Educational

Using HTTPS and SSL Certificates in Django

—

by

Saim Khalid
in

In today’s digital world, security is not an optional feature—it’s an absolute necessity. Whether you’re building a small blog or a large-scale web application, protecting user data should be your top priority. One of the most fundamental steps in securing your web app is using HTTPS (Hypertext Transfer Protocol Secure) instead of plain HTTP.

This article will guide you step by step through everything you need to know about enabling HTTPS on a Django web application using Let’s Encrypt and Certbot, along with an in-depth explanation of why HTTPS matters, how SSL/TLS certificates work, and how to configure Django for secure communication.

Table of Contents

  1. Understanding the Importance of HTTPS
  2. What Is an SSL/TLS Certificate?
  3. How HTTPS Works
  4. Why Every Django App Should Use HTTPS
  5. Prerequisites
  6. Setting Up Your Django App for HTTPS
  7. Installing Certbot for Let’s Encrypt SSL Certificates
  8. Obtaining an SSL Certificate with Certbot
  9. Configuring Nginx for HTTPS
  10. Updating Django Settings for Secure Communication
  11. Enforcing HTTPS Redirects
  12. Testing Your HTTPS Configuration
  13. Renewing Certificates Automatically
  14. Common SSL Issues and How to Fix Them
  15. Advanced HTTPS Security Settings for Django
  16. Using HTTPS in Local Development
  17. Conclusion

1. Understanding the Importance of HTTPS

HTTP is the traditional protocol used for transferring data between a client (browser) and a server. However, HTTP traffic is unencrypted, which means any attacker who intercepts the connection (for example, over public Wi-Fi) can view or manipulate the data.

HTTPS is the secure version of HTTP. It uses SSL/TLS encryption to protect all communication between the client and server. This means:

  • Data transmitted between browser and server is encrypted.
  • Attackers cannot easily eavesdrop on or tamper with data.
  • Users can verify that they’re connecting to the legitimate website, not an impostor.

Without HTTPS, sensitive data like passwords, credit card details, or session cookies can be easily stolen.

2. What Is an SSL/TLS Certificate?

An SSL/TLS certificate is a digital certificate issued by a Certificate Authority (CA) that verifies the ownership of a domain and enables encrypted communication over HTTPS.

Key points:

  • SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are cryptographic protocols that establish a secure channel.
  • When a user visits your website via HTTPS, their browser checks your SSL certificate to confirm it’s valid and issued for the correct domain.
  • Let’s Encrypt is a free, automated CA that makes SSL certificates easy to obtain and renew.

3. How HTTPS Works

Here’s a simplified step-by-step overview of how HTTPS works:

  1. Browser requests an HTTPS connection from the server.
  2. Server responds by sending its SSL certificate.
  3. Browser verifies the certificate with the issuing Certificate Authority (CA).
  4. If valid, the browser and server negotiate encryption keys for secure communication.
  5. All further communication is encrypted using those keys.

This process, called the SSL/TLS handshake, happens in milliseconds and ensures that all data transferred remains private and tamper-proof.

4. Why Every Django App Should Use HTTPS

Even if your application doesn’t handle sensitive data, you should still use HTTPS. Here’s why:

  • Data Integrity: Prevents data from being modified or corrupted during transfer.
  • Authentication: Ensures users are communicating with your legitimate server.
  • Privacy: Protects user data, sessions, and cookies.
  • SEO Benefits: Google ranks HTTPS-enabled sites higher.
  • Browser Warnings: Modern browsers mark HTTP sites as “Not Secure.”
  • Compliance: Many privacy laws and frameworks (GDPR, PCI-DSS) require encryption.

5. Prerequisites

Before setting up HTTPS, ensure you have:

  • A Django project deployed on a Linux server (Ubuntu recommended).
  • A domain name (e.g., yourdomain.com).
  • Nginx installed and configured as a reverse proxy for Django.
  • Root or sudo privileges on the server.

6. Setting Up Your Django App for HTTPS

First, make sure your Django app is running correctly on HTTP using Nginx and Gunicorn (or uWSGI). A typical setup might have:

  • Nginx serving as a reverse proxy.
  • Gunicorn running Django’s WSGI application.
  • Your site accessible at http://yourdomain.com.

Once that’s working, you’re ready to enable HTTPS.

7. Installing Certbot for Let’s Encrypt SSL Certificates

Let’s Encrypt provides free SSL certificates, and Certbot is the recommended tool to obtain and manage them automatically.

To install Certbot on Ubuntu, run:

sudo apt update
sudo apt install certbot python3-certbot-nginx

This installs both Certbot and the Nginx plugin that automates SSL configuration.

8. Obtaining an SSL Certificate with Certbot

Now that Certbot is installed, obtaining an SSL certificate is a single command away.

Run the following command (replace yourdomain.com with your actual domain):

sudo certbot --nginx -d yourdomain.com -d www.yourdomain.com

Certbot will:

  1. Verify that your domain points to your server.
  2. Obtain a free SSL certificate from Let’s Encrypt.
  3. Automatically configure Nginx for HTTPS.
  4. Ask whether you want to redirect HTTP traffic to HTTPS — choose “2: Redirect”.

If everything is configured correctly, you’ll see a message confirming successful installation and a note about when your certificate will expire.

9. Configuring Nginx for HTTPS

Certbot modifies your Nginx configuration automatically, but it’s useful to understand what’s happening under the hood.

Here’s an example of a secure Nginx configuration:

server {

listen 80;
server_name yourdomain.com www.yourdomain.com;
return 301 https://$host$request_uri;
}

server {

listen 443 ssl;
server_name yourdomain.com www.yourdomain.com;


ssl_certificate /etc/letsencrypt/live/yourdomain.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/yourdomain.com/privkey.pem;
include /etc/letsencrypt/options-ssl-nginx.conf;
ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem;


location = /favicon.ico { access_log off; log_not_found off; }
location /static/ {
    root /home/youruser/yourproject;
}


location / {
    include proxy_params;
    proxy_pass http://unix:/home/youruser/yourproject/yourproject.sock;
}
}

This configuration redirects all HTTP requests to HTTPS and uses the SSL certificates issued by Let’s Encrypt.

10. Updating Django Settings for Secure Communication

Next, update your Django settings to enforce secure communication. Open settings.py and add the following:

SECURE_SSL_REDIRECT = True
SESSION_COOKIE_SECURE = True
CSRF_COOKIE_SECURE = True

Explanation:

  • SECURE_SSL_REDIRECT = True — Redirects all HTTP requests to HTTPS automatically.
  • SESSION_COOKIE_SECURE = True — Ensures session cookies are only sent over HTTPS.
  • CSRF_COOKIE_SECURE = True — Ensures CSRF cookies are transmitted securely.

You can also enable additional security settings:

SECURE_BROWSER_XSS_FILTER = True
SECURE_CONTENT_TYPE_NOSNIFF = True
X_FRAME_OPTIONS = 'DENY'

These help mitigate XSS and clickjacking attacks.

11. Enforcing HTTPS Redirects

If you didn’t select the automatic redirect option during Certbot setup, you can manually enforce redirects.

Edit your Nginx HTTP server block:

server {

listen 80;
server_name yourdomain.com www.yourdomain.com;
return 301 https://$host$request_uri;
}

This ensures that any request to HTTP automatically redirects to HTTPS.

12. Testing Your HTTPS Configuration

After setting up HTTPS, test that everything works correctly.

  1. Restart Nginx: sudo systemctl restart nginx
  2. Visit your website using https://yourdomain.com.
  3. Look for the padlock icon in your browser’s address bar (indicating a secure connection).
  4. Test your SSL configuration using Qualys SSL Labs.

You should aim for an A or A+ rating.

13. Renewing Certificates Automatically

Let’s Encrypt certificates are valid for 90 days. Certbot can automatically renew them using a cron job or system timer.

Check automatic renewal:

sudo certbot renew --dry-run

If successful, it means your system will automatically renew certificates before expiration. You can also verify the cron job by checking:

sudo systemctl list-timers | grep certbot

14. Common SSL Issues and How to Fix Them

Even with automation, SSL issues may occur. Here are some common problems and solutions:

Problem 1: Domain Verification Fails

Solution:
Ensure your DNS A record correctly points to your server’s IP address.

Problem 2: Mixed Content Warnings

Solution:
This happens when some assets (like images or JavaScript) are still loaded via HTTP.
Fix by updating asset URLs to use HTTPS or relative URLs (//).

Problem 3: Expired Certificate

Solution:
Run sudo certbot renew manually or fix renewal cron jobs.

Problem 4: Permission Denied for Certificate Files

Solution:
Check Nginx permissions and ensure the certificate files in /etc/letsencrypt/live/ are readable by the web server.

15. Advanced HTTPS Security Settings for Django

Beyond the basics, Django provides additional security settings you should enable.

15.1 HSTS (HTTP Strict Transport Security)

HSTS forces browsers to use HTTPS for all future requests to your domain.

SECURE_HSTS_SECONDS = 31536000  # 1 year
SECURE_HSTS_INCLUDE_SUBDOMAINS = True
SECURE_HSTS_PRELOAD = True

15.2 Secure Referrer Policy

Control what referrer information is sent when users navigate from your site.

SECURE_REFERRER_POLICY = "same-origin"

15.3 Cookie Security

Ensure all cookies are transmitted securely and cannot be accessed by JavaScript.

SESSION_COOKIE_HTTPONLY = True
CSRF_COOKIE_HTTPONLY = True

16. Using HTTPS in Local Development

Even though HTTPS is mainly for production, it’s useful to simulate it locally for testing.

You can use mkcert or django-sslserver for local HTTPS development.

Option 1: Using django-sslserver

Install the package:

pip install django-sslserver

Add it to INSTALLED_APPS:

INSTALLED_APPS += ['sslserver']

Run the server with HTTPS:

python manage.py runsslserver

Now you can access your local Django app over https://localhost:8000.

Option 2: Using mkcert

Install mkcert to generate local certificates:

sudo apt install mkcert
mkcert -install
mkcert localhost

This creates localhost.pem and localhost-key.pem, which you can configure with your local Nginx or development server.

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