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 {
root@localhost
}
notification_email_from keepalived@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id node1
vrrp_mcast_group4 224.0.100.18
}
vrrp_script chk_down {
script
"[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"
interval 1
weight -5
}
vrrp_script chk_nginx {
script
"killall -0 nginx && exit 0 || exit 1"
interval 1
weight -5
}
vrrp_instance VI_1 {
state MASTER
interface eno16777736
virtual_router_id 57
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 98181111
}
virtual_ipaddress {
10.1.10.7
/16
dev eno16777736
}
track_script {
chk_down
chk_httpd
}
notify_master
"/etc/keepalived/notify.sh master"
notify_backup
"/etc/keepalived/notify.sh backup"
notify_fault
"/etc/keepalived/notify.sh fault"
}
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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 {
root@localhost
}
notification_email_from keepalived@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id node1
vrrp_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 1
weight -5
}
vrrp_script chk_nginx {
#检测nginx的健康状态信息
script
"killall -0 nginx && exit 0 || exit 1"
interval 1
weight -5
}
vrrp_instance VI_1 {
state MASTER
interface eno16777736
virtual_router_id 53
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 9818sss1
}
virtual_ipaddress {
10.1.10.7
/16
dev eno16777736
}
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 eno16777736
virtual_router_id 54
priority 98
advert_int 1
authentication {
auth_type PASS
auth_pass 9818rss1
}
virtual_ipaddress {
10.1.10.77
/16
dev eno16777736
}
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"
}
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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
