如何快速构建高可用集群(Keepalived+Haproxy+Nginx)

组件及实现的功能

• Keepalived：实现对Haproxy服务的高可用，并采用双主模型配置;

• Haproxy：实现对Nginx的负载均衡和读写分离;

• Nginx：实现对HTTP请求的高速处理;

架构设计图

重点概念

vrrp_script中节点权重改变算法

vrrp_script 里的script返回值为0时认为检测成功，其它值都会当成检测失败；

weight 为正时，脚本检测成功时此weight会加到priority上，检测失败时不加；

主失败:

主 priority < 从 priority + weight 时会切换。

主成功：

主 priority + weight > 从 priority + weight 时，主依然为主

weight 为负时，脚本检测成功时此weight不影响priority，检测失败时priority �C abs(weight)

主失败:

主 priority �C abs(weight) < 从priority 时会切换主从

主成功:

主 priority > 从priority 主依然为主

具体解释详见博文“Keepalived双主模型中vrrp_script中权重改变故障排查”

部署配置

Keepalived部署

配置

yum -y install keepalived # 两节点都需部署
# 172.16.25.109
# vi /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
   notification_email {
         root@localhost
   }
   notification_email_from [email protected]
   smtp_connect_timeout 3
   smtp_server 127.0.0.1
   router_id LVS_DEVEL
}
vrrp_script chk_maintaince_down {
   script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"
   interval 1
   weight 2
}
vrrp_script chk_haproxy {
    script "killall -0 haproxy"
    interval 1
    weight 2
}
vrrp_instance VI_1 {
    interface eth0
    state MASTER
    priority 100
    virtual_router_id 125
    garp_master_delay 1
    authentication {
        auth_type PASS
        auth_pass 1e3459f77aba4ded
    }
    track_interface {
       eth0
    }
    virtual_ipaddress {
        172.16.25.10/16 dev eth0 label eth0:0
    }
    track_script {
        chk_haproxy
    }
    notify_master "/etc/keepalived/notify.sh master 172.16.25.10"
    notify_backup "/etc/keepalived/notify.sh backup 172.16.25.10"
    notify_fault "/etc/keepalived/notify.sh fault 172.16.25.10"
}
vrrp_instance VI_2 {
    interface eth0
    state BACKUP
    priority 99
    virtual_router_id 126
    garp_master_delay 1
    authentication {
        auth_type PASS
        auth_pass 7615c4b7f518cede
    }
    track_interface {
       eth0
    }
    virtual_ipaddress {
        172.16.25.11/16 dev eth0 label eth0:1
    }
    track_script {
        chk_haproxy
chk_maintaince_down
    }
    notify_master "/etc/keepalived/notify.sh master 172.16.25.11"
    notify_backup "/etc/keepalived/notify.sh backup 172.16.25.11"
    notify_fault "/etc/keepalived/notify.sh fault 172.16.25.11"
}
# 172.16.25.110
# vi /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
   notification_email {
         root@localhost
   }
   notification_email_from [email protected]
   smtp_connect_timeout 3
   smtp_server 127.0.0.1
   router_id LVS_DEVEL
}
vrrp_script chk_maintaince_down {
   script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"
   interval 1
   weight 2
}
vrrp_script chk_haproxy {
    script "killall -0 haproxy"
    interval 1
    weight 2
}
vrrp_instance VI_1 {
    interface eth0
    state BACKUP
    priority 99
    virtual_router_id 125
    garp_master_delay 1
    authentication {
        auth_type PASS
        auth_pass 1e3459f77aba4ded
    }
    track_interface {
       eth0
    }
    virtual_ipaddress {
        172.16.25.10/16 dev eth0 label eth0:0
    }
    track_script {
        chk_haproxy
chk_maintaince_down
    }
    notify_master "/etc/keepalived/notify.sh master 172.16.25.10"
    notify_backup "/etc/keepalived/notify.sh backup 172.16.25.10"
    notify_fault "/etc/keepalived/notify.sh fault 172.16.25.10"
}
vrrp_instance VI_2 {
    interface eth0
    state MASTER
    priority 100
    virtual_router_id 126
    garp_master_delay 1
    authentication {
        auth_type PASS
        auth_pass 7615c4b7f518cede
    }
    track_interface {
       eth0
    }
    virtual_ipaddress {
        172.16.25.11/16 dev eth0 label eth0:1
    }
    track_script {
        chk_haproxy
    }
    notify_master "/etc/keepalived/notify.sh master 172.16.25.11"
    notify_backup "/etc/keepalived/notify.sh backup 172.16.25.11"
    notify_fault "/etc/keepalived/notify.sh fault 172.16.25.11"
}
# vi /etc/keepalived/notify.sh
#!/bin/bash
# Author: Jason.Yu <[email protected]>
# description: An example of notify script
#
contact='root@localhost'
notify() {
    mailsubject="`hostname` to be $1: $2 floating"
    mailbody="`date '+%F %H:%M:%S'`: vrrp transition, `hostname` changed to be $1"
    echo $mailbody | mail -s "$mailsubject" $contact
}
case "$1" in
    master)
        notify master $2
        /etc/rc.d/init.d/haproxy restart
        exit 0
    ;;
    backup)
        notify backup $2 # 在节点切换成backup状态时，无需刻意停止haproxy服务，防止chk_maintaince和chk_haproxy多次对haproxy服务操作；
        exit 0
    ;;
    fault)
        notify fault $2 # 同上
        exit 0
    ;;
    *)
        echo 'Usage: `basename $0` {master|backup|fault}'
        exit 1
    ;;
esac

启动服务

service keepalived start # 在两个节点上都需要启动

keepalived双主模型启动

Haproxy部署

安装配置

yum -y install haproxy # 两节点都需部署
vi /etc/haproxy/haproxy.cfg # 两节点配置一致
global
    log         127.0.0.1 local2
    chroot      /var/lib/haproxy
    pidfile     /var/run/haproxy.pid
    maxconn     4000
    user         haproxy
    group       haproxy
    daemon # 以后台程序运行；
defaults
    mode                   http # 选择HTTP模式，即可进行7层过滤；
    log                     global
    option                  httplog # 可以得到更加丰富的日志输出；
    option                  dontlognull
    option http-server-close # server端可关闭HTTP连接的功能；
    option forwardfor except 127.0.0.0/8 # 传递client端的IP地址给server端，并写入“X-Forward_for”首部中；
    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                 30000
listen stats
    mode http
    bind 0.0.0.0:1080 # 统计页面绑定1080端口；
    stats enable # 开启统计页面功能；
    stats hide-version # 隐藏Haproxy版本号；
    stats uri     /haproxyadmin?stats # 自定义统计页面的访问uri；
    stats realm   Haproxy\ Statistics # 统计页面密码验证时的提示信息；
    stats auth    admin:admin # 为统计页面开启登录验证功能；
    stats admin if TRUE # 若登录用户验证通过，则赋予管理功能；
frontend http-in
    bind *:80
    mode http
    log global
    option httpclose
    option logasap
    option dontlognull
    capture request  header Host len 20
    capture request  header Referer len 60
    acl url_static       path_beg       -i /static /images /javascript /stylesheets
    acl url_static       path_end       -i .jpg .jpeg .gif .png .css .js .html
    use_backend static_servers if url_static # 符合ACL规则的，请求转入后端静态服务器
    default_backend dynamic_servers # 默认请求转入后端动态服务器
backend static_servers
    balance roundrobin
    server imgsrv1 192.168.0.25:80 check maxconn 6000 # 静态服务器，可配置多台，还可设置权重weight；
backend dynamic_servers
    balance source # 对于动态请求利用source调度算法，可一定程度上实现session保持；但最好利用cookie绑定的方式实现session保持
    server websrv1 192.168.0.35:80 check maxconn 1000 # 动态服务器，可配置多台，还可设置权重weight；

启动服务

service haproxy start # 两节点都需要启动

Nginx部署

见博客“如何测试Nginx的高性能”

访问验证

Haproxy统计页面测试

动静分离测试

高可用测试