Here's the docs for the specific configuration parameters introduced (http2_push and http2_push_preload): https://nginx.org/en/docs/http/ngx_http_v2_module.html#http2...

What about caching? If the assets I want to push to browser are already cached in the browser would Nginx be smart enough to not to push?

Cache digests enables the browser to tell the server what’s cached so the server doesn’t push something unnecessarily: http://httpwg.org/http-extensions/cache-digest.html

In their intro to push they say to not push objects that are already cached so I'd wager no

Thanks, found this link about this which was pretty useful as someone who doesn't know much about this already; https://www.smashingmagazine.com/2017/04/guide-http2-server-...