gistfile1.txt

from flask import Flask, current_app
from cryptography.hazmat.primitives import hashes
import base64
import confcollect
from acme import jose

DEFAULT_CONFIG = {
    'DEBUG': False,
    'ACCOUNT_THUMBPRINT_BASE64': '',
    'ACCOUNT_JSON': ''
}


def create_app():
    app = Flask(__name__)

    # Load config
    app.config.update(confcollect.from_environ(by_defaults=DEFAULT_CONFIG))

    # Get the thumbprint.
    if not app.config.get('ACCOUNT_THUMBPRINT_BASE64'):
        if not app.config.get('ACCOUNT_JSON'):
            raise ValueError('Needs either account thumbprint or account key')

        app.config['ACCOUNT_THUMBPRINT_BASE64'] = get_thumbprint(app.config['ACCOUNT_JSON'])
        print "Calculated account thumbprint: %s" % app.config['ACCOUNT_THUMBPRINT_BASE64']

    @app.route('/.well-known/acme-challenge/<id>')
    def respond(id):
        return "{}.{}".format(
            id,
            current_app.config['ACCOUNT_THUMBPRINT_BASE64']
        )

    return app


def get_thumbprint(account_json):
    """Given a Let's Encrypt account in JWRSA format, get it's
    thumbprint, encoded as base64.
    """
    key = jose.JWKRSA.json_loads(account_json)
    thumbprint = key.public_key().thumbprint(hashes.SHA256)
    return jose.b64encode(thumbprint)