It’s hard to tell with no cron.yaml,

It’s hard to tell with no cron.yaml, but I assume you’re trying to specify the GKE service/pod/whatever in your cron.yaml. No, you can’t ask GAE cron to access anything other than the GAE instance that you’re working with. So the only thing you can do is to specify a path in your GAE instance, and let the GAE handler access your GKE service/pod/whatever.