全设置
1、权限配置
1）user标签权限控制
目前Mycat对于中间件的连接控制并没有做太复杂的控制，目前只做了中间件逻辑库级别的读写权限控制。
#修改server.xml配置文件user部分
<user name="mycat" defaultAccount="true">
<property name="password">123456</property>
<property name="schemas">TESTDB</property>
<property name="defaultSchema">TESTDB</property>
</user>
user name="user">
<property name="password">user</property>
<property name="schemas">TESTDB</property>
<property name="readOnly">true</property>
<property name="defaultSchema">TESTDB</property>
</user>2）privileges标签权限控制
在user标签下的privilege标签可以对逻辑库（schema）、表（table）进行精细化的DML权限控制。privileges标签下的check属性，如为true开启权限检查，为false不开启，默认为false。
由于Mycat一个用户的schemas属性可配置多个逻辑库（schema），所以privileges的下级节点schema节点同样可配置多个，对多库多表进行细粒度的DML权限控制
#修改server.xml的privileges部分
<!-- 表级 DML 权限设置 -->
<privileges check="false">
<schema name="TESTDB" dml="0110" >
<table name="tb01" dml="0000"></table>
<table name="tb02" dml="1111"></table>
</schema>
</privileges> 
SQL拦截
firewall标签用来定义防火墙；firewall下whitehost标签用来定义IP白名单，blacklist用来定义SQL黑名单。
1、设置白名单
#srserver.xml配置文件
<firewall>
<whitehost>
<host host="192.168.171.250" user="root"/>
</whitehost>
</firewall>2、设置黑名单
<firewall>
<whitehost>
<host host="192.168.171.250" user="root"/>
</whitehost>
<blacklist check="true">
<property name="deleteAllow">false</property>
</blacklist>
</firewall>可以设置的黑名单SQL拦截列表