Google App Engine Task Queue REST API for the Java Development Server (devserver)

Question

I have a GAE app running on the Java Development Server (AKA devserver) on my local machine that defines some Task Queue pull queues.

I want to use the Task Queue REST API from a different standalone Java app, running on my machine, to access these pull queues.

I tried the sample suggested by Google's documentation that implements leasing tasks. Apparently, it uses the Google API Client Library for Java that requires a client_secrets.json file of the format:

{
  "installed": {
    "client_id": "retrieved from creating a Service Account for the project",
    "client_secret": "supposedly appears in the JSON file that's downloaded upon creation of a Service Account for the project"
  }
}

I created a Service Account for the project and a JSON was automatically downloaded, with the following format:

{
  "type": "service_account",
  "project_id": "myProjectId",
  "private_key_id": "some long hexadecimal",
  "private_key": "an even longer encrypted stuff",
  "client_email": "myServiceAccountName@myProjectId.iam.gserviceaccount.com",
  "client_id": "a decimal number",
  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
  "token_uri": "https://accounts.google.com/o/oauth2/token",
  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
  "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/myServiceAccountName%40myProjectId.iam.gserviceaccount.com"
}

In my client_secrets.json file I used private_key_id as the client_secret value and executed the sample code.

The result was that it opened https://accounts.google.com/o/oauth2/auth in my browser, which displayed an error with status code 400 and the following message:

Error: redirect_uri_mismatch Application: My Application The redirect URI in the request: http://localhost:61130/Callback did not match a registered redirect URI.

I tried Taskqueue.Builder.setRootUrl("http://localhost:8080"), although its javadoc says not to mess with it. It returned 401 Unauthorized.

1. Is there a way to use the Task Queue REST API from a standalone Java app to access these pull queues? I prefer using the Java libraries offered by Google but apparently they automatically point to the actual GAE services.
2. What should I use as the value of client_secret¹ in the client_secrets.json file when I do want to lease tasks from Google App Engine on the cloud?

---

^{1 When I created the Service Account, since I'm not the owner of the project, I got the following message:}

^{The service account could not be added to this project's permissions because you are not an owner of the project. To give the service account access to this project, ask a project owner to add it to the project permissions.}

^{I wonder whether this has something to do with the absence of a client_secret property in the automatically downloaded JSON.}

Answer 1

1. I don't think the dev server will expose the Task Queue API, do your tests against a separate test project that you create.

2. You can use the JSON from the service account to connect to the Task Queue API, see service accounts documentation.

   GoogleCredential credential = GoogleCredential.fromStream(new FileInputStream("MyProject-1234.json")) .createScoped(Collections.singleton("https://www.googleapis.com/auth/taskqueue"));

   Taskqueue taskQueue = new Taskqueue.Builder( httpTransport, JSON_FACTORY, credential).setApplicationName(APPLICATION_NAME) .setTaskqueueRequestInitializer(new TaskqueueRequestInitializer() { @Override public void initializeTaskqueueRequest(TaskqueueRequest request) { request.setPrettyPrint(true); } }).build();

   // get queue

   com.google.api.services.taskqueue.model.TaskQueue queue = getQueue(taskQueue); System.out.println(queue);

   // lease, execute and delete tasks

   Tasks tasks = getLeasedTasks(taskQueue);