Flask Allowed Hosts

This extension provides a way to restrict access to your Flask application based on the incoming request's hostname or IP address.

Features

• Restrict access by hostname/IP address.
• Per-route configuration options.
• Customize denied access behavior.
• Two usage options: class-based or decorator-based.

Installation

Install the package using pip:

pip install flask-allowed-hosts

Usage

Class-Based Usage

1. Initialize the AllowedHosts class.
2. Define allowed hosts (optional).
3. Define a function for denied access behavior (optional).
4. Apply access control to routes using @allowed_hosts.limit() decorator (optional).

Example:

from flask import Flask, jsonify, abort
from flask_allowed_hosts import AllowedHosts

app = Flask(__name__)

ALLOWED_HOSTS = ["93.184.215.14", "api.example.com"]


def custom_on_denied():
    error = {"error": "Oops! Looks like you are not allowed to access this page!"}
    return jsonify(error), 403


allowed_hosts = AllowedHosts(app, allowed_hosts=ALLOWED_HOSTS, on_denied=custom_on_denied)


# Allows all incoming requests
@app.route("/api/public", methods=["GET"])
def public_endpoint():
    data = {"message": "This is public!"}
    return jsonify(data), 200


# Only allows incoming requests from "93.184.215.14" and "api.example.com"
@app.route("/api/private", methods=["GET"])
@allowed_hosts.limit()
def private_endpoint():
    data = {"message": "This is private!"}
    return jsonify(data), 200


# We can override the allowed_hosts list and the on_denied function for each route
@app.route("/api/private/secret", methods=["GET"])
@allowed_hosts.limit(allowed_hosts=["127.0.0.1"], on_denied=lambda: abort(404))
def secret_private_endpoint():
    data = {"message": "This is very private!"}
    return jsonify(data), 200


if __name__ == '__main__':
    app.run(host='0.0.0.0', port=5000, debug=True)

Decorator-Based Usage (Legacy)

Warning: This approach might cause unexpected behavior when combined with the class-based usage.

1. Define allowed hosts (optional).
2. Define a function for denied access behavior (optional).
3. Apply access control to routes using @limit_hosts decorator.

Example:

from flask import Flask, jsonify
from flask_allowed_hosts import limit_hosts

app = Flask(__name__)

ALLOWED_HOSTS = ["93.184.215.14", "api.example.com"]


def custom_on_denied():
    error = {"error": "Custom Denied Response"}
    return jsonify(error), 403


# Allows all incoming requests
@app.route("/api/public", methods=["GET"])
def public_endpoint():
    data = {"message": "This is public!"}
    return jsonify(data), 200


# Only allows incoming requests from "93.184.215.14" and "api.example.com"
@app.route("/api/private", methods=["GET"])
@limit_hosts(allowed_hosts=ALLOWED_HOSTS, on_denied=custom_on_denied)
def private_endpoint():
    return jsonify({"message": "This is private!"}), 200

More Examples

You can find more examples in the examples directory.

Configuration

Initialization Parameters

• app: The Flask application instance (optional).
• allowed_hosts: List of allowed hosts (optional, defaults to None which allows all hosts).
• on_denied: Function for denied access behavior (optional).

Flask Config and Environment Variables

Flask Configuration

The extension respects these configurations:

• ALLOWED_HOSTS: List of allowed hosts in Flask config.
• ALLOWED_HOSTS_ON_DENIED: Function for denied access behavior in Flask config.

Precedence: Values provided during initialization override Flask config values.

Environment Variables

You can enable debug mode by setting the ALLOWED_HOSTS_DEBUG environment variable to True:

export ALLOWED_HOSTS_DEBUG="True"

This will print helpful debug messages to the console.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Support

If you have any questions or feedback, please feel free to open an issue or a pull request.

License

This project is licensed under the [MIT] License - see the LICENSE.md file for details.