AppEngine: Java, Python or Go? Personally I prefer Python because I haven't gotten into Go, and Java is a headache at times..

What do you guys think about deploying elastic search on App Engine Custom Runtime?

(Basically, an empty folder with an elastic search Dockerfile.)

I think it's a good idea: you can now deploy your code and storage application (Elastic search, Redis, etc) as services on your cluster.

You can use GCP magic to auto scale those services, you have so many good stuff that come with it.

And it's inside the same network as your services running in the same AppEngine project.