I know about the [[statics]] config section and it’s been working fine, but it looks like there’s no way to change the Cache-Control (or any other) header in the response from the CDN, even for hashed/versioned assets that can be cached immutably. In addition, from my testing, fly does not appear to cache responses from my Fly origin container with a Cache-Control header via the CDN, i.e. every new client will re-request the document from the server, which makes it impossible to easily optimize expensive server-side logic or rarely changing pages using cache headers.
Did I misconfigure something, or is this “dynamic origin cache” functionality not there yet? If so, are there plans to address this? ʕ·͡ᴥ·ʔ
Right now there’s no way to set these headers. statics is not really a CDN - we just pluck files out of your build and serve them so your app doesn’t have to.
S we don’t have plans to extend the statics feature now, but we’re always thinking about ways we can help people avoid having to use CDNs. 
Depending on your runtime, you may already have tools that help you cache expensive operations without resorting to another tool like a CDN. That said, it’s easy run an HTTP cache in front of your app on Fly - especially if you do not need to expire content explicitly.
Lastly, f your app can run in multiple regions, you’ll get a perf boost for both static and dynamic requests being served closer to your users.
This was a long answer to a simple question, but we’re happy to expand on any of these topics!