http2 vs http1 support seems backwards

[moonmeister]

Prerequisites

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Issue

So, in everything I've read, but most importantly, the Chrome docs, Early Hints are only supported on http2 and 3. But, this plugin throws an error if I try to set Fastify to use http2.

Is this not backwards? If correct as is, what's the reason we've disabled this on http/2? Thanks all!

[climba03003]

Is this not backwards?

It is the choice from Chromium and it does not means Early Hints is not supported in HTTP/1.1.

What's the reason we've disabled this on http/2?

I believe is the complexity of directly write to socket for HTTP/2.

[Uzlopak]

Also we expect that fastify is behind a reverse proxy like Ingress/traefik which resolves a http2 request to http1.1 and vice versa.

Maybe we can transplant http2 from nodejs sourcecode to our plugin?

[climba03003]

Maybe we can transplant http2 from nodejs sourcecode to our plugin?

Yes, we can use reply.raw.stream for the reply.
Details on https://nodejs.org/api/http2.html#http2streamadditionalheadersheaders

[mcollina]

I think we should just use the native functionality: https://nodejs.org/api/http2.html#responsewriteearlyhintslinks.

[climba03003]

I think we should just use the native functionality: https://nodejs.org/api/http2.html#responsewriteearlyhintslinks.

We need to provide a compatible layer for node@14 and node@16.
Patching to use additionalHeaders and .socket are needed.

And, if the native one is available, for example node@18.11.0. We should absolutely go into that.

[jsumners]

Also we expect that fastify is behind a reverse proxy like Ingress/traefik which resolves a http2 request to http1.1 and vice versa.

That's not necessarily true. A reverse proxy can still use http/2 to communicate to the backend services.

Maybe we can transplant http2 from nodejs sourcecode to our plugin?

That would be a maintenance nightmare.

[climba03003]

That would be a maintenance nightmare.

Not really re-invented the wheel, http2 already provide a method called additionalHeaders. We can directly pass the header with additional :status.

[Uzlopak]

My assessment:

• modify formatEntry to not add "Link:" when http2
• concat the early hints into message not with CRLF but with a comma, no trailing comma
• use additionalHeaders instead of write on reply.raw

I am wondering how we can test http2 because undici does not support http2

[climba03003]

I am wondering how we can test http2 because undici does not support http2

Use built-in net or http2 package.

[Uzlopak]

created #8 for discussing http2 implementation

[lilouartz]

Looks like the PR was closed without resolution :-(

[climba03003]

Looks like the PR was closed without resolution :-(

Since, Node.js already implemented the writeEarlyHints in both http and http2.
You should use the native function instead of relying this project (unless you are in old Node.js version).

[lilouartz]

ah, would be useful to document this somewhere.

[mcollina]

fastify/fastify#5479