How to configure Django allowed hosts?

Configuring Django Allowed Hosts

In Django, the ALLOWED_HOSTS setting is a security feature that specifies a list of host/domain names that the Django application is allowed to serve. This is an important configuration to ensure that your Django application is only accessible from the intended domains and to prevent potential security vulnerabilities.

Why is ALLOWED_HOSTS Important?

Django's security model includes a feature called "Host header validation," which checks the Host header of incoming HTTP requests to ensure that the request is coming from an authorized domain. This helps prevent a type of attack known as "Host header injection," where an attacker could potentially gain access to your Django application by sending a request with a malicious Host header.

By setting the ALLOWED_HOSTS configuration, you're telling Django which hosts are allowed to access your application. If a request comes in with a Host header that is not in the ALLOWED_HOSTS list, Django will raise a DisallowedHost exception, effectively blocking the request.

Configuring ALLOWED_HOSTS

The ALLOWED_HOSTS setting is a list of strings, where each string represents a host/domain name that your Django application is allowed to serve. Here's an example of how to configure ALLOWED_HOSTS in your Django project's settings.py file:

ALLOWED_HOSTS = ['example.com', 'www.example.com', '127.0.0.1', 'localhost']

In this example, the Django application will only serve requests that come from the example.com, www.example.com, 127.0.0.1 (localhost), and localhost domains.

If you're deploying your Django application to a hosting service or a cloud platform, you'll need to include the appropriate host/domain names in the ALLOWED_HOSTS list. For example, if you're using Heroku, you might have something like this:

import os

ALLOWED_HOSTS = ['your-app-name.herokuapp.com']

Here, 'your-app-name.herokuapp.com' would be the domain assigned to your Heroku application.

Using Wildcards in ALLOWED_HOSTS

You can also use wildcards in the ALLOWED_HOSTS setting to match multiple subdomains. For example, to allow all subdomains of example.com, you can use the following configuration:

ALLOWED_HOSTS = ['.example.com']

The leading dot ('.') in the string tells Django to match any subdomain of example.com.

Handling Dynamic Hosts

In some cases, you may need to handle dynamic hosts, such as when your Django application is running in a containerized environment or behind a load balancer. In these situations, you can use the * wildcard to match any host:

ALLOWED_HOSTS = ['*']

However, it's important to note that using the '*' wildcard is generally not recommended in production environments, as it can potentially expose your Django application to security risks. It's better to specify the exact hosts or subdomains that your application is allowed to serve.

Mermaid Diagram: ALLOWED_HOSTS Configuration

graph LR A[Django Application] --> B[ALLOWED_HOSTS] B --> C[example.com] B --> D[www.example.com] B --> E[127.0.0.1] B --> F[localhost] G[Heroku] --> H[your-app-name.herokuapp.com] I[Containerized Environment] --> J[*]

In conclusion, configuring the ALLOWED_HOSTS setting in your Django application is a crucial security measure to ensure that your application is only accessible from the intended domains. By carefully managing this setting, you can protect your Django application from potential security vulnerabilities and ensure that it is only served to authorized users.