fix: support custom servers using HTTP/2 in production

[benmccann]

closes #11365

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@sveltejs/kit	Patch

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[Conduitry]

In #3572, we were able to check the major version of the incoming request and only operate on it then. Is that a possibility here, to avoid doing extra work cloning objects and looking for properties on every incoming request?

[benmccann]

done

I hadn't remembered that we had this before 😆 guess we should have kept it rather than merging #7142. perhaps undici has gotten stricter than it used to be

[teemingc]

This was something I tried in the previous PR but ran into some issues with the request URL being set incorrectly during https (#12907 (comment)). Can you verify if this works with HTTPS turned on during dev / preview while navigating around a SvelteKit website?

[Rich-Harris]

preview: https://svelte-dev-git-preview-kit-12989-svelte.vercel.app/

this is an automated message

[benmccann]

It should work now, but please test and let me know if it doesn't

[benmccann]

If we merge #12977 first it might help with testing

[teemingc]

LGTM. Managed to reproduce the issue I had earlier where the host was undefined during vite preview with HTTPS. To fix it, I replicated the HTTP2 host assignment logic from the vite/dev/index.js code to vite/preview/index.js.

kit/packages/kit/src/exports/vite/dev/index.js

Line 440 in 7a17bd2

req.headers[':authority'] || req.headers.host

kit/packages/kit/src/exports/vite/preview/index.js

Line 188 in 7a17bd2

const host = req.headers['host'];

[benmccann]

Awesome. Thanks for the help!