linkerd / linkerd/linkerd

Expose service 2 service call stats

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#2,137 2 comments 0 reactions 0 assignees View on GitHub

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Dominant language
Scala
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Description

- [x] Feature request

Expose stats scoped by the caller service, so linkerd can be used as the source of truth for all service to service call metrics.
Considering this can explode easily, it is probably better so expose only a limited numbers of stats.

For each route i would suggest to expose the same metrics exposed by https://github.com/twitter/finagle/blob/master/finagle-http/src/main/scala/com/twitter/finagle/http/filter/StatsFilter.scala

- `status/`
A counter of the number of responses received, or returned for servers, that had this statusCode.
- `status/`
Same as status/statusCode but aggregated per category, e.g. all 500 range responses count as 5XX for this counter.
- `time/`
A histogram on duration in milliseconds per HTTP status code.
- `time/`
A histogram on duration in milliseconds per HTTP status code category.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Review the Linkerd 1.x repository and compare its existing route statistics with Finagle's StatsFilter.scala, which the issue references. Define how caller-scoped metrics would be limited without unbounded cardinality, then verify that status counters and time histograms are exposed for HTTP status codes and categories.

Written by the indexing model from the issue text.

Assessment

Tech stack
scala
Domain
observability
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
25/100

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