[rant mode on]
The community is asking Java 8 support for the GAE . This month Oracle's official public support for Java 7 ends . It looks like there will be no side changes in the GAE before the end of the Java 7 lifecycle.
In addition, the GAE servlet container continues in version 2.5. There is a issue open 5 years ago, and nothing from Google updates Jetty from GAE to support more modern versions of the specification (3.0, 3.1, etc). That way, at least as far as the PaaS solution is concerned, we can already assume that the GAE-supported stack is legacy.
[rant mode off]
I own some applications that need evolution. These applications today rely heavily on Google services such as datastore, task queue, etc. Google's suggestion for developers in this situation is to migrate their environment to Custom Managed VMs , a middle ground between PaaS and IaaS in the style of Elastic Beanstalk .
That said, I did not find any documentation or post indicating how to use GAE Managed VMs with Java 8 (preferably in a modern container). Apparently this would involve a Dockerfile with dependencies on the GAE + Java stack services.
Someone who has already traced this Java 8 path in GAE with Managed VMs could shed light on how to put an environment to run (assuming this is possible)
An idea of what is needed to materialize the environment + a% of example% would come in handy.