Good question pbowyer! We actually do a bunch of GraphQL parsing / calculations in the Compute@Edge layer. So without that, we would not be able to provide our current features.

We also support a feature we call "scopes" - where we both support cookies and headers in the "Vary" header so you can cache user-specific data only for the user with a specific "Authorization" header for example.

In order to support scopes with cookies, we needed Compute@Edge and could not make that work with VCL on its own. But believe me - we tried. Our first version was actually mostly built on top of VCL.

It's been awhile but IIRC you can't inspect the body on a POST request using Varnish. Either that or any real compute in Varnish gets super gnarly. I also think Fastly has a distributed K/V for state storage that you can access if you're using their new compute.

That is correct, you need to first transform the POST request into something Fastly can cache. They don't have a K/V Store besides the edge dictionaries with max 8kb value size yet, but I've heard something is coming...

Ah cool, thanks for the update. I haven't looked at their stuff in over a year. Congrats on the launch, looks really slick.