www3838438 / flask-sslify

Force SSL on your Flask app.

Flask-SSLify

This is a simple Flask extension that configures your Flask application to redirect all incoming requests to HTTPS.

Redirects only occur when app.debug is False.

Usage

Usage is pretty simple:

from flask import Flask
from flask_sslify import SSLify

app = Flask(__name__)
sslify = SSLify(app)

If you make an HTTP request, it will automatically redirect:

$ curl -I http://secure-samurai.herokuapp.com/
HTTP/1.1 302 FOUND
Content-length: 281
Content-Type: text/html; charset=utf-8
Date: Sun, 29 Apr 2012 21:39:36 GMT
Location: https://secure-samurai.herokuapp.com/
Server: gunicorn/0.14.2
Strict-Transport-Security: max-age=31536000
Connection: keep-alive

HTTP Strict Transport Security

Flask-SSLify also provides your application with an HSTS policy.

By default, HSTS is set for one year (31536000 seconds).

You can change the duration by passing the age parameter:

sslify = SSLify(app, age=300)

If you'd like to include subdomains in your HSTS policy, set the subdomains parameter:

sslify = SSLify(app, subdomains=True)

Or by including SSLIFY_SUBDOMAINS in your app's config.

HTTP 301 Redirects

By default, the redirect is issued with a HTTP 302 response. You can change that to a HTTP 301 response by passing the permanent parameter:

sslify = SSLify(app, permanent=True)

Or by including SSLIFY_PERMANENT in your app's config.

Exclude Certain Paths from Being Redirected

You can exlude a path that starts with given string by including a list called skips:

sslify = SSLify(app, skips=['mypath', 'anotherpath'])

Or by including SSLIFY_SKIPS in your app's config.

Install

Installation is simple too:

$ pip install Flask-SSLify

Security consideration using basic auth

When using basic auth, it is important that the redirect occurs before the user is prompted for credentials. Flask-SSLify registers a before_request handler, to make sure this handler gets executed before credentials are entered it is advisable to not prompt for any authentication inside a before_request handler.

The example found at http://flask.pocoo.org/snippets/8/ works nicely, as the view function's decorator will never have an effect before the before_request hooks are executed.