envoyproxy/envoy

ext_authz to be able to set x-envoy-force-trace

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#21,670 opened on Jun 12, 2022

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area/ext_authzhelp wanted

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Description

Title: ext_authz to be able to set x-envoy-force-trace

Description:

The documentation states that

If an internal request sets this header, Envoy will modify the generated x-request-id such that it forces traces to be collected.

However, setting this in an ext_authz with allowed_upstream_headers doesn't enable tracing. It does cause an x-request-id response header.

It would be practical if ext_authz could set the tracing state based on user/session configuration since it's already manipulating that data anyway.

Relevant Links:

The code that checks the header is in conn_manager_utility.cc, but I wonder if this condition in conn_manager_impl.cc is what's causing this decision to be re-evaluated after ext_authz.

The x-request-id response header decision doesn't check the trace reason, but explicitly looks at the force header, which explains why that shows up even without tracing.

Contributor guide

Research direction
Investigate the code paths in conn manager utility.cc and conn manager impl.cc to understand where x envoy force trace is checked and how ext authz can influence it. Determine the minimal changes needed to allow ext authz to set the header and affect tracing state.
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.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
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
C++Envoy basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65