Master Nginx: From Basics to Reverse Proxy, Load Balancing, and CORS

Introduction

This project is a minimal Nginx tutorial aimed at helping beginners quickly get started with Nginx.

What is Nginx?

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

What is a reverse proxy? A reverse proxy accepts client requests from the Internet, forwards them to internal servers, and returns the server responses to the clients.

Installation

See the detailed installation guide at https://github.com/dunwu/nginx-tutorial/blob/master/install-nginx.md .

Common Nginx commands:

nginx -s stop      # fast stop, may lose data
nginx -s quit      # graceful stop, saves state
nginx -s reload    # reload configuration
nginx -s reopen   # reopen log files
nginx -c filename # use a specific config file
nginx -t           # test config syntax only
nginx -v           # show version
nginx -V           # show version, compiler and configure options

You can create a startup.bat batch file on Windows to run these commands:

@echo off
rem if Nginx is already running and pid file exists, kill the process
nginx.exe -s stop
rem test config syntax
nginx.exe -t -c conf/nginx.conf
rem show version
nginx.exe -v
rem start with specified config
nginx.exe -c conf/nginx.conf

On Linux you can write a similar shell script.

HTTP Reverse Proxy

Basic configuration to proxy HTTP requests:

#user somebody;
worker_processes 1;
error_log D:/Tools/nginx-1.10.1/logs/error.log;
error_log D:/Tools/nginx-1.10.1/logs/notice.log notice;
error_log D:/Tools/nginx-1.10.1/logs/info.log info;
pid D:/Tools/nginx-1.10.1/logs/nginx.pid;

events {
    worker_connections 1024;
}

http {
    include D:/Tools/nginx-1.10.1/conf/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 D:/Tools/nginx-1.10.1/logs/access.log main;
    rewrite_log on;
    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:_WorkspaceProjectgithubzpSpringNotesspring-securityspring-shirosrcmainwebapp;
        charset utf-8;
        proxy_connect_timeout 180;
        proxy_send_timeout 180;
        proxy_read_timeout 180;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarder-For $remote_addr;
        location / {
            proxy_pass http://zp_server1;
        }
        location ~ ^/(images|javascript|js|css|flash|media|static)/ {
            root D:_WorkspaceProjectgithubzpSpringNotesspring-securityspring-shirosrcmainwebappiews;
            expires 30d;
        }
        location /NginxStatus {
            stub_status on;
            access_log on;
            auth_basic "NginxStatus";
            auth_basic_user_file conf/htpasswd;
        }
        location ~ /.ht {
            deny all;
        }
    }
}

Steps to test:

Start the webapp ensuring the upstream port matches.

Add a DNS entry in C:\Windows\System32\drivers\etc\hosts like 127.0.0.1 www.helloworld.com.

Run startup.bat.

Visit http://www.helloworld.com in a browser.

HTTPS Reverse Proxy

HTTPS uses port 443 and requires SSL certificates.

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;
    }
}

Load Balancing

Example using weighted round‑robin across three Linux servers:

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;
            client_max_body_size 10m;
            client_body_buffer_size 128k;
        }
    }
}

Supported strategies (shown as code snippets):

# round robin
upstream bck_testing_01 { server 192.168.250.220:8080; server 192.168.250.221:8080; server 192.168.250.222:8080; }

# weighted round robin
upstream bck_testing_01 { server 192.168.250.220:8080 weight=3; server 192.168.250.221:8080; server 192.168.250.222:8080; }

# least connections
upstream bck_testing_01 { least_conn; server 192.168.250.220:8080; server 192.168.250.221:8080; server 192.168.250.222:8080; }

# weighted least connections
upstream bck_testing_01 { least_conn; server 192.168.250.220:8080 weight=3; server 192.168.250.221:8080; server 192.168.250.222:8080; }

# ip_hash
upstream bck_testing_01 { ip_hash; server 192.168.250.220:8080; server 192.168.250.221:8080; server 192.168.250.222:8080; }

# hash by request URI
upstream bck_testing_01 { hash $request_uri; server 192.168.250.220:8080; server 192.168.250.221:8080; server 192.168.250.222:8080; }

Multiple Webapp Routing

When a site hosts several independent webapps (e.g., finance, product, admin), each runs on a different port and Nginx proxies based on URL context:

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

Static Site

Serve a static site from /app/dist:

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;
        }
    }
}

Add to hosts: 127.0.0.1 static.zp.cn and browse to the domain.

File Server

Simple file server with directory listing:

autoindex on;
autoindex_exact_size on;
autoindex_localtime on;

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

CORS Handling

Enable CORS via an include file enable-cors.conf:

# allow origin list
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"; }

Include it in the server block for API routes:

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;
    }
}

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

Author: dunwu

Link: https://github.com/dunwu/nginx-tutorial