envoyproxy/envoy

API request: xds async NACK

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#9,447 opened on Dec 21, 2019

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area/xdsenhancementhelp wanted

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Description

When envoy receives a listener from management server it has 3 choices

  1. accept listener and put it in ready state
  2. Reject listener with a NACK
  3. Accept config and put listener in a warming state awaiting an async operation.

If the async operation fails for any reason and it was performed against separate management server, the original management server has no way to know what happened.

There should be a way to indicate a NACK after async operations complete.

This happens with SDS, Wasm code fetch via url or fcds.

Related issues: https://github.com/envoyproxy/envoy/issues/5739 https://github.com/envoyproxy/envoy/issues/7867

Contributor guide

Research direction
Examine the xDS protocol and the current NACK implementation in Envoy. Understand how async operations like SDS, Wasm fetch, or FCDS work. Then design a way to send a NACK after async completion, possibly by extending the xDS response or introducing a new message. Review related issues #5739 and #7867 for context.
Tech stack
cpp
Domain
backend
Issue type
Feature
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.
3-5 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.
Mostly clear
Prerequisites
C++envoy internals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25