32.2nginx反向代理+keepalived高可用實驗
阿新 • • 發佈：2018-12-04
本節內容：
keepalived基於lvs，內建了lvs功能，實現了ipvsadm命令及lvs排程器的高可用性；而其它應用的高可用性keepalived提供了指令碼方式以供解決。如nginx作為反向代理伺服器時，不具備高可用性，利用keepalived的指令碼方式實現nginx的高可用性。
keepalived實現lvs的原理是基於vrrp協議(借鑑路由器的工作方式)，即一臺lvs伺服器實現排程，存在spof單點失敗問題，再搭建一臺lvs伺服器，實現主備，當主lvs宕機，啟動備用lvs即可實現高可用性。工作方式基於優先順序，優先順序高的自動為主lvs，又分為搶佔式和非搶佔式，即主lvs宕機，備用lvs成為主lvs，當原來宕機的主lvs修復後，誰當主的問題，預設搶佔模式，即原主修復後優先順序高，會重新成為主
keepalived基於指令碼呼叫介面通過執行指令碼完成指令碼中定義的功能，進而影響叢集事務， 以此支援nginx、haproxy等服務。這些是keepalived內建實現功能的原理，被開發keepalived的開發人員寫好了。而我們要實現其它服務，如nginx作為反向代理伺服器，則keepalived內建沒有此指令碼功能，但keepalived支援指令碼呼叫。需要我們自己寫指令碼，通過keepalived呼叫自定義指令碼實現高可用性
實驗：keepalived實現主主 nginx反向代理的高用性
rs伺服器準備
[root@cos27 ~ ]#hostnamectl set-hostname rs1
[root@cos37 ~ ]#hostnamectl set-hostname rs2
[root@cos27 ~ ]#exit
[root@cos37 ~ ]#exit
[root@rs1 ~ ]#yum install httpd -y
[root@rs2 ~ ]#yum install httpd -y
[root@rs1 ~ ]#systemctl start httpd
[root@rs2 ~ ]#systemctl start httpd ka和nginx代理配置
HA Cluster 配置準備：
(1) 各節點時間必須同步
ntp, chrony
(2) 確保iptables及selinux不會成為阻礙
(3) 各節點之間可通過主機名互相通訊（對KA並非必須）
建議使用/etc/hosts檔案實現
(4) 各節點之間的root使用者可以基於金鑰認證的ssh服務完成互相通訊（對KA並非必須）
[root@ka1 ~ ]#yum install keepalived
[root@ka2 ~ ]#yum install keepalived
[root@ka1 ~ ]#yum install nginx -y
[root@ka2 ~ ]#yum install nginx -y
[root@cos7 ~ ]#hostnamectl set-hostname ka1
[root@cos17 ~ ]#hostnamectl set-hostname ka2
[root@cos7 ~ ]#exit
[root@cos17 ~ ]#hxit
[root@ka1 ~ ]#cd /etc/keepalived/
[root@ka1 ~ ]#ssh-genkey
[root@ka1 ~ ]#ssh-copy-id 192.168.31.17
[root@ka1 ~ ]#ssh-genkey
[root@ka2 ~ ]#ssh-copy-id 192.168.31.7
[root@ka1 keepalived ]#vim /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 ka1
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
192.168.31.17 ka1
[root@ka2 etc ]#vim /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 ka2
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
192.168.31.7 ka1 nginx反向代理配置
[[email protected] ~ ]#vim /etc/nginx/nginx.conf
#新增或者修改如下配置
http {
upstream websrvs{ #反向代理
server 192.168.31.27:80;
server 192.168.31.37:80;
}
upstream websrvs2{
server 192.168.31.47:80;
server 192.168.31.57:80;
}
server {
listen 80 default_server;
listen [::]:80 default_server;
server_name www.dhy.com;
location / {
proxy_pass http://websrvs ;
}
}
server {
listen 80;
server_name app.dhy.com;
location / {
proxy_pass http://websrvs2 ;
}
}
[[email protected] ~ ]#vim /etc/nginx/nginx.conf
同上ka1，ka2高可用性配置
[[email protected] ~ ]#vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
[email protected]
}
notification_email_from [email protected]
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id ka1 #ka2上修改為ka2
vrrp_mcast_group4 230.10.10.10
}
vrrp_script chk_nginx {
script "/usr/bin/killall -0 nginx &> /dev/null "
interval 1
weight -30
# fall 2
# rise 1
}
vrrp_instance VI_1 {
state MASTER #ka2修改為BACKUP
interface eth1
virtual_router_id 50
priority 100 #ka2上修改為80
advert_int 1
authentication {
auth_type PASS
auth_pass 123456
}
virtual_ipaddress {
172.18.0.100/16
}
track_script {
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 #ka2上修改為MASTER
interface eth1
virtual_router_id 60
priority 80 #ka2上修改為100
advert_int 1
authentication {
auth_type PASS
auth_pass 654321
}
virtual_ipaddress {
172.18.0.200/16
}
track_script {
chk_nginx
}
notify_master "/etc/keepalived/notify.sh master"
notify_backup "/etc/keepalived/notify.sh backup"
notify_fault "/etc/keepalived/notify.sh fault"
}
[[email protected] ~ ]#vim /etc/keepalived/notify.sh
#!/bin/bash
#
contact='[email protected]'
notify() {
mailsubject="$(hostname) to be $1, vip floating"
mailbody="$(date +'%F %T'): vrrp transition, $(hostname) changed to be $1"
echo "$mailbody" | mail -s "$mailsubject" $contact
}
case $1 in
master)
notify master
systemctl start nginx
;;
backup)
notify backup
systemctl restart nginx
;;
fault)
notify fault
;;
*)
echo "Usage: $(basename $0) {master|backup|fault}"
exit 1
;;
esac啟動服務，測試
[root@ka1 ~ ]#systemctl start keepalived.service nginx.service
[root@ka2 ~ ]#systemctl start keepalived.service nginx.service
[root@client ~ ]#vim /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 client
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
172.18.0.100 www.dhy.com
172.18.0.200 app.dhy.com
[root@client ~ ]#curl www.dhy.com
rs1:192.168.31.27
[root@client ~ ]#curl www.dhy.com
rs2:192.168.31.37
[root@client ~ ]#for i in {1..100};do curl www.dhy.com;curl app.dhy.com;sleep 2;done
rs2:192.168.31.37
app.dhy.com:rs1
rs1:192.168.31.27
app.dhy.com:rs2
rs2:192.168.31.37
app.dhy.com:rs2
curl: (7) couldn't connect to host #[[email protected] ~ ]#killall nginx
app.dhy.com:rs1
rs1:192.168.31.27
app.dhy.com:rs2
rs2:192.168.31.37
app.dhy.com:rs1
rs1:192.168.31.27
app.dhy.com:rs1
rs2:192.168.31.37