利用keepalived实现nginx七层负载均衡器双主模型高可用集群

nginx通过ngx_http_upstream_module可以实现七层http服务的负载均衡，同时还自带RS的健康监测功能，但是也有弊端，nginx负载均衡器如果发生故障则整个集群失效，此文通过keepalived构建nginx负载均衡器的高可用集群。

一、实验环境：

实验需要4台服务器：

nginx负载均衡器1：192.168.11.100

nginx负载均衡器2：192.168.11.101

nginx静态网页服务器1：192.168.11.201

nginx静态网页服务器2：192.168.11.202

拓扑如下：

二、实验步骤：

负载均衡器配置：

1. 安装nginx和keepalived

   yum install -y nginx keepalived

2. 修改keepalived配置文件：

   ! Configuration File for keepalived  global_defs {    notification_email {         root@localhost    }    notification_email_from keepalived@localhost    smtp_server 127.0.0.1    smtp_connect_timeout 30    router_id node1    vrrp_mcast_group1 224.0.115.17 #组播ip地址# }  #服务检测脚本1：当/etc/keepalived目录下存在down文件，则权重-5# vrrp_script chk_down {     script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"     interval 1 #每隔1秒检测一次#     weight -5 #权重减5# }  vrrp_script chk_nginx {     script "killall -0 nginx && exit 0 || exit 1" #检测nginx进程是否存在#     interval 1      weight -5     fall 2 #检测两次都不存在则降低权重#     rise 1 #检测一次存在则加权重# }  vrrp_instance VI_1 {     state MASTER     interface ens33     virtual_router_id 1         priority 100     advert_int 1     authentication {         auth_type PASS         auth_pass hello     }     virtual_ipaddress {         192.168.11.250 label ens33:0     }     #检测chk_down和chk_nginx两个脚本#     track_script {         chk_down         chk_nginx     }     notify_master "/etc/keepalived/notify.sh master"     notify_backup "/etc/keepalived/notify.sh backup"     notify_fault "/etc/keepalived/notify.sh fault" }  vrrp_instance VI_2 {     state BACKUP     interface ens33     virtual_router_id 2     priority 96     advert_int 1     authentication {         auth_type PASS         auth_pass world     }     virtual_ipaddress {         192.168.11.251 label ens33:1             }     track_script {         chk_down         chk_nginx     }     #定义触发通知脚本条件#     notify_master "/etc/keepalived/notify.sh master"     notify_backup "/etc/keepalived/notify.sh backup"     notify_fault "/etc/keepalived/notify.sh fault" }

3. 通知脚本内容如下：

    #!/bin/bash # contact='root@localhost' #定义函数：当主次节点发生变更之后给root@localhost发邮件通知# notify() {         local mailsubject="`hostname` to be $1,vip floating"         local mailbody="`data +"%F %T"`:vrrp transition,`hostname` changed to be $1"         echo "$mailbody" | mail -s "$mailsubject" $contact }  case $1 in master)         notify master         ;; backup)         notify backup         ;; fault)         notify fault         ;; *)         echo "Usage:$(basename $0) {master|backup|fault}"         exit 1         ;; esac