mycat+haproxy服务与高可用（

1.服务器

192.168.9.34 haproxy --->haproxy
192.168.9.37 haproxy-keeplived --->haproxy
192.168.9.35 service1 --->nginx
192.168.9.36 service2 --->nginx+tomcat

2.进行web进行haproxy负载均衡

#---------------------------------------------------------------------
# Example configuration for a possible web application.  See the
# full configuration options online.
#
#   http://haproxy.1wt.eu/download/1.4/doc/configuration.txt
#
#---------------------------------------------------------------------

#---------------------------------------------------------------------
# Global settings
#---------------------------------------------------------------------
global
    # to have these messages end up in /var/log/haproxy.log you will
    # need to:
    #
    # 1) configure syslog to accept network log events.  This is done
    #    by adding the '-r' option to the SYSLOGD_OPTIONS in
    #    /etc/sysconfig/syslog
    #
    # 2) configure local2 events to go to the /var/log/haproxy.log
    #   file. A line like the following can be added to
    #   /etc/sysconfig/syslog
    #
    #    local2.*                       /var/log/haproxy.log
    #
    log         127.0.0.1 local2

    chroot      /var/lib/haproxy
    pidfile     /var/run/haproxy.pid
    maxconn     4000
    user        haproxy
    group       haproxy
    daemon

    # turn on stats unix socket
    stats socket /var/lib/haproxy/stats

#---------------------------------------------------------------------
# common defaults that all the 'listen' and 'backend' sections will
# use if not designated in their block
#---------------------------------------------------------------------
defaults
    mode                    http
    log                     global
    option                  httplog
    option                  dontlognull
    option http-server-close
    option forwardfor       except 127.0.0.0/8
    option                  redispatch
    retries                 3
    timeout http-request    10s
    timeout queue           1m
    timeout connect         10s
    timeout client          1m
    timeout server          1m
    timeout http-keep-alive 10s
    timeout check           10s
    maxconn                 3000

#---------------------------------------------------------------------
# listen page
#---------------------------------------------------------------------
listen stats
    mode http
    bind 0.0.0.0:1080
    stats enable
    stats hide-version
    stats uri     /listen-page
    stats realm   welcome login\ listen-page
    stats auth    admin:000000
    stats admin if TRUE

#---------------------------------------------------------------------
# main frontend which proxys to the backends
#---------------------------------------------------------------------
frontend  main *:80                      #haproxy的监听端口
    acl url_static       path_beg       -i /static /images /javascript /stylesheets
    acl url_static       path_end       -i .jpg .gif .png .css .js

    use_backend static          if url_static
    default_backend             app

#---------------------------------------------------------------------
# static backend for serving up images, stylesheets and such
#---------------------------------------------------------------------
backend static
    balance     roundrobin
    option httpchk GET /index.html
    server      static1 192.168.9.35:80 check port 80 inter 5s rise 2 fall 3

#---------------------------------------------------------------------
# round robin balancing between the various backends
#---------------------------------------------------------------------
backend app
    balance     roundrobin
    server      app1 192.168.9.35 check port 80 inter 5s rise 2 fall 3
    server      app2 192.168.9.36 check port 80 inter 5s rise 2 fall 3

3.其他应用的后端健康检查与负载均衡
3.1摘录

3.2摘录

3.3摘录


4.haproxy的keepalived高可用
4.1安装keeplived

[root@haproxy ~]# yum -y install keepalived

4.2修改keeplived 的配置文件，配置自己需要的配置
4.2.1修改主从的配置文件

[root@haproxy ~]# vim /etc/keepalived/keepalived.conf 

! Configuration File for keepalived
global_defs {
   router_id master                              #此处唯一
}
vrrp_script checkhaproxy {
        script "/usr/local/bin/chk_haproxy.bash"
        weight -20
        interval 3
}
vrrp_instance VI_1 {
    state MASTER                             #此处为MASTER或BACKUP
    interface ens33
    virtual_router_id 51                      #此处为虚拟组，要相同表示一个组
    priority 100                                   #此处为优先级，MASTR要大
    advert_int 1                                  #广播时间间隔
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    track_script {
            checkhaproxy
    }
    virtual_ipaddress {
        192.168.9.202/24
    }
}

[root@haproxy-keeplived ~]# vim /etc/keepalived/keepalived.conf 

! Configuration File for keepalived
global_defs {
   router_id slave
}
vrrp_script checkhaproxy {
        script "/usr/local/bin/chk_haproxy.bash"
        weight -20
        interval 3
}
vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    virtual_router_id 51
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    track_script {
        checkhaproxy
    }
    virtual_ipaddress {
        192.168.9.202/24
    }
}

track_script 中调用 checkhaproxy

checkhaproxy 的意思是：

每3秒种执行一次 /usr/local/keepalived/script/chk_haproxy.bash 脚本 如果反馈结果是 0，就保持原优先级 priority ，如果是 1 ，就将优先级降低 20，也就是检查到 haproxy 状态异常后，就降级，以便让另一台服务器的keepalived进程可以抢到IP

为了避免网络的不稳定还可以加入 fall N (代表连续N次检查失败才算异常) 和 rise N (代表连续N次检查成功就算正常)

---

Tip: keepalived 相互之间的通讯要使用到组播，如果没打开，会出现几个实例同时抢占着IP的情况，打开方式是在iptables中加入 -A INPUT -d 224.0.0.18 -j ACCEPT，然后重载iptables配置（这个ip可以更改）

---

如果同一个局域网内存在多组Keepalived服务器对，就会造成IP多播地址冲突问题，导致接管错乱，不同组的Keepalived都会使用默认的224.0.0.18作为多播地址。此时的解决办法是，在同组的Keepalived服务器所有的配置文件里指定独一无二的多播地址，配置如下：

global_defs {
router_id LVS_19
vrrp_mcast_group4 224.0.0.19 #这个就是指定多播地址的配置
}

       ＃组播组用于IPv4 VRRP通告
       ＃（默认值：224.0.0.18）
       vrrp_mcast_group4 224.0.0.18

       #Multicast Group用于IPv6 VRRP通告
       ＃（默认值：ff02 :: 12）
       vrrp_mcast_group6 ff02 :: 12

4.2.2检查状态脚本
[root@haproxy ~]# vim /usr/local/bin/chk_haproxy.bash

#!/bin/bash
count=`ps aux | grep -v grep | grep haproxy.cfg | wc -l`
if [ $count -gt 0 ]; then
    exit 0
else
    pkill keepalived
    exit 1
fi

增加执行权限
[root@haproxy ~]# chmod +x /usr/local/bin/chk_haproxy.bash

5.裂脑检查脚本
[root@lb02 scripts]# cat check_split_brain.sh

#!/bin/bash
lb01_vip=192.168.0.240
lb01_ip=192.168.0.221
while true
do
ping -c 2 -W 3 $lb01_ip &>/dev/null
if [ $? -eq 0 -a `ip a | grep "$lb01_vip" | wc -l` -eq 1 ];then
echo "ha is split brain.warning."
else
echo "ha is OK"
fi
sleep 5
done

可以将此脚本整合到Nagios或Zabbix监控服务里，进行监控报警。

6: 配置日志

keepalived 默认将日志输出到系统日志/var/log/messages中，因为系统日志很多，查询问题时相对麻烦。
我们可以将 keepalived 的日志单独拿出来，这需要修改日志输出路径。

修改 Keepalived 配置

[root@haproxy ~]# vim /etc/sysconfig/keepalived
更改如下：

即把 KEEPALIVED_OPTIONS=”-D” 修改为KEEPALIVED_OPTIONS=”-D -d -S 0”，其中 -S 指定 syslog 的 facility

修改日志rsyslog.con配置
[root@haproxy ~]# vim /etc/rsyslog.conf

mofa模仿上面添加
local0.* /var/log/keepalived.log

---

重启日志记录服务
[root@haproxy ~]# systemctl restart rsyslog
重启 keepalived
[root@haproxy ~]# systemctl restart keepalived

此时，可以从 /var/log/keepalived.log 查看日志了。