Day50
课堂笔记
5月10日
keepalved高可用实践
Keepalived的工作原理
1、安装keepalived（10.0.0.5/10.0.0.6）
yum install keepalived -y
rpm -qa keepalived
#keepalived-1.3.5-8.el7_6.x86_64
ls /etc/keepalived/keepalived.conf
2、配置主（10.0.0.5）
[root@lb01 keepalived]# cat keepalived.conf
global_defs {
router_id LVS_DEVEL
}
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 51
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
10.0.0.3/24 dev eth0 label eth0:1
}
}
3、配置备（10.0.0.6）
[root@lb02 ~]# cat /etc/keepalived/keepalived.conf
global_defs {
router_id LVS_BACKUP
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 51
priority 50
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
10.0.0.3/24 dev eth0 label eth0:1
}
}
主备区别：3点
router_id
state
priority
4、分别启动主备
systemctl start keepalived
[root@lb01 keepalived]# ps -ef|grep keep|grep -v grep
root 8613 1 0 20:58 ? 00:00:00 /usr/sbin/keepalived -D
root 8614 8613 0 20:58 ? 00:00:00 /usr/sbin/keepalived -D
root 8615 8613 0 20:58 ? 00:00:00 /usr/sbin/keepalived -D
5、测试
停掉主的keepalived，看备节点是否接管
恢复主的keepalived，看备节点是否释放
6、出错了 看日志
cat /var/log/messages
7、什么是裂脑？
split brain
高可用对之间每个机器同时接管VIP以及其他资源。
两端同时配置VIP了。
裂脑如何发生的？
1、心跳线出问题
2、防火墙阻挡心跳信息了。
实践演示裂脑：
如何防止裂脑？
配置10.0.0.6 nginx负载均衡
编译安装nginx负载均衡
下载：
mkdir -p /server/tools
cd /server/tools
wget http://nginx.org/download/nginx-1.16.0.tar.gz
#安装依赖。
yum install pcre pcre-devel -y
yum install openssl openssl-devel -y #https加密用他。
#编译安装步骤
tar xf nginx-1.16.0.tar.gz
cd nginx-1.16.0/
useradd -u 1111 -s /sbin/nologin nginx -M
id nginx
./configure --user=nginx --group=nginx --prefix=/application/nginx-1.16.0/ --with-http_stub_status_module --with-http_ssl_module --with-pcre
make
make install
ln -s /application/nginx-1.16.0/ /application/nginx
/application/nginx/sbin/nginx
netstat -lntup|grep nginx
curl 127.0.0.1
worker_processes 1;
events {
worker_connections 1024;
}
http {
include mime.types;
default_type application/octet-stream;
sendfile on;
keepalive_timeout 65;
upstream backend {
server 10.0.0.7:80 weight=1;
server 10.0.0.8:80 weight=1;
}
server {
listen 80;
server_name www.etiantian.org;
location / {
proxy_pass http://backend;
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $remote_addr;
proxy_connect_timeout 60;
proxy_send_timeout 60;
proxy_read_timeout 60;
proxy_buffer_size 4k;
proxy_buffers 4 32k;
proxy_busy_buffers_size 64k;
proxy_temp_file_write_size 64k;
}
}
server {
listen 80;
server_name blog.etiantian.org;
location / {
proxy_pass http://backend;
proxy_set_header Host $host;
}
}
server {
listen 80;
server_name img.etiantian.org img1.etiantian.org;
location / {
proxy_pass http://backend;
proxy_set_header Host $host;
}
}
}
方法1：
[root@lb01 scripts]# cat check_nginx.sh
#!/bin/sh
while true
do
if [ `netstat -lntup|grep nginx|wc -l` -ne 1 ];then
systemctl stop keepalived
fi
sleep 5
done
[root@lb01 scripts]# sh /server/scripts/check_nginx.sh &
方法2：
vrrp_script chk_nginx_proxy {
script "/server/scripts/check_nginx.sh"
interval 2
weight 2
}
track_script {
chk_nginx_proxy
}
ay 10 22:04:16 lb01 Keepalived_vrrp[9582]: Unable to access script `/server/scripts/check_nginx.sh`
May 10 22:04:16 lb01 Keepalived_vrrp[9582]: Disabling track script chk_nginx_proxy since not found