[feature] serve admin interface via http2

[rauanmayemir]

Is your feature request related to a problem? Please describe.

Admin interface (and api in general) is currently served via HTTP1.1.

Describe the solution you'd like.

What would the feature look like? How would it work? How would it change the API?

It would be nice to have api serve HTTP2 as well (as H2C). (I've seen that you already optionally support QUIC/HTTP3, so H2C/HTTP2 would be even simpler as it's just a wrapper over mux.

...

[FZambia]

Hello, Centrifugo already supports HTTP/2 out of the box.

You need to configure TLS to make it work. For example, with mkcert tool:

❯ mkcert localhost 127.0.0.1 ::1

Created a new certificate valid for the following names 📜
 - "localhost"
 - "127.0.0.1"
 - "::1"

The certificate is at "./localhost+2.pem" and the key at "./localhost+2-key.pem" ✅

Run Centrifugo with TLS:

./centrifugo --tls --tls_cert localhost+2.pem --tls_key localhost+2-key.pem --api_insecure

Note, api_insecure is only to simplify example here.

Then check API response:

curl -X POST "https://localhost:8000/api/info" --data '{}'  -v

You will see HTTP/2 headers:

*  SSL certificate verify ok.
* using HTTP/2
* h2 [:method: POST]
* h2 [:scheme: https]
* h2 [:authority: localhost:8000]
* h2 [:path: /api/info]
* h2 [user-agent: curl/8.1.2]
* h2 [accept: */*]
* h2 [content-length: 2]
* h2 [content-type: application/x-www-form-urlencoded]
* Using Stream ID: 1 (easy handle 0x13f80c600)
> POST /api/info HTTP/2
> Host: localhost:8000
> User-Agent: curl/8.1.2
> Accept: */*
> Content-Length: 2
> Content-Type: application/x-www-form-urlencoded
>
* We are completely uploaded and fine
< HTTP/2 200
< content-type: application/json
< date: Mon, 11 Mar 2024 16:00:49 GMT

Then check admin UI:

See also: https://centrifugal.dev/docs/faq#does-centrifugo-work-with-http2

Having said this all, I don't see the problem with HTTP 1.1, I doubt about significant practical benefits here. So supporting H2C should be justified by a practical reason.

[rauanmayemir]

It’s not about a benefit, but rather a limitation I had and wanted to avoid putting it behind proxy.

[FZambia]

Could you please explain what kind of limitation? Does the above description solves it for you?

[rauanmayemir]

@FZambia The description above is for serving TLS, it doesn't cover H2C. The limitation is technical and I don't have a reasonable justification, so I'll leave this as 'nice to have'.