Configure Domain and Subdomain with Nginx on Ubuntu

Serve different apps with domains and subdomains in Nginx.

Modern web applications often require multiple entry points—perhaps a main site (example.com) and an admin dashboard (admin.example.com). Nginx, a high-performance web server, makes it straightforward to host different applications by mapping domains and subdomains to specific apps or directories. This guide will walk you through configuring both a domain and a subdomain with Nginx on Ubuntu.

Prerequisites

Root or sudo access to your Ubuntu server
Nginx installed (sudo apt install nginx)
Domains/subdomains pointing to your server (update DNS A records as needed)
Sample web app directories you want to serve

1. Directory Structure

Let’s assume you want:

The main app at: example.com (served from /var/www/example.com/html)
The admin panel at: admin.example.com (served from /var/www/admin.example.com/html)

Create the directories:

sudo mkdir -p /var/www/example.com/html
sudo mkdir -p /var/www/admin.example.com/html

Assign permissions:

sudo chown -R $USER:$USER /var/www/example.com/html
sudo chown -R $USER:$USER /var/www/admin.example.com/html

Create a simple index file to confirm:

echo "<h1>Welcome to example.com</h1>" > /var/www/example.com/html/index.html
echo "<h1>Welcome to admin.example.com</h1>" > /var/www/admin.example.com/html/index.html

2. Create Nginx Server Blocks

Nginx uses server blocks (similar to Apache “virtual hosts”) to serve different content based on the domain.

Navigate to the sites-available directory:

cd /etc/nginx/sites-available

Main Domain: `example.com`

Create a configuration file:

sudo nano /etc/nginx/sites-available/example.com

Insert the following:

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

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

    access_log /var/log/nginx/example.com.access.log;
    error_log  /var/log/nginx/example.com.error.log;

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

Subdomain: `admin.example.com`

Create a config for the subdomain:

sudo nano /etc/nginx/sites-available/admin.example.com

Add this content:

server {
    listen 80;
    server_name admin.example.com;

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

    access_log /var/log/nginx/admin.example.com.access.log;
    error_log  /var/log/nginx/admin.example.com.error.log;

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

3. Enable the Domain and Subdomain

To enable your configurations, create symbolic links from sites-available to sites-enabled:

sudo ln -s /etc/nginx/sites-available/example.com /etc/nginx/sites-enabled/
sudo ln -s /etc/nginx/sites-available/admin.example.com /etc/nginx/sites-enabled/

Remove the default configuration if you don’t need it:

sudo rm /etc/nginx/sites-enabled/default

4. Test and Reload Nginx

Before applying changes, verify that your config files are correct:

sudo nginx -t

If all’s well, reload Nginx:

sudo systemctl reload nginx

5. Verify Configuration

Try accessing:

Each should display the welcome message set previously.

6. (Optional) Secure with Let's Encrypt SSL

If you're going live, securing your sites with HTTPS is essential. The easiest way is via Certbot:

sudo apt install certbot python3-certbot-nginx
sudo certbot --nginx -d example.com -d www.example.com -d admin.example.com

Follow the prompts to complete SSL installation.

7. DNS Reminders

Don’t forget to set up your DNS records:

An A Record for example.com to your server IP
An A Record for admin.example.com to the same server IP

DNS changes can take some time to propagate.

Conclusion

Nginx makes hosting multiple apps easy by mapping domains and subdomains to different directories or backends. With just a few configuration tweaks, you can serve multiple applications from a single server—perfect for modern web development needs. For advanced scenarios, you can proxy to different backends, set up rate limits, or implement caching, all with Nginx’s powerful configuration options.

Happy hosting!