envoyproxy/envoy

proposal: design Wasm ABI for tracing providers

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#10,563 opened on Mar 28, 2020

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area/wasmdesign proposalhelp wanted

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Description

Title: design Wasm ABI for tracers

Context:

  • after Envoy moved to libc++, dynamic_ot-based tracers got broken because they were relying on C++ ABI
  • following that, a potential new tracing provider expressed its interest in C ABI instead
  • so, it seems that tracing providers could benefit from having their own Wasm ABI

Proposal:

  • Let's try to design Wasm ABI for tracers
  • Along the way, let's expand on ideas that came out of reviews for Wasm upstreaming PRs, namely:
    • ABI should be modular and complementary to proxy-wasm/spec
    • ABI should use versioning scheme similar to regular Envoy extensions, e.g. envoy.tracers.v1alpha0
    • ABI should support usage model consistent with regular Envoy extensions, e.g. it should be possible to have N instances of the same extension type each with a different configuration
    • ABI should be optimized for data passing from Envoy to the Wasm extension in just 1 function call

Contributor guide

Research direction
Review the proxy wasm specification and current Envoy tracing provider implementations. Propose a modular ABI design that complements the existing spec, using versioning similar to Envoy extensions, and optimize data passing for single function call.
Tech stack
wasm
Domain
observability
Issue type
Research
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Over 1 week
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
WasmEnvoy
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25