一、简介
上一篇博文介绍了keepalived的高可用集群，其实使用nginx做前端代理，负载均衡照样可以实现双主或主备模式的高可用集群比起keepalived基于lvs的dr配置更为简单易学，下面是本人所理解的nginx高可用集群。此实验拓扑图类似keepalived拓扑，把图中keepalived字样换成nginx即可，我就不画了，有意者可重画。
实验拓扑图：
二、nginx主备模式高可用
配置nginx的upstream模块，让其反代到后端主机，后端主机配置和keepalived中雷同即可。
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upstream websrvs {
server 10.1.10.5:80; #后端主机real server01
server 10.1.10.6:80; #后端主机real server02
server 10.1.10.2:80 backup; #当后端主机均不能响应时此主机响应应急页面
}
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配置keepalived配置文件，实现VIP地址漂移
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! Configuration File for keepalived
global_defs {notification_email {}notification_email_from [email protected]smtp_server 127.0.0.1smtp_connect_timeout 30router_id node1vrrp_mcast_group4 224.0.100.18}vrrp_script chk_down {script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"
interval 1weight -5}vrrp_script chk_nginx {script "killall -0 nginx && exit 0 || exit 1"
interval 1weight -5}vrrp_instance VI_1 {state MASTERinterface eno16777736virtual_router_id 57priority 100advert_int 1authentication {auth_type PASSauth_pass 98181111}virtual_ipaddress {10.1.10.7/16 dev eno16777736
}track_script {chk_downchk_httpd}notify_master "/etc/keepalived/notify.sh master"
notify_backup "/etc/keepalived/notify.sh backup"
notify_fault "/etc/keepalived/notify.sh fault"
} |
实现图：
模拟单台后端主机无法提供服务及其全部宕机实验结果如下：
上诉结果可看出，此实验成功的展示了主备模式下的nginx反代，实现高可用。此实验课检测nginx的健康状态及其主备模式的切换时发邮件给管理员。
三、nginx主主模式高可用
配置keepalived配置文件，实现VIP地址漂移，和上诉主备相似
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! Configuration File for keepalived
global_defs {notification_email {}notification_email_from [email protected]smtp_server 127.0.0.1smtp_connect_timeout 30router_id node1vrrp_mcast_group4 224.0.120.18}vrrp_script chk_down { #检测此文件下是否存在down这个文件，灰度模式下上线时可使用此
script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"
interval 1weight -5}vrrp_script chk_nginx { #检测nginx的健康状态信息
script "killall -0 nginx && exit 0 || exit 1"
interval 1weight -5}vrrp_instance VI_1 {state MASTERinterface eno16777736virtual_router_id 53priority 100advert_int 1authentication {auth_type PASSauth_pass 9818sss1}virtual_ipaddress {10.1.10.7/16 dev eno16777736
}track_script {chk_downchk_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 BACKUPinterface eno16777736virtual_router_id 54priority 98advert_int 1authentication {auth_type PASSauth_pass 9818rss1}virtual_ipaddress {10.1.10.77/16 dev eno16777736
}track_script {chk_downchk_nginx}notify_master "/etc/keepalived/notify.sh master"
notify_backup "/etc/keepalived/notify.sh backup"
notify_fault "/etc/keepalived/notify.sh fault"
} |
此时，nginx上keepalived均启动结果如图：
模拟后端主机宕机及其恢复正常结果类似keepalived如图所示：
到此，nginx的高可用集群均已实现，做实验的方法和keepalived有很多相似之处。
本文转自chengong1013 51CTO博客，原文链接：http://blog.51cto.com/purify/1867871，如需转载请自行联系原作者