envoyproxy/envoy

Send custom key-value pairs in ot-span-context to Zipkin

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#2,031 opened on Nov 9, 2017

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 (3 comments) (1 reaction) (0 assignees)C++ (5,373 forks)batch import
area/tracingenhancementhelp wanted

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Description

Thanks for maintaining the great project 👍

Envoy does seem to propagate ot-span-context but drops most of the key-values included in it before sending it to Zipkin.

Would it be possible to send those key-values as binary annotations of Zipkin spans? Could I contribute it?

Context:

  • After looking into code, it turns out that Envoy as of today drops all the keys in ot-span-context other than a few, well-known keys like traceid and spanid, before sending these to Zipkin.
  • AFAIK, ot-span-context could be populated with "custom" keys and values other than these, e.g. by our apps, to provide additional context throughout multiple spans in single trace.
  • If Envoy could translate those to corresponding binary annotations in Zipkin spans, we could view those custom key-value pairs from ot-span-context in Zipkin.
  • FYI, an app like dd-zipkin-proxy allows Datadog to consume Zipkin spans containing arbitrary binary annotations so that it would also help Datadog users.

Contributor guide

Research direction
Inspect the source code at source/common/tracing/zipkin/tracer.cc, specifically lines 53-114, to understand how ot span context is parsed and how Zipkin spans are created. Identify where custom key value pairs could be added as binary annotations. Then implement the necessary changes to propagate those pairs.
Tech stack
cpp
Domain
observabilitybackend
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 codebase understandingZipkin tracing
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
45