identify whether is code running on app engine runtime (Java)

Question

How can one identify whether some code (a serv-let or a simple class) is running on Google App Engine run-time (Java) so that one can decide whether to utilize app engine's specific libraries or not? Is there some reliable runtime enviroment ID for that?

Answer 1

You can check the com.google.appengine.runtime.version property:

String appEngineVersion = System.getProperty("com.google.appengine.runtime.version");

If it's set, it's App Engine.

But I would consider using separate build targets instead, to avoid the runtime overhead.

Answer 2

similar to what @Reza wrote, but a bit cleaner:

use SystemProperty.environment.value() to get "Production" when running on App Engine, and "Development" when running in the development server.