How does App Engine affects the cost of using Cloud Datastore?

[Yihang Ho]

According to the Cloud Datastore documentation, "to use the Cloud Datastore API, your Cloud project requires an active App Engine application". Suppose that I am using only Cloud Datastore in my project, how does having an active App Engine application affect the cost of using Cloud Datastore?

[George (Cloud Platform Support)]

Hello Yihang, 

The App Engine application incurs costs when running. Billing begins when an instance starts and ends fifteen minutes after a manual instance shuts down or fifteen minutes after a basic instance has finished processing its last request. You may find more detail on the "App Engine Pricing" page. In other words, this mandatory app would not cost you, if your main application runs on a GCE instance. 

Datastore usage costs are calculated in terms of stored data, entity reads, entity writes, entity deletes, and small operations. None of these involve the active App Engine application, if the only use you make of the Datastore is from your GCE instance. 

[Ani Hatzis]

Hello George,

is it still necessary to create/deploy/enable an app in order to use a new datastore? To validate, I have created a new (empty) project. In Cloud Console under Cloud Datastore > Entities , after selecting a Datastore region, I was able to create an entity. I also could read this entity via REST API (API Explorer for projects.lookup). I didn't create an app. And there is also no hint or warning in Console that prompts me to create an app. Under App Engine > Dashboard I'm offered the "Your first app" flow.

Maybe the quote relates to features that are not (or were not) available without an app. Not sure, if composite index could be managed through the API or gcloud or by other means than deploying the index.yaml (or equivalent). And the old import & export worked only with an App Engine app while the new one doesn't seem to use the task queues and app instances.

[George (Cloud Platform Support)]

Engineering has been made aware of this situation, and will address it in due course. Meanwhile, you are encouraged to open a issue in the public tracker, so you may follow related developments there. 

[Yihang Ho]

Hi,

My application does not require Compute/App Engine. The only thing I need for this project is Cloud Datastore and accessing it from an outside network. In this case, does the active App Engine app that Cloud Datastore requires incur additional cost?

Thanks!

Yihang

[George (Cloud Platform Support)]

You cannot possibly get charged for an app that is not running. If you ensure that your mandatory App Engine app is not running, it won't attract any charges.  

[Yihang Ho]

Hi,

Got it. Thanks for the tip. In that case, how should I see the list of running App Engine apps?

Thanks!

Yihang

[George (Cloud Platform Support)]

Hi Yihang, 

To see a list of your apps in the app engine environment, you simply click on the triple-bar button at the top left of the page and select from the drop-down menu app engine ---> versions or instances. This does not seem to be a high priority for you, as you indicated that your main app runs on a GCE instance.