【nginx-keepalive】

负载均衡回顾

1.四层和七层的区别，实际环境;四层分流，七层根据域名负载到后端服务器

2.负载均衡的选择

nginx 四层和七层

LVS 四层 （nat,iptables）

HAproxy 四层和七层

F5 四层和七层

SLB 四层和七层

3.session

会话保持：ip_hash

会话共享：写入redis或mysql

写入浏览器：

手机客户端：

http {

......

upstream firefox {

server 172.31.57.133:80;

}

upstream chrome {

server 172.31.57.133:80;

}

upstream iphone {

server 172.31.57.133:80;

}

upstream android {

server 172.31.57.133:80;

}

upstream default {

server 172.31.57.133:80;

}

}

server {

listen 80;

server_name www.xuliangwei.com;

location / {

if ($http_user_agent ~* "Firefox") {

proxy_pass http://firefox;

}

if ($http_user_agent ~* "Chrome") {

proxy_pass http://chrome;

}

if ($http_user_agent ~* "iphone") {

proxy_pass http://iphone;

}

if ($http_user_agent ~* "android") {

proxy_pass http://andriod;

}

proxy_pass http://default;

include proxy_conf;

}

}

高可用

双机热备

hot standby

HSRP

VRRP

1.将所有设备加入到一个虚拟组

2.具有相同的虚拟IP

3.主机会在发送数据的时候，在数据包的目标地址写上虚拟的IP和MAC

4.虚拟组收到数据后，会将目标地址转换成当前虚拟组的master这个的IP和MAC

角色：一主多备

实际工作角色：主

通过优先级选举主备：越高越优先 最大值100

裂脑

keepalived高可用搭建

1.环境准备

2.安装软件

yum -y install keepalived

3.配置文件(router_ID, state priority不一样，其他都一样)

vim /etc/keepalived/keepalived.conf

global_defs {

router_id LB01 #LB02

script_user root

enable_script_security

}

vrrp_instance VI_1 {

state MASTER #BACKUP

interface eth0

virtual_router_id 51 #尽量设置成别的数字

priority 100 #90

adver_int 1

authentication {

auth_type PASS

auth_pass 1111

}

virtual_ipaddress {

10.0.0.3

}

}

systemctl start keepalived

systemctl enable keepalived

ip address #查看虚拟IP 是否存在于master上

ip add show dev eth 0

nmcli connection down eth 0 #down 主设备接口

高可用裂脑

网线松动、硬件故障，开启了firewalld,nginx服务不正常

解决方法

1.在备节点上编写脚本，测试如果能ping同主且备节点还有VIP，则认为是裂脑

-a #并且

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

ehco "ha is split bran.warining."

else

ehco "ha is ok"

fi

sleep 5

done

2.在主设备上，编写一个脚本检测，检测nginx的存活状态，如果不存活则kill nginx和keepalived

检测一次，开启nginx，再检测一次，如果不存活，则关闭keepalived

vim /server/scripts/check_web.sh

#!/bin/sh

while true;do

nginxpid=$(ps -C nginx --no-header|wc -l)

if [ $nginxpid -eq 0 ]; then

systemctl start nginx

sleep 5

nginxpid=$(ps -C nginx --no-header|wc -l)

if [ $nginxpid -eq 0 ];then

systemctl stop keepalived

exit 1

fi

fi

sleep 5

done

3.在keepalived配置文件中调用脚本，主备都需要操作

global_defs {

router_id LVS_01

}

vrrp_script check_web {

script "/server/scripts/check_web.sh"

interval 2

weight 50

}

vrrp_instance V1_1 {

track_script {

check_web

}

}

源码安装keepalived

1.下载源码

wget https://www.keepalived.org/software/keepalived-2.2.0.tar.gz --no-check-certificate

2.安装依赖

yum -y install openssl openssl-devel libnl* libnfnetlink-devel

3.编译安装

# 解压

tar -zxvf keepalived-2.2.0.tar.gz

# 进入目录

cd /server/soft/keepalived-2.2.0

# 创建安装目录

mkdir /usr/local/keepalived

# 配置安装目录

./configure --prefix=/usr/local/keepalived/

#编译

make && make install

4.配置

# 创建/etc/keepalived目录

mkdir /etc/keepalived

# 拷贝文件到目录

cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/

cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/

cp /usr/local/keepalived/sbin/keepalived /usr/sbin/

# 这个从keepalived源码目录复制，安装目录中没有

cp /server/soft/keepalived-2.2.0/keepalived/etc/init.d/keepalived /etc/rc.d/init.d/

# 开机启动

chkconfig keepalived on

service keepalived start #启动服务

service keepalived stop #停止服务

service keepalived restart #重启服务

service keepalived status #状态

#查看keepalived进程

ps -ef | grep keepalived

keepalived systemd 管理

[root@nginx001 scripts]# cat /usr/lib/systemd/system/keepalived.service

[Unit]

Description=LVS and VRRP High Availability Monitor

After=network-online.target syslog.target

Wants=network-online.target

[Service]

Type=forking

PIDFile=/run/keepalived.pid

KillMode=process

EnvironmentFile=-/etc/sysconfig/keepalived

ExecStart=/usr/local/keepalived/sbin/keepalived $KEEPALIVED_OPTIONS

ExecReload=/bin/kill -HUP $MAINPID

[Install]

WantedBy=multi-user.target

指定配置文件，配置文件错误，可能会报错 Fail to start LVS and VRRP Avaliability Monitor

cat /etc/sysconfig/keepalived

KEEPALIVED_Options="-f /etc/keepalived/keepalived.conf -D -S 0"

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