What is the simplest to setup remote cache/execution server? I am preparing a demo and would like something as simple as possible 🙂

Bazel-remote for a cache. There's a plug and play docker image

I've been using this with much success. You can point the image at s3 and it works a treat. The pantsbuild repo uses that trick in its own github workflows.

See this job for an example of how we set it up