envoyproxy/envoy

wasm: metrics never expire and accumulate

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#14,070 opened on Nov 17, 2020

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area/statsarea/wasmbughelp wanted

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Description

Wasm filter implements the stats by allocating Envoy stats in the context and never de-allocating them. Since ABI encourages dynamic values, the stats accumulate and eventually leak (also, potentially exposing a security risk if stat values are untrusted).

Contributor guide

Research direction
Investigate the Wasm filter implementation in the Envoy source code (likely under source/extensions/filters/http/wasm/). Understand how Envoy stats are currently allocated via the ABI and why they never expire. Review the discussion in issue #14070 for proposed solutions and maintainer feedback. Consider implementing a mechanism to track and deallocate stats when the Wasm module is destroyed or through periodic cleanup.
Tech stack
cppwasm
Domain
backendperformancesecurityobservability
Issue type
Bug
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.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Envoy proxy basicsWebAssembly modulesEnvoy stat subsystem
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25