Intermediate Level Module 6: Virtual Hosting

📚 Learning Objectives

By the end of this module, you will: - Understand advanced virtual hosting concepts - Configure name-based virtual hosting - Set up IP-based virtual hosting - Handle default servers - Configure wildcard domains - Set up subdomain management

🌐 Virtual Hosting Types

1. Name-Based Virtual Hosting

Multiple domains on one IP address (most common)

2. IP-Based Virtual Hosting

Different IP addresses for each domain

3. Port-Based Virtual Hosting

Different ports for different services

📋 Name-Based Virtual Hosting

Multiple domains share the same IP address:

# First domain
server {
    listen 80;
    server_name example.com www.example.com;
    root /var/www/example.com;
    index index.html;

    location / {
        try_files $uri $uri/ =404;
    }
}

# Second domain
server {
    listen 80;
    server_name another-site.com;
    root /var/www/another-site.com;
    index index.html;

    location / {
        try_files $uri $uri/ =404;
    }
}

How it works: - NGINX matches requests based on Host header - Same IP, different server_name values

🔌 IP-Based Virtual Hosting

Different IP addresses for different domains:

# Domain 1 on IP 192.168.1.10
server {
    listen 192.168.1.10:80;
    server_name example.com;
    root /var/www/example.com;
    # ...
}

# Domain 2 on IP 192.168.1.11
server {
    listen 192.168.1.11:80;
    server_name another-site.com;
    root /var/www/another-site.com;
    # ...
}

When to use: - SSL certificates requiring specific IPs - Legacy applications - Isolation requirements

🔢 Port-Based Virtual Hosting

Different ports for different services:

# Main website on port 80
server {
    listen 80;
    server_name example.com;
    root /var/www/example.com;
    # ...
}

# Development site on port 8080
server {
    listen 8080;
    server_name dev.example.com;
    root /var/www/dev;
    # ...
}

# Admin panel on port 8081
server {
    listen 8081;
    server_name admin.example.com;
    root /var/www/admin;
    # ...
}

🎯 Wildcard Domains

Subdomain Wildcard

server {
    listen 80;
    server_name *.example.com;
    root /var/www/wildcard;

    # Use the subdomain in config
    set $subdomain $1;
    if ($host ~* ^([^.]+)\.example\.com$) {
        set $subdomain $1;
    }

    location / {
        try_files $uri $uri/ =404;
    }
}

Catch-All Subdomain

server {
    listen 80;
    server_name *.example.com;
    root /var/www/subdomains;

    # Extract subdomain
    if ($host ~* ^([^.]+)\.example\.com$) {
        set $subdomain $1;
        rewrite ^(.*)$ /$subdomain$1 break;
    }
}

🏠 Default Server Blocks

Catch-All Default Server

# Default server - catches all unmatched requests
server {
    listen 80 default_server;
    server_name _;

    # Return 444 (close connection)
    return 444;

    # Or serve default page
    # root /var/www/default;
    # index index.html;
}

# Real websites
server {
    listen 80;
    server_name example.com;
    root /var/www/example.com;
    # ...
}

Multiple Default Servers

# Default for IPv4
server {
    listen 80 default_server;
    server_name _;
    return 444;
}

# Default for IPv6
server {
    listen [::]:80 default_server;
    server_name _;
    return 444;
}

📁 Organizing Virtual Hosts

Method 1: Separate Files

nginx.conf:

http {
    include /etc/nginx/mime.types;
    include /etc/nginx/conf.d/*.conf;
}

/etc/nginx/conf.d/example.com.conf:

server {
    listen 80;
    server_name example.com;
    # ...
}

Method 2: sites-available/sites-enabled

nginx.conf:

http {
    include /etc/nginx/mime.types;
    include /etc/nginx/sites-enabled/*;
}

/etc/nginx/sites-available/example.com:

server {
    listen 80;
    server_name example.com;
    # ...
}

Enable site:

sudo ln -s /etc/nginx/sites-available/example.com /etc/nginx/sites-enabled/
sudo nginx -t
sudo systemctl reload nginx

🌍 Subdomain Management

Individual Subdomain Configs

# Main domain
server {
    listen 80;
    server_name example.com;
    root /var/www/example.com;
    # ...
}

# www subdomain
server {
    listen 80;
    server_name www.example.com;
    return 301 http://example.com$request_uri;
}

# Blog subdomain
server {
    listen 80;
    server_name blog.example.com;
    root /var/www/blog;
    # ...
}

# API subdomain
server {
    listen 80;
    server_name api.example.com;

    location / {
        proxy_pass http://127.0.0.1:3000;
        # ...
    }
}

# Mail subdomain
server {
    listen 80;
    server_name mail.example.com;
    root /var/www/mail;
    # ...
}

Dynamic Subdomain Handling

server {
    listen 80;
    server_name ~^(?<subdomain>.+)\.example\.com$;

    # Use subdomain variable
    root /var/www/subdomains/$subdomain;

    location / {
        try_files $uri $uri/ =404;
    }
}

🔒 Secure Virtual Hosting

HTTPS Virtual Hosts

# HTTP redirect
server {
    listen 80;
    server_name example.com;
    return 301 https://$server_name$request_uri;
}

# HTTPS main
server {
    listen 443 ssl http2;
    server_name example.com;

    ssl_certificate /etc/nginx/ssl/example.com.crt;
    ssl_certificate_key /etc/nginx/ssl/example.com.key;

    root /var/www/example.com;
    # ...
}

Multiple HTTPS Domains

# Domain 1
server {
    listen 443 ssl http2;
    server_name example.com;

    ssl_certificate /etc/nginx/ssl/example.com.crt;
    ssl_certificate_key /etc/nginx/ssl/example.com.key;
    # ...
}

# Domain 2
server {
    listen 443 ssl http2;
    server_name another-site.com;

    ssl_certificate /etc/nginx/ssl/another-site.com.crt;
    ssl_certificate_key /etc/nginx/ssl/another-site.com.key;
    # ...
}

📝 Practical Examples

Example 1: Complete Multi-Domain Setup

# Default server
server {
    listen 80 default_server;
    server_name _;
    return 444;
}

# Main website
server {
    listen 80;
    server_name example.com www.example.com;

    # Redirect www to non-www
    if ($host = www.example.com) {
        return 301 http://example.com$request_uri;
    }

    root /var/www/example.com;
    index index.html;

    location / {
        try_files $uri $uri/ =404;
    }
}

# Blog subdomain
server {
    listen 80;
    server_name blog.example.com;
    root /var/www/blog;
    index index.html;

    location / {
        try_files $uri $uri/ =404;
    }
}

# API subdomain
server {
    listen 80;
    server_name api.example.com;

    location / {
        proxy_pass http://127.0.0.1:3000;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
    }
}

Example 2: Development and Production

# Production
server {
    listen 80;
    server_name example.com;
    root /var/www/example.com/production;
    # ...
}

# Staging
server {
    listen 80;
    server_name staging.example.com;
    root /var/www/example.com/staging;
    # ...
}

# Development
server {
    listen 8080;
    server_name dev.example.com;
    root /var/www/example.com/development;
    # ...
}

Example 3: User Subdomains

server {
    listen 80;
    server_name ~^(?<username>[a-z0-9-]+)\.example\.com$;

    root /var/www/users/$username;

    # Check if directory exists
    if (!-d $document_root) {
        return 404;
    }

    location / {
        try_files $uri $uri/ =404;
    }
}

🔍 Debugging Virtual Hosts

Test Server Name Matching

# Test specific host
curl -H "Host: example.com" http://your-server-ip

# Test default server
curl -H "Host: unknown.com" http://your-server-ip

Check Active Configuration

# Show all server blocks
sudo nginx -T | grep -A 10 "server {"

# Check which server block will match
sudo nginx -T | grep server_name

Debug with Headers

server {
    listen 80;
    server_name example.com;

    # Debug headers
    add_header X-Server-Name $server_name always;
    add_header X-Host $host always;
    # ...
}

📝 Exercises

Set up name-based virtual hosting for 3 domains
Configure IP-based virtual hosting
Set up port-based virtual hosting
Create a default server block
Configure wildcard subdomain handling
Set up multiple subdomains (www, blog, api)
Organize virtual hosts using separate files
Test server name matching

✅ Checklist

[ ] Understand virtual hosting types
[ ] Can configure name-based virtual hosting
[ ] Can set up IP-based virtual hosting
[ ] Can configure port-based virtual hosting
[ ] Understand default server blocks
[ ] Can handle wildcard domains
[ ] Can manage subdomains
[ ] Can organize virtual host configurations

➡️ Next Steps

Congratulations! You've completed the Intermediate Level. Proceed to Advanced Level - Module 1: Performance Tuning to learn about optimizing NGINX performance.