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。

安装配置 HAProxy

#1准备好HAProxy安装包，传到/opt目录下
#2解压到/usr/local/src
tar -zxvf haproxy-1.5.18.tar.gz -C /usr/local/src
#3进入解压后的目录，查看内核版本，进行编译
cd /usr/local/src/haproxy-1.5.18
uname -r
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：3.10.0-514.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
		 stats hide-version
		 stats admin if TRUE

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
http://192.168.140.125:7777/admin
#在弹出框输入用户名：admin密码：123123
#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
mysql -umycat -p123456 -h 192.168.140.126 -P 48066

ha实现了mycat的负载均衡

配置 Keepalived

#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
#3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
#4进行编译，完成后进行安装
make && make install
#5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/
#6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
		 192.168.140.200
	 }
}
virtual_server 192.168.140.200 48066 {
	 delay_loop 6
	 lb_algo rr
	 lb_kind NAT
	 persistence_timeout 50
	 protocol TCP
	 real_server 192.168.140.125 48066 {
		 weight 1
		 TCP_CHECK {
		 	connect_timeout 3
		 	retry 3
	 		delay_before_retry 3
	 	}
	}
	real_server 192.168.140.126 48600 {
	 	weight 1
		TCP_CHECK {
			 connect_timeout 3
			 nb_get_retry 3
			 delay_before_retry 3
		 }
	 }
}

启动验证

#1启动Keepalived
service keepalived start
#2登录验证
mysql -umycat -p123456 -h 192.168.140.200 -P 48066