第十三章?Nginx四层负载均衡

1、Nginx四层负载均衡概述

1.1、什么是四层负载均衡

四层负载均衡是基于传输层协议包来封装的（如：TCP/IP），那我们前面使用到的七层是指的应用层，他的组装在四层的基础之上，无论四层还是七层都是指的OSI网络模型。

1.2、四层负载均衡应用场景

1、四层+七层来做负载均衡，四层可以保证七层的负载均衡的高可用性；如：nginx就无法保证自己的服务高可用，需要依赖LVS或者keepalive。

2、如：tcp协议的负载均衡，有些请求是TCP协议的（mysql、ssh），或者说这些请求只需要使用四层进行端口的转发就可以了，所以使用四层负载均衡。

1.3、四层+七层构建大规模集群架构使用场景

1.4、四层负载均衡总结

• 四层负载均衡仅能转发TCP/IP协议、UDP协议、通常用来转发端口，如：tcp/22、udp/53；
• 四层负载均衡可以用来解决七层负载均衡端口限制问题；（七层负载均衡最大使用65535个端口号）
• 四层负载均衡可以解决七层负载均衡高可用问题；（多台后端七层负载均衡能同事的使用）
• 四层的转发效率比七层的高得多，但仅支持tcp/ip协议，不支持http和https协议；
• 通常大并发场景通常会选择使用在七层负载前面增加四层负载均衡。

1.5、nginx四层负载均衡场景实践

• 通过访问负载均衡的5555端口，实际是后端的web01的22端口在提供服务；
• 通过访问负载均衡的6666端口，实际是后端的mysql的3306端口在提供服务。

[root@lb02 ~]# cat /etc/yum.repos.d/nginx.repo

[nginx-stable]

name=nginx stable repo

baseurl=http://nginx.org/packages/centos/7/$basearch/

gpgcheck=0

enabled=1

gpgkey=https://nginx.org/keys/nginx_signing.key

#在lb02上安装nginx

[root@lb02 yum.repos.d]# yum install -y nginx

#在lb02上同步lb01的所有nginx相关配置

[root@lb02 ~]# scp -r root@172.16.1.5:/etc/nginx /etc/

#启动nginx

[root@lb02 conf.d]# nginx -t

nginx: the configuration file /etc/nginx/nginx.conf syntax is ok

nginx: configuration file /etc/nginx/nginx.conf test is successful

[root@lb02 conf.d]# systemctl enable nginx

Created symlink from /etc/systemd/system/multi-user.target.wants/nginx.service to /usr/lib/systemd/system/nginx.service.

[root@lb02 conf.d]# nginx

• 创建存放四层负载均衡配置文件的目录

[root@lb02 ~]# vim /etc/nginx/nginx.conf

user nginx;

worker_processes 1;

error_log /var/log/nginx/error.log warn;

pid /var/run/nginx.pid;

events {

worker_connections 1024;

}

events {

worker_connections 1024;

}

include /etc/nginx/conf.c/*.conf;

http {

include /etc/nginx/mime.types;

default_type application/octet-stream;

log_format main ‘$remote_addr - $remote_user [$time_local] "$r

equest" ‘

‘$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;

"/etc/nginx/nginx.conf" 33L, 677C written

[root@lb02 ~]# mkdir /etc/nginx/conf.c

• 配置四层负载均衡

[root@lb02 conf.c]# cat lb_domain.conf

stream {

upstream lb {

server 172.16.1.5:80 weight=5 max_fails=3 fail_timeout=30s;

server 172.16.1.6:80 weight=5 max_fails=3 fail_timeout=30s;

}

server {

listen 80;

proxy_connect_timeout 3s;

proxy_timeout 3s;

proxy_pass lb;

}

}

[root@web03 conf.c]# nginx -t

nginx: the configuration file /etc/nginx/nginx.conf syntax is ok

nginx: configuration file /etc/nginx/nginx.conf test is successful

[root@web03 conf.c]# nginx -s reload

#配置本机hosts解析后浏览器访问并查看nginx日志

• 四层负载均衡开启日志

[root@lb02 ~]# vim /etc/nginx/conf.c/lb_domain.conf

stream {

log_format proxy ‘$remote_addr $remote_port - [$time_local] $status $protocol ‘

‘"$upstream_addr" "$upstream_bytes_sent" "$upstream_connect_time"‘ ;

access_log /var/log/nginx/proxy.log proxy;

upstream lb {

server 172.16.1.9:80 weight=5 max_fails=3 fail_timeout=30s;

server 172.16.1.10:80 weight=5 max_fails=3 fail_timeout=30s;

}

server {

listen 80;

proxy_connect_timeout 3s;

proxy_timeout 3s;

proxy_pass lb;

}

}

~

~

~

~

~

"/etc/nginx/conf.c/lb_domain.conf" 16L, 463C written

[root@lb02 ~]# nginx -t

nginx: the configuration file /etc/nginx/nginx.conf syntax is ok

nginx: configuration file /etc/nginx/nginx.conf test is successful

1.6、nginx四层负载均衡端口转发

• 使用nginx四层负载均衡实现tcp的转发

请求负载均衡 5555 ---> 172.16.1.7:22;

请求负载均衡 6666 ---> 172.16.1.51:3306;

• 配置nginx四层负载均衡实现tcp的转发

[root@lb02 ~]# cat /etc/nginx/conf.c/lb_domain.conf

stream {

    log_format proxy ‘$remote_addr $remote_port - [$time_local] $status $protocol ‘

‘"$upstream_addr" "$upstream_bytes_sent" "$upstream_connect_time"‘ ;

    access_log /var/log/nginx/proxy.log proxy;

    upstream ssh_7 {

        server 10.0.0.207:22;

    }

    upstream mysql_51 {

        server 10.0.0.251:3306;

    }

    server {

        listen 5555;

        proxy_connect_timeout 3s;

        proxy_timeout 300s;

        proxy_pass ssh_7;

    }

    server {

        listen 6666;

        proxy_connect_timeout 3s;

        proxy_timeout 3s;

        proxy_pass mysql_51;

    }

}    

第十三章?Nginx四层负载均衡

原文：https://www.cnblogs.com/sunyuhang1/p/14492042.html