envoyproxy/envoy

Early Hints support

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#25,881 opened on Mar 2, 2023

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area/httphelp wantedinvestigate

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Description

Title: Is Early Hints supported?

Description:

With Early Hints you can send multiple 103 responses to the client:

HTTP/1.1 103 Early Hints
Link: </main.css>; rel=preload; as=style

HTTP/1.1 103 Early Hints
Link: </style.css>; rel=preload; as=style
Link: </script.js>; rel=preload; as=script

HTTP/1.1 200 OK
Date: Fri, 26 May 2017 10:02:11 GMT
Content-Length: 1234
Content-Type: text/html; charset=utf-8
Link: </main.css>; rel=preload; as=style
Link: </newstyle.css>; rel=preload; as=style
Link: </script.js>; rel=preload; as=script

Looks like that 103 headers is ignored, and response proxied only after 200 status. Maybe this filter responsible for this behaviour - https://github.com/envoyproxy/envoy/blob/main/contrib/golang/filters/http/source/go/pkg/api/type.go#L38 (don't sure this code are relates to problem)

Relevant Links

Early Hints specification - https://httpwg.org/specs/rfc8297.html#early-hints

Contributor guide

Research direction
Investigate how Envoy handles 1xx responses and implement support for 103 Early Hints, ensuring multiple 103 responses can be sent before the final response, and updating the HTTP filter API if necessary.
Tech stack
None
Domain
backendinfrastructure
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
HTTPC++
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20