micrometer-metrics/micrometer

Cache metrics for http clients

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#1,700 opened on Nov 11, 2019

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enhancementhelp wantedwaiting for feedback

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Description

Both httpclient from Apache and OkHttp (which are instrumented by micrometer: OkHttpMetricsEventListener and https://github.com/micrometer-metrics/micrometer/issues/533) support provider driven caching (based on http headers)

It would be helpful (for the sake of completeness) for micrometer to provide insight to the state of caches (size, maxSize, hit and misses).

I've drafted a cache metrics for OkHttp which I'd like to get feedback ok: https://github.com/micrometer-metrics/micrometer/compare/master...kubamarchwicki:httpclient-cache-metrics. If that's something interesting, I'd hapilly finalize both OkHttp as well as httpclient.

Contributor guide

Research direction
Examine the existing OkHttpMetricsEventListener and Apache HttpClient instrumentation to understand how to hook into cache events (size, maxSize, hits, misses) and register appropriate Micrometer meters (Gauge, Counter). Refer to the draft PR mentioned.
Tech stack
java
Domain
observability
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
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.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
JavaMicrometer
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30