构建高可用集群Keepalived+Haproxy负载均衡

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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 – abs(weight)
主失败:
主 priority – abs(weight) < 从 priority 时会切换主从
主成功:
主 priority > 从 priority 主依然为主

主要贴配置：VIP：10.16.37.198,10.16.37.199

web 服务器 IP：10.16.37.94,10.16.37.101

二台 keepalived 的 IP：10.16.37.107,10.16.37.110

一台：

vi /etc/keepalived/keepalived.conf

! Configuration File for keepalived

global_defs {

  notification_email {

        linux@linuxidc

  }

  notification_email_from admin@lnmp.com

  smtp_connect_timeout 3

  smtp_server 127.0.0.1

  router_id Iptables

}

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 {

      10.16.37.198/22 dev eth0 label eth0:0

  }

  track_script {

      chk_haproxy

  }

  notify_master “/etc/keepalived/notify.sh master 10.16.37.198”

  notify_fault “/etc/keepalived/notify.sh fault 10.16.37.198”

}

vrrp_instance VI_2 {

  interface eth0

  state BACKUP

  priority 99

  virtual_router_id 126

  grap_master_delay 1

  authentication {

      auth_type pass

      auth_pass 7615c4b7f518cede

  }

  track_interface {

      eth0

  }

  virtual_ipaddress {

      10.16.37.199/22 dev eth0 label eth0:1

  }

  track_script {

      chk_haproxy

      chK_maintaince_down

  }

  notify_master “/etc/keepalived/notify.sh master 10.16.37.199”

  notify_backup “/etc/keepalived/notify.sh backup 10.16.37.199”

  notify_fault “/etc/keepalived/notify.sh fault 10.16.37.199”

}

另一台：vi /etc/keepalived/keepalived.conf

! Configuration File for keepalived

global_defs {

  notification_email {

        linux@linuxidc

  }

  notification_email_from admin@lnmp.com

  smtp_connect_timeout 3

  smtp_server 127.0.0.1

  router_id Iptables

}

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 {

      10.16.37.198/22 dev eth0 label eth0:1

  }

  track_script {

      chk_haproxy

  }

  notify_master “/etc/keepalived/notify.sh master 10.16.37.198”

  notify_fault “/etc/keepalived/notify.sh fault 10.16.37.198”

}

vrrp_instance VI_2 {

  interface eth0

  state MASTER

  priority 100

  virtual_router_id 126

  grap_master_delay 1

  authentication {

      auth_type pass

      auth_pass 7615c4b7f518cede

  }

  track_interface {

      eth0

  }

  virtual_ipaddress {

      10.16.37.199/22 dev eth0 label eth0:0

  }

  track_script {

      chk_haproxy

      chK_maintaince_down

  }

  notify_master “/etc/keepalived/notify.sh master 10.16.37.199”

  notify_backup “/etc/keepalived/notify.sh backup 10.16.37.199”

  notify_fault “/etc/keepalived/notify.sh fault 10.16.37.199”

}

脚本配置：

vi /etc/keepalived/notify.sh

#!/bin/bash

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

        exit 0

    ;;

    fault)

        notify fault $2

        exit 0

    ;;

    *)

        echo ‘Usage: ‘basename $0′ {master|backup|fault}’

        exit 1

    ;;

Esac

Haproxy 配置：

vi /etc/haproxy/haproxy.cfg

#———————————————————————

# 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

#———————————————————————

# main frontend which proxys to the backends

#———————————————————————

#frontend  main *:5000

#    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

#    server      static 127.0.0.1:4331 check

#———————————————————————

# round robin balancing between the various backends

#———————————————————————

#backend app

#    balance    roundrobin

#    server  app1 127.0.0.1:5001 check

#    server  app2 127.0.0.1:5002 check

#    server  app3 127.0.0.1:5003 check

#    server  app4 127.0.0.1:5004 check

listen stats

    mode http

    bind 0.0.0.0:1080

    stats enable

    stats refresh 30s

    maxconn 200

    stats hide-version

    stats uri    /haproxy-stats

    stats realm  Haproxy\ Statistics

    stats auth    admin:admin

    stats admin if TRUE

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

    default_backend dynamic_servers

backend static_servers

    balance roundrobin

    server imgsrv1 10.16.37.101:80 check maxconn 6000

    server imgsrv2 10.16.37.94:80 check maxconn 6000

backend dynamic_servers

    balance source

    server websrv1 10.16.37.94:80 check maxconn 1000

server websrv2 10.16.37.101:80 check maxconn 1000

因为端口使用的是 1080 需要 Iptables 开启：

/sbin/iptables –I INPUT –p tcp –dport 1080 –j ACCEPT

/etc/rc.d/init.d/iptables save

Service iptables restart

Vi /etc/selinux/config

关闭 selinux 然后呢重启！！

二个 server web 采用 nginx+ 双主 mysql 数据库，保证了 web 服务器的高可用性能，一台服务器宕机，另外一台立马连接！！

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