Why am I getting a 403 error when attempting to access my google cloud bucket?

Question

I've have a bucket at a url something like: https://console.developers.google.com/storage/browser/gdfp-1234/

Then I created a project, named something like 'api-required' so I could generate credentials at /apis/credentials?project=api-required

Then, I generated a json service account key with the new_credentials button at /api/credentials/. I saved the json object I downloaded to a file that I pointed my environment variable GOOGLE_APPLICATION_CREDENTIALS at.

Now, I'm building an application in python. This code:

from gcloud import storage

gcs = storage.Client(project='my client n')
bucket = gcs.get_bucket(bucket_name)

Gives me a 403 Forbidden error.

Google Cloud Storage JSON API is in the Enabled API's list in the API Manager. This seems to cover everything in the docs.

I've been pouring over the docs, and cannot for the life of me figure out what I am doing wrong. Any help figuring this out would be greatly appreciated, thanks!

EDIT:
Here's the traceback:

/Users/asdf/.virtualenvs/analytics_pipeline/lib/python2.7/site-packages/gcloud/storage/client.pyc in get_bucket(self, bucket_name)
    165         """
    166         bucket = Bucket(self, name=bucket_name)
--> 167         bucket.reload(client=self)
    168         return bucket
    169 

/Users/asdf/.virtualenvs/analytics_pipeline/lib/python2.7/site-packages/gcloud/storage/_helpers.pyc in reload(self, client)
     75         api_response = client.connection.api_request(
     76             method='GET', path=self.path, query_params=query_params,
---> 77             _target_object=self)
     78         self._set_properties(api_response)
     79 

/Users/asdf/.virtualenvs/analytics_pipeline/lib/python2.7/site-packages/gcloud/connection.pyc in api_request(self, method, path, query_params, data, content_type, api_base_url, api_version, expect_json, _target_object)
    335         if not 200 <= response.status < 300:
    336             raise make_exception(response, content,
--> 337                                  error_info=method + ' ' + url)
    338 
    339         string_or_bytes = (six.binary_type, six.text_type)

Answer 1

So the bucket was accessible by a google group I belonged to, and the bucket was created by DFP because the bucket was full of DFP Data Transfer Files/Reports. To access their bucket, I had to add the email found in the json file I downloaded to the google group (Using the add member direct button, not the invite button). Once I added them to the google group everything worked like a charm.