Chalice MP3 duration app

app.py

from io import BytesIO
from urllib2 import urlopen
from chalice import Chalice, BadRequestError
from mutagen.mp3 import MP3


app = Chalice(app_name='mp3info')


@app.route('/')
def index():
    request = app.current_request
    url = request.query_params.get('url')
    if url is None:
        raise BadRequestError('Usage: http://{0}/?url=http://url/to/file.mp3'.format(
            request.headers.get('Host')))
    try:
        u = urlopen(url)
    except Exception as e:
        raise BadRequestError(e.message)
    file_obj = BytesIO(u.read())
    mp3 = MP3(file_obj)
    info = mp3.info.__dict__
    return {'duration': info.get('length')}