Failed to bind to $PORT when trying to deploy Python/flask app to Heroku

Question

I'm trying for the first time to remotely deploy my Python flask web app on Heroku and of course I'm encountering some problems. My python code looks like this:

# server settings
HOST = '127.0.0.1'
PORT = int(os.environ.get('PORT', 5000))
DEBUG_MODE = True
...
#functions definition
...
app = Flask(__name__)

@app.route("/geodesicDistance")
def geodesicDistance():
    t_start = time.time()
    query = parse_query(request.args)
    if query:
        position = geocode_address(query)
         if (position) and (len(position[u'results'])>0):
            lat = position[u'results'][0][u'geometry'][u'location'][u'lat']
            lng = position[u'results'][0][u'geometry'][u'location'][u'lng']
            response = create_response(200,
                                       'Good query',
                                       lat,
                                       lng,
                                       position[u'results'][0][u'formatted_address'],
                                       get_distance(lat,lng)
                                       )
        else:
            response = create_response(400,
                                       'Bad formed query',
                                       '',
                                       '',
                                       '',
                                       '')
    else:
        response = create_response(204,
                                   'No query made',
                                   givenAddress['lat'],
                                    givenAddress['lng'],
                                   'White Bear Yard, 144a Clerkenwell Road, London,                              EC1R 5DF, UK',
                                   0.0
                                   )
    response['result']['elapsed'] = (time.time() - t_start)*1.0e3
    http_response = make_response(json.dumps(response))
    http_response.headers['Content-type'] = 'application/json'
    http_response.headers['Access-Control-Allow-Origin'] = '*'
    return http_response

if __name__=="__main__":
  app.run(debug=DEBUG_MODE, host=HOST, port=PORT)

And my JavaScript:

<script type="text/javascript">
    function checkGeolocation() {
        if (navigator.geolocation) {
            refresh();
        } else {
           $('#results')[0].innerHTML = "<p>Your browser doesn't support geolocation <br /></p>";
               }
        }

        function getDistance(position) {
            url = 'http://127.0.0.1:5000/geodesicDistance';
            query  =position.coords.latitude.toString()+','+position.coords.longitude.toString();
                     $.get(url, {'q': query},function(data) {
                         $('#results .distance')[0].innerHTML = Math.round(data['result']['distance']*1000)/1000;

                     })
                 }

      function handleError(error) {
         alert(error.message);
      }

      function refresh() {
          navigator.geolocation.getCurrentPosition(getDistance,handleError);
       }

         $(document).ready(function(){
             checkGeolocation();
          });
</script>

This is the error Heruku gives according to the logs

2013-08-21T00:12:55.985496+00:00 heroku[web.1]: Starting process with command `python         geodesicDistance.py`
2013-08-21T00:12:57.326395+00:00 app[web.1]:  * Running on http://127.0.0.1:12176/
2013-08-21T00:12:57.326395+00:00 app[web.1]:  * Restarting with reloader
2013-08-21T00:13:56.914333+00:00 heroku[web.1]: Error R10 (Boot timeout) -> Web process     failed to bind to $PORT within 60 seconds of launch
2013-08-21T00:13:56.914595+00:00 heroku[web.1]: Stopping process with SIGKILL
2013-08-21T00:13:58.185305+00:00 heroku[web.1]: Process exited with status 137
2013-08-21T00:13:58.205874+00:00 heroku[web.1]: State changed from starting to crashed
2013-08-21T00:18:23.999482+00:00 heroku[router]: at=error code=H10 desc="App crashed"      method=GET path=/ host=stormy-sands-9363.herokuapp.com fwd="93.46.195.73" dyno= connect=  service= status=503 bytes=

I believe it's a port problem and the cause may be this line in my javascript code

url = 'http://127.0.0.1:5000/geodesicDistance';

not having the possibility to set a static port with Heroku

My Procfile (it's working in local)

Web: python geodesicDistance.py

Any advice?

Answer 1

if you look at this page https://devcenter.heroku.com/articles/dynos (search for "web dynos") you see that Heroku sets the environment variable $PORT So, even if you can't specify the port Flask will run on, you can at least know it from the $PORT variable.