Mastering Nginx: Reverse Proxy, Load Balancing, and High Availability Guide

Nginx Overview

Nginx is a high‑performance HTTP and reverse‑proxy server known for low memory usage and strong concurrency, capable of handling up to 50,000 simultaneous connections.

Reverse Proxy

Forward proxy : Clients inside a LAN must use a proxy server to access the Internet.

Reverse proxy: Clients send requests to the proxy without any configuration; the proxy forwards them to target servers and returns the responses, hiding the real server IP.

Load Balancing

When request volume grows, a single server cannot meet demand; adding more servers and distributing requests achieves load balancing.

Example: 15 requests are evenly split among three servers, each handling five requests.

Static‑Dynamic Separation

Separating static and dynamic content speeds up page rendering and reduces server load.

Before separation:

After separation:

Installation Reference

https://blog.csdn.net/yujing1314/article/details/97267369

Nginx Common Commands

./nginx -v

./nginx

./nginx -s stop
./nginx -s quit

./nginx -s reload

Configuration File Structure

The configuration file consists of three main blocks:

Global block : Settings that affect the entire Nginx process, including worker processes and connection limits.

Events block : Controls network connection handling, such as connection serialization and maximum connections.

HTTP block : Contains directives for reverse proxy, load balancing, etc.

Location directive syntax:

location [ = | ~ | ~* | ^~ ] url { }

= : exact match, stop searching.

~ : case‑sensitive regex.

~* : case‑insensitive regex.

^~ : prefix match with highest priority, stop further search.

Reverse Proxy Practical Example

1. Configure Nginx to forward

www.123.com

to a local Tomcat on port 8080.

2. Example configuration (images omitted for brevity).

3. Additional scenario: map

http://192.168.25.132:9001/edu/

to

192.168.25.132:8080

and

/vod/

to

192.168.25.132:8081

using regex location blocks.

Load Balancing Practical Example

Modify

nginx.conf

to define an upstream group and enable round‑robin distribution, then reload Nginx.

./nginx -s reload

Load‑balancing methods:

Round‑robin (default).

Weight – higher weight gets more requests.

Fair – based on backend response time.

ip_hash – same client IP always reaches the same backend (useful for session persistence).

Static‑Dynamic Separation Practical Setup

Configure Nginx to serve static files directly while proxying dynamic requests to Tomcat.

Key steps: place static assets in a separate directory, add

location /static/ { root /path/to/static; }

, and proxy other requests to the application server.

High Availability with Keepalived

Install Keepalived on two Nginx nodes and configure a virtual IP for failover.

[root@192 usr]# yum install keepalived -y
[root@192 usr]# rpm -q -a keepalived
keepalived-1.3.5-16.el7.x86_64

Sample

keepalived.conf

(excerpt):

global_defs {
    notification_email { [email protected] [email protected] [email protected] }
    notification_email_from [email protected]
    smtp_server 192.168.25.147
    smtp_connect_timeout 30
    router_id LVS_DEVEL
}

vrrp_script chk_nginx {
    script "/usr/local/src/nginx_check.sh"
    interval 2
    weight 2
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    virtual_router_id 51
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress { 192.168.25.50 }
}

Start the service:

systemctl start keepalived.service

When the primary node fails, the backup takes over the virtual IP, ensuring continuous service.

Conclusion

Typical Nginx deployment uses one master process and multiple worker processes; the number of workers should match CPU cores. Workers operate independently, so a failure in one does not affect the others, enabling hot deployment and high reliability.