Gmail API Push Notifications gives Error 403

Question

I am trying to get push notifications regarding all the new inbox messages I receive in my email. I have configured the pubsub client as mentioned in the pubsub doc. Following is the code:

import httplib2

from apiclient import discovery
from oauth2client import client as oauth2client
from lib.common.models.main.users import User

from oauth2client.client import SignedJwtAssertionCredentials,\
    AccessTokenRefreshError

PUBSUB_SCOPES = ['https://www.googleapis.com/auth/pubsub']

def create_pubsub_client(http=None):
    credentials = oauth2client.GoogleCredentials.get_application_default()
    if credentials.create_scoped_required():
        credentials = credentials.create_scoped(PUBSUB_SCOPES)
    if not http:
        http = httplib2.Http()
    credentials.authorize(http)

    return discovery.build('pubsub', 'v1', http=http)

pubsub = create_pubsub_client()

topic = 'projects/<project-name>/topics/<Topic-name>'
policy = {
  'policy': {
    'bindings': [{
      'role': 'roles/pubsub.publisher',
      'members': ['serviceAccount:<my-service-account>'],
    }],
  }
}
resp = pubsub.projects().topics().setIamPolicy(resource=topic, body=policy).execute()

request = {
  'labelIds': ['INBOX'],
  'topicName': 'projects/<project-name>/topics/<Topic-name>'
}

f = file('link-to.p12', 'rb')
key = f.read()
f.close()

credentials = SignedJwtAssertionCredentials(
    'service-account-email',
    key,
    scope='https://mail.google.com/',
)

user = User.query.filter(User.id == 143).first()
accesskey = user.get_access_key(True)
credentials.access_token = accesskey['key']

service = discovery.build('gmail','v1',credentials=credentials)
service.users().watch(userId='me', body=request).execute()

When I run the above Program, I encounter the following error:

Traceback (most recent call last): File "/home/kmittal/workspace/engine/workers/newPubSubClient.py", line 82, in service.users().watch(userId='me', body=request).execute() File "/usr/local/lib/python2.7/dist-packages/oauth2client/util.py", line 135, in positional_wrapper return wrapped(*args, **kwargs) File "/usr/local/lib/python2.7/dist-packages/googleapiclient/http.py", line 723, in execute raise HttpError(resp, content, uri=self.uri) googleapiclient.errors.HttpError: https://www.googleapis.com/gmail/v1/users/me/watch?alt=json returned "Invalid topicName does not match projects/SOME_ANOTHER_PROJECT/topics/*">

Answer 1

As per this other answer, it looks like you can only create a watch for topics that are part of your own project, not another project. The documentation seems to back this up as it implies you must specify myproject (your own project ID):

The topic name can be any name you choose under your project (i.e. matching projects/myproject/topics/*, where myproject is the Project ID listed for your project in the Google Developers Console).