I have an AppEngine app with 2 services, where Service A is queueing tasks for Service B using the task (push) queue. How do I test this using the development server? When running multiple services with the development server, each service gets a unique port number, and the task queue can't resolve the URL because the target URL is actually running on another port, i.e. Service A is on port 8080 and Service B is on port 8081. This all works great in production where everything is on the same port, but how do I go about testing this locally?
The push queue configuration allows for specifying the target service by name, which the development server understands. From Syntax:
target (push queues)
Optional. A string naming a service/version, a frontend version, or a backend, on which to execute all of the tasks enqueued onto this queue.
The string is prepended to the domain name of your app when constructing the HTTP request for a task. For example, if your app ID is my-app and you set the target to my-version.my-service, the URL hostname will be set to my-version.my-service.my-app.appspot.com.
If target is unspecified, then tasks are invoked on the same version of the application where they were enqueued. So, if you enqueued a task from the default application version without specifying a target on the queue, the task is invoked in the default application version. Note that if the default application version changes between the time that the task is enqueued and the time that it executes, then the task will run in the new default version.
If you are using services along with a dispatch file, your task's HTTP request might be intercepted and re-routed to another service.
For example a basic queue.yaml would be along these lines:
queue:
- name: service_a
target: service_a
- name: service_b
target: service_b
I'm not 100% certain if this alone is sufficient, personally I'm also using a dispatch.yaml file as I need to route requests other than tasks. But for that you need to have a well-defined pattern in the URLs as host-name based patterns aren't supported in the development server. For example if the Service A requests use /service_a/... paths and Service B use /service_b/... paths then these would do the trick:
dispatch:
- url: "*/service_a/*"
service: service_a
- url: "*/service_b/*"
service: service_b
In your case it might be possible to achieve what you want with just a dispatch file - i.e. still using the default queue. Give it a try.