Master Nginx: Reverse Proxy, Load Balancing, and HTTPS Configuration Guide

Overview

Nginx (engine x) is a lightweight web server, reverse proxy server, and mail (IMAP/POP3) proxy.

What is a Reverse Proxy?

A reverse proxy receives client requests from the Internet, forwards them to internal servers, and returns the server responses to the clients, appearing to the outside world as a single server.

Usage

Common Nginx commands:

<code>nginx -s stop       # Fast stop Nginx, may not save state and terminates immediately
nginx -s quit       # Graceful stop, saves state and shuts down orderly
nginx -s reload     # Reload configuration after changes
nginx -s reopen     # Reopen log files
nginx -c filename   # Use a specific configuration file instead of the default
nginx -t            # Test configuration syntax without starting the server
nginx -v            # Show Nginx version
nginx -V            # Show Nginx version, compiler version, and configure parameters</code>

For convenience on Windows you can create a

startup.bat

batch file:

<code>@echo off
rem If Nginx is already running and a PID file exists, kill the process
nginx.exe -s stop
rem Test configuration syntax
nginx.exe -t -c conf/nginx.conf
rem Show version information
nginx.exe -v
rem Start Nginx with a specific configuration
nginx.exe -c conf/nginx.conf</code>

On Linux a similar shell script can be used.

Nginx Configuration Practice

Example of a simple HTTP reverse proxy (no complex settings):

<code># user nobody;  # optional: run as a specific user
worker_processes 1;
error_log logs/error.log;
pid logs/nginx.pid;

events {
    worker_connections 1024;
}

http {
    include mime.types;
    default_type application/octet-stream;
    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 logs/access.log main;
    sendfile on;
    keepalive_timeout 120;
    tcp_nodelay on;

    upstream zp_server1 {
        server 127.0.0.1:8089;
    }

    server {
        listen 80;
        server_name www.helloworld.com;
        index index.html;
        root D:/01_Workspace/Project/github/zp/SpringNotes/spring-security/spring-shiro/src/main/webapp;
        charset utf-8;

        # Basic reverse proxy
        location / {
            proxy_pass http://zp_server1;
        }

        # Serve static files directly
        location ~ ^/(images|javascript|js|css|flash|media|static)/ {
            root D:/01_Workspace/Project/github/zp/SpringNotes/spring-security/spring-shiro/src/main/webapp/views;
            expires 30d;
        }

        # Status page
        location /NginxStatus {
            stub_status on;
            access_log on;
            auth_basic "NginxStatus";
            auth_basic_user_file conf/htpasswd;
        }

        # Deny access to hidden files
        location ~ /\.ht {
            deny all;
        }
    }
}
</code>

Load Balancing Configuration

When multiple backend servers are available, Nginx can distribute traffic using weighted load balancing:

<code>http {
    include /etc/nginx/mime.types;
    default_type application/octet-stream;
    access_log /var/log/nginx/access.log;

    upstream load_balance_server {
        server 192.168.1.11:80 weight=5;
        server 192.168.1.12:80 weight=1;
        server 192.168.1.13:80 weight=6;
    }

    server {
        listen 80;
        server_name www.helloworld.com;
        location / {
            root /root;
            index index.html index.htm;
            proxy_pass http://load_balance_server;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $remote_addr;
            proxy_connect_timeout 90;
            proxy_send_timeout 90;
            proxy_read_timeout 90;
            proxy_buffer_size 4k;
            proxy_buffers 4 32k;
            proxy_busy_buffers_size 64k;
            proxy_temp_file_write_size 64k;
            client_max_body_size 10m;
            client_body_buffer_size 128k;
        }
    }
}
</code>

Multiple Webapp Configuration

When a site hosts several independent web applications (e.g., finance, product, admin), each can run on a different port and be exposed through Nginx using context paths:

<code>http {
    upstream product_server { server www.helloworld.com:8081; }
    upstream admin_server   { server www.helloworld.com:8082; }
    upstream finance_server { server www.helloworld.com:8083; }

    server {
        # default to product
        location / { proxy_pass http://product_server; }
        location /product/ { proxy_pass http://product_server; }
        location /admin/   { proxy_pass http://admin_server; }
        location /finance/ { proxy_pass http://finance_server; }
    }
}
</code>

HTTPS Reverse Proxy Configuration

For sites requiring secure communication, configure Nginx to listen on port 443 with SSL certificates:

<code>server {
    listen 443 ssl;
    server_name www.helloworld.com;
    ssl_certificate     cert.pem;
    ssl_certificate_key cert.key;
    ssl_session_cache   shared:SSL:1m;
    ssl_session_timeout 5m;
    ssl_ciphers         HIGH:!aNULL:!MD5;
    ssl_prefer_server_ciphers on;

    location / {
        root /root;
        index index.html index.htm;
    }
}
</code>

Static Site Configuration

To serve a static website (HTML and assets) from a directory:

<code>worker_processes 1;

events { worker_connections 1024; }

http {
    include mime.types;
    default_type application/octet-stream;
    sendfile on;
    keepalive_timeout 65;
    gzip on;
    gzip_types text/plain application/x-javascript text/css application/xml text/javascript application/javascript image/jpeg image/gif image/png;
    gzip_vary on;

    server {
        listen 80;
        server_name static.zp.cn;
        location / {
            root /app/dist;
            index index.html;
            # redirect any request to index.html if needed
        }
    }
}
</code>

Add a host entry

127.0.0.1 static.zp.cn

and access the site via a browser.

File Server Setup

For a simple file server with directory listing:

<code>autoindex on;               # show directory listing
autoindex_exact_size on;   # show file sizes
autoindex_localtime on;     # show modification times

server {
    charset utf-8,gbk;
    listen 9050 default_server;
    listen [::]:9050 default_server;
    server_name _;
    root /share/fs;
}
</code>

CORS Solution

When front‑end and back‑end applications run on different ports, browsers block cross‑origin requests. Nginx can add the necessary CORS headers:

<code># enable-cors.conf
set $ACAO '*';
if ($http_origin ~* (www\.helloworld\.com)$) { set $ACAO $http_origin; }
if ($cors = "trueget") {
    add_header 'Access-Control-Allow-Origin' "$http_origin";
    add_header 'Access-Control-Allow-Credentials' 'true';
    add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
    add_header 'Access-Control-Allow-Headers' 'DNT,X-Mx-ReqToken,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type';
}
if ($request_method = 'OPTIONS') { set $cors "${cors}options"; }
if ($request_method = 'GET')     { set $cors "${cors}get"; }
if ($request_method = 'POST')    { set $cors "${cors}post"; }
</code>

Include the CORS fragment in the server block handling API requests:

<code>upstream front_server { server www.helloworld.com:9000; }
upstream api_server   { server www.helloworld.com:8080; }

server {
    listen 80;
    server_name www.helloworld.com;

    location ~ ^/api/ {
        include enable-cors.conf;
        proxy_pass http://api_server;
        rewrite "^/api/(.*)$" /$1 break;
    }

    location / {
        proxy_pass http://front_server;
    }
}
</code>

With these configurations, Nginx can serve as a reverse proxy, load balancer, static file server, HTTPS endpoint, and CORS gateway.