Google App Engine - Always running instance

Question

I want my App Engine to always have one instance running. I want to avoid that the first request after 15 minutes of no traffc takes like 20 seconds to finish. There is a feature called "Always on" that is mentioned several places to fix this, but I can't find it anywhere on App Engine.

I've tried to set min-idle-instances to 1 but it still starts a new instance after 15 minutes of no traffic. Any suggestions?

Answer 1

"Always-on" is deprecated (I believe it does not exist any more). The configurations that currently let you do that, and more, are documented at https://cloud.google.com/appengine/docs/java/modules/ ; for example if you always want one instance running, neither more nor less, set the default module of your app to manual scaling, with instances set to 1.

However, automatic scaling with min-idle-instances should also work if you have followed the instructions (at the URL I just gave)

For resident instances to function properly, you must be sure that warmup requests are enabled and your application handles warmup requests.

Use, again as that URL recommends, "The Availability column of the Developers Console Instance page" to check which of your instances are actually resident (as you wish) rather than dynamic (i.e, going away after some idle time).