Day 57 Nginx负载均衡-高可用
Proxy 10.0.0.5
web01 10.0.0.7 #模拟iphone页面
web02 10.0.0.8 #模拟android页面
1.1 测试负载均衡
1.1.1 web01操作如下
[root@web01 conf.d]# cat sj.conf
server {
listen 80;
server_name sj.oldboy.com;
location / {
root /sj;
index index.html;
}
}
[root@web01 conf.d]# mkdir /sj
[root@web01 conf.d]# echo "Iphone....." >/sj/index.html
[root@web01 conf.d]# systemctl restart nginx
1.1.2 web02操作如下
[root@web02 conf.d]# cat sj.conf
server {
listen 80;
server_name sj.oldboy.com;
location / {
root /sj;
index index.html;
}
}
[root@web02 conf.d]# mkdir /sj
[root@web02 conf.d]# echo "Android...." > /sj/index.html
[root@web02 conf.d]# systemctl restart nginx
1.1.3 proxy操作
[root@lb01 ~]# cd /etc/nginx/conf.d/
[root@lb01 conf.d]# cat sj_proxy.conf
upstream iphone {
server 172.16.1.7:80;
}
upstream android {
server 172.16.1.8:80;
}
server {
listen 80;
server_name sj.oldboy.com;
location / {
if ($http_user_agent ~* "iphone"){
proxy_pass http://iphone;
}
if ($http_user_agent ~* "android"){
proxy_pass http://android;
}
}
}
[root@lb01 conf.d]# systemctl restart nginx
2.1 keepalived高可用概述
lb01:nginx负载均衡(完全一致)
lb02:nginx负载均衡(完全一致)
keepalived仅能实现地址漂移
2.2 什么是高可用
什么是高可用双击热备, 一般指2台机器启动着相同的业务系统,当有一台机器down机了, 另外一台服务器能快速的接管, 对于访问的用户是无感知的。
2.2.1 keepalived环境准备
服务器系统 角色 外网IP 内网IP
CentOS 7.5 keepalived-master eth0:10.0.0.5 eth1:172.16.1.5
CentOS 7.5 keepalived-slave eth0:10.0.0.6 eth1:172.16.1.6
2.2.2 在lb01与lb02上分别安装keepalived
[root@lb01 ~]# yum install keepalived -y
[root@lb02 ~]# yum install keepalived -y
2.2.3 配置lb01, keepalived-master
[root@lb01 ~]# cat /etc/keepalived/keepalived.conf
global_defs {
router_id lb01
}
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 50
priority 150
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
10.0.0.3
}
}
2.2.4 配置lb02, keepalived-backup
[root@lb02 ~]# cat /etc/keepalived/keepalived.conf
global_defs {
router_id lb02
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 50
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
10.0.0.3
}
}
2.2.5 对比keepalived的master与backup配置的区别
Keepalived配置区别 Master配置 Backup节配置
route_id(唯一标识) route_id lb01 route_id lb02
state(角色状态) state Master state Backup
priority(竞选优先级) priority 150 priority 100
2.2.6 keepalived+nginx负载均衡高可用
#lb01和lb02必须完完全全一致，这样才可以实现无缝切换
#快速配置一台负载均衡服务器
[root@lb02 ~]# scp -rp [email protected]:/etc/yum.repos.d /etc/
[root@lb02 ~]# yum install nginx -y
[root@lb02 ~]# scp -rp [email protected]:/etc/nginx /etc/
[root@lb02 ~]# systemctl start nginx
[root@lb02 ~]# systemctl enable nginx
2.3 Keepalived 高可用列脑
由于某些原因，导致两台keepalived高可用服务器在指定时间内，无法检测到对方的心跳消息，各自取得资源及服务的所有权，而此时的两台高可用服务器又都还活着。
服务器网线松动等网络故障
服务器硬件故障发生损坏现象而崩溃
主备都开启firewalld防火墙
Nginx服务死掉等
2.3.1 在备上编写检测脚本, 测试如果能ping通主并且备节点还有VIP的话则认为产生了列脑
[root@lb02 ~]# cat check_split_brain.sh
#!/bin/sh
lb01_vip=10.0.0.3
lb01_ip=10.0.0.5
while true;do
ping -c 2 -W 3 $lb01_ip &>/dev/null
if [ $? -eq 0 -a `ip add|grep "$lb01_vip"|wc -l` -eq 1 ];then
echo "ha is split brain.warning."
else
echo "ha is ok"
fi
sleep 5
done
1.只有在物理服务器的情况，并且公司的业务不允许DOWN机（7x24），才会使用keepalived
2.互联网公司
1.购买SLB->选择购买的连接数-->升级
2.自带高可用
2.自带高可用
ucloud负载均衡 ----> 迁移 --> 正常负载均衡
2.3.2 如果Nginx宕机, 会导致用户请求失败, 但Keepalived并不会进行切换, 所以需要编写一个脚本检测Nginx的存活状态, 如果不存活则kill nginx和keepalived
[root@lb01 ~]# mkdir /server/scripts
[root@lb01 ~]# vim /server/scripts/check_web.sh
#!/bin/sh
#使用while死循环
while true;do
nginxpid=$(ps -C nginx --no-header|wc -l)
#1.判断Nginx是否存活,如果不存活则尝试启动Nginx
if [ $nginxpid -eq 0 ];then
systemctl start nginx
sleep 5
#2.5秒后再次获取一次Nginx状态
nginxpid=$(ps -C nginx --no-header|wc -l)
#3.再次进行判断, 如Nginx还不存活则停止Keepalived,让地址进行漂移,并退出脚本
if [ $nginxpid -eq 0 ];then
systemctl stop keepalived
exit 1
fi
fi
sleep 5
done
[root@lb01 ~]# chmod +x /server/scripts/check_web.sh
在keepalived配置文件中调用此脚本，lb01与lb02都需操作
[root@lb01 ~]# cat /etc/keepalived/keepalived.conf
global_defs {
router_id LVS_01
}
vrrp_script check_web {
script "/server/scripts/check_web.sh"
interval 2
weight 50
}
vrrp_instance VI_1 {
state MASTER
interface ens33
virtual_router_id 51
priority 150
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
10.0.0.3/24 dev ens33
}
track_script {
check_web
}
}