@ssl_required decorator for Flask on Heroku

gistfile1.py

from functools import wraps
from flask import request, redirect
import os

def https_required(f):
    @wraps(f)
    def decorated_function(*args, **kwargs):
        scheme = 'http'
        if request.headers.get('x-forwarded-proto', None):
            scheme = request.headers.get('x-forwarded-proto')

        if scheme == 'http' and os.environ.get('REALM', '') == 'prod':  # set REALM env variable from CLI
            newurl = request.url.replace('http://', 'https://')
            return redirect(newurl, 301)
        return f(*args, **kwargs)
    return decorated_function