来自App Engine的Google Cloud Pubsub身份验证错误

我们无法将消息发布到Google AppEngine上的Google Cloud PubSub主题。使用应用程序默认凭据在本地完美工作。但是，一旦将它部署到Google AppEngine上，它会提供以下错误：

We're having trouble publishing messages to a Google Cloud PubSub topic on Google AppEngine. Using the Application Default credentials works perfect locally. But once it's deployed on Google AppEngine it gives the following error:

<HttpError 403 when requesting https://pubsub.googleapis.com/v1/projects/our-project-id/topics/our-topic:publish?alt=json returned "The request cannot be identified with a project. Please pass a valid API key with the request.">

我假设它会使用app引擎的服务帐户来访问PubSub API。

I would assume that it's will use the service account of app engine to access the PubSub API. Here is the code we used to create the credentials.

credentials = GoogleCredentials.get_application_default()
if credentials.create_scoped_required():
   credentials = credentials.create_scoped(['https://www.googleapis.com/auth/pubsub'])

http = httplib2.Http()
credentials.authorize(http)
pubsub_service = build('pubsub', 'v1', http=http)

将实际消息发布到PubSub时引发此错误。

The error is thrown when publishing the actual message to PubSub.

pubsub_service.projects().topics().publish(topic="projects/out-project-id/topics/out-topic", body = { 'messages' : [ { 'data': base64.b64encode(request.get_data()) }]}).execute()

不是说同一个流程将API调用用于 BigQuery ，所以这不是一般的Google API问题。这似乎是特定于PubSub ...

Not that the same flow works doing API call's to "BigQuery", so it's not a general Google API problem. It seems to be specific to PubSub...