Emit an HTTP request-duration histogram metric from src/middleware/access-log.ts

[Jagadeeshftw]

Description

src/middleware/access-log.ts records method, path, status, and duration as a structured log line per request (via redactSensitiveParams and res.finish), but that duration is only ever visible by grepping logs — there is no aggregate, queryable latency distribution. Once a metrics registry exists, emit the same per-request duration as a labeled histogram (method, route, status class) so p50/p95/p99 latency can be graphed directly.

Requirements and context

• Add a http_request_duration_seconds histogram recorded from the existing res.finish handler in src/middleware/access-log.ts, reusing the duration already computed for the log line rather than measuring twice
• Label by normalized route (not raw path, to avoid unbounded cardinality from path params) and status code class (2xx/4xx/5xx)
• Keep the existing structured log line and PII redaction behavior completely unchanged
• Must be secure, tested, and documented
• Should be efficient and easy to review

Suggested execution

Fork the repo and create a branch

git checkout -b feature/access-log-duration-metric

Implement changes

• Update/Write: src/middleware/access-log.ts
• Add/Update tests: src/middleware/access-log.test.ts
• Add documentation: docs/middleware/access-log.md
• Include clear code comments and TS types
• Validate security assumptions

Test and commit

• Run tests: pnpm test
• Cover edge cases
• Include test output and security notes

Example commit message

feat: emit request-duration histogram from access log

Guidelines

• Minimum 95 percent test coverage
• Clear documentation
• Timeframe: 96 hours

[Stephan-Thomas]

📋 Grainlify Application

@Stephan-Thomas has applied to work on this issue as part of the Grainlify program.

hi, i would like to work on this.

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[TS-mfon]

📋 Grainlify Application

@TS-mfon has applied to work on this issue as part of the Grainlify program.

GM

i'm a blockchain developer

please can i work on this issue

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[dotmantissa]

📋 Grainlify Application

@dotmantissa has applied to work on this issue as part of the Grainlify program.

Hi maintainers,

I'd like to work on this. I'll add the http_request_duration_seconds histogram to the existing res.finish handler in access-log.ts, reusing the already computed duration, label by normalized route and status class to avoid cardinality issues, leave the structured log line and PII redaction completely untouched, and document it in docs/middleware/access-log.md with 95 percent test coverage.

I estimate I can have a PR ready within 3 hours of being assigned. Could you please assign this to me?

Thanks.

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Repo Maintainers: To accept this application, review their application or assign @dotmantissa to this issue.

[Delightech28]

I'd like to work on this