本文主要介绍了nginx+keepalived的部署实验，并简单说明了nginx的集中负载分担模式
简介：
nginx可以通过反向代理功能对后端服务器实现负载均衡功能
keepalived 是一种高可用集群选举软件
keepalived架构
分为三个模块：
1、keepalived core 核心模块
2、keepalived VRRP模块，加载vrrp协议，通过vrrp进行主备选举
——设置vrrp优先级，默认优先级100,
3、keepalive check检查模块，监控检查
——心跳检测，每一秒发送一次心跳
——备份节点如果三秒钟没有收到心跳信息，则认为主节点故障，备份节点切换为主节点
备份节点切换为主节点后，集群IP地址漂移到新的主节点 结合SMTP服务实现邮件发送
环境
VMwareworkstation 17 pro
CentOS Linux release 7.8.2003 (Core)
——4G内存，2core
——20G硬盘
——minimal安装
——NAT网络
#创建完web模板后进行克隆效率更高，随意#5节点部署，如图所示
搭建web节点
#搭建web节点
yum -y install httpd#修改主机名与html文件
hostnamectl set-hostname WEB1 && bash
echo web1 > /var/www/html/index.html
hostnamectl set-hostname WEB2 && bash
echo web2 > /var/www/html/index.html
hostnamectl set-hostname WEB3 && bash
echo web3 > /var/www/html/index.htmlsystemctl enable httpd --now#安全相关
systemctl disable firewalld --now
sed -i 's/^SELINUX=.*/SELINUX=disabled/' /etc/selinux/config
搭建nginx服务
#搭建nginx节点
hostnamectl set-hostname HA1 && bash
hostnamectl set-hostname HA2 && bash#安装软件包
yum -y install wget vim net-tools
wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo
yum -y install nginx nginx-mod-streamsystemctl enable nginx --now
netstat -tunlp | grep -i nginx # #验证
#tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 9482/nginx: master#安全相关
systemctl disable firewalld --now
sed -i 's/^SELINUX=.*/SELINUX=disabled/' /etc/selinux/confignginx服务配置
#nginx服务配置#备份，并且清除注释
cp /etc/nginx/nginx.conf /etc/nginx/nginx.conf.bak
sed -i 's/.*#.*//' /etc/nginx/nginx.conf
vim /etc/nginx/nginx.conf###配置文件含义
user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log;
pid /run/nginx.pid;
include /usr/share/nginx/modules/*.conf;events {worker_connections 1024; #worker进程上限
}http { #自身http服务的配置log_format main '$remote_addr - $remote_user [$time_local] "$request" ''$status $body_bytes_sent "$http_referer" ''"$http_user_agent" "$http_x_forwarded_for"';access_log /var/log/nginx/access.log main;sendfile on;tcp_nopush on;keepalive_timeout 65;types_hash_max_size 4096;include /etc/nginx/mime.types;default_type application/octet-stream;include /etc/nginx/conf.d/*.conf;server { #自己作为http服务器时的配置listen 80;listen [::]:80; #监听的ipv6的地址与端口server_name _;root /usr/share/nginx/html;include /etc/nginx/default.d/*.conf; error_page 404 /404.html; #出错之后的提示页面等location = /404.html {}error_page 500 502 503 504 /50x.html; location = /50x.html {}}
}###修改完成之后如下
#内含变量，建议vim，使用cat <<END或echo都会出错
user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log;
pid /run/nginx.pid;
include /usr/share/nginx/modules/*.conf;events {worker_connections 1024;
}stream {
log_format main '$remote_addr $upstream_addr - [$time_local] $status
$upstream_bytes_sent';
access_log /var/log/nginx/web_cluster.log main;upstream web_LB { #负载均衡设置server 192.168.8.162:80; #添加要转发的地址与端口server 192.168.8.163:80;server 192.168.8.164:80;}server {listen 80; #本地监听的端口，可以修改proxy_pass web_LB; # 设置为通过负载均衡web_LB的方式进行代理}
}#检查
nginx -t
#nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
#nginx: configuration file /etc/nginx/nginx.conf test is successful
nginx -s reload #重载配置文件此时重新访问，发现访问160和161能访问到后端的web服务器，清除缓存后会变化
最小连接
通过判断哪一个服务器的负载最小，选择负载最小的服务器进行连接
vim /etc/nginx/nginx.confupstream web_LB {
least_conn;
server 192.168.8.162:80;
server 192.168.8.163:80;
server 192.168.8.164:80;
}
nginx -t
nginx -s reload权重轮询
通过修改weight值，根据权重进行负载的分配
vim /etc/nginx/nginx.confupstream web_LB { #负载均衡设置
server 192.168.8.162:80 weight=1; #添加地址与端口
server 192.168.8.163:80 weight=2;
server 192.168.8.164:80 weight=3;
}
nginx -t
nginx -s reloadIPhash
根据源ip地址进行hash计算，根据计算值自动匹配到后端服务器
同个ip固定匹配一个服务器
适合流量大的时候使用，流量越多越均衡
vim /etc/nginx/nginx.confupstream web_LB {
hash $remote_addr consistent;
server 192.168.8.162:80;
server 192.168.8.163:80;
server 192.168.8.164:80;
}
nginx -t
nginx -s reloadHA节点搭建
#部署
yum install -y keepalived
cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bakvim /etc/keepalived/keepalived.conf
根据实际情况修改
###配置文件解析，并修改配置文件
! Configuration File for keepalivedglobal_defs {notification_email {acassen@firewall.locfailover@firewall.locsysadmin@firewall.loc}notification_email_from Alexandre.Cassen@firewall.locsmtp_server 127.0.0.1 #通过SMTP来发送邮件的地址smtp_connect_timeout 30router_id ha1 #路由器代号，挂了之后邮件提升的内容，主备节点需要不同，我写本机vrrp_skip_check_adv_addr#vrrp_strictvrrp_garp_interval 0vrrp_gna_interval 0
}
vrrp_instance VI_1 { #实例1，instance的概念与网络中的一致，可以设置多实例来允许多网段的访问state MASTER #状态interface ens33 #keepalived的接口地址，我的虚机网卡是ens33virtual_router_id 100 #虚拟地址路由器routerid，主备节点需要相同，建议自定义1-255priority 100 #优先级，主节点的需要比备节点高advert_int 1 #心跳间隔1sauthentication { #认证配置auth_type PASS #开启认证auth_pass 1111 #密钥}virtual_ipaddress { #虚拟的floating ip，支持多个192.168.8.200}
}#启动服务
systemctl enable keepalived --now
systemctl restart keepalived主节点的网卡会附带集群的地址，如下图
主备倒换测试
ha1停止keepalived，查看ha2的keepalived状态
systemctl stop keepalived
添加定时执行脚本自动拉活nginx
在keepalive的配置文件中添加脚本，用以检测nginx服务是否正常开启
通过脚本自动拉活nginx服务
vim /etc/keepalived/check_nginx_port.sh#!/bin/bash
if [ "$(netstat -ntlp | grep "nginx: master" | wc -l)" == "0" ]thensystemctl restart nginxsleep 2if [ "$(netstat -ntlp | grep "nginx: master" | wc -l)" == "0" ]thensystemctl stop keepalivedfi
fi编辑配置文件
vim /etc/keepalived/keepalived.conf...
vrrp_script check_nginx_port {script "/etc/keepalived/check_nginx_port.sh"interval 2 #间隔2秒
}...vrrp_instance VI_1 {...track_script {check_nginx_port}
}
