akka/akka-http

Monitoring http client retries

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#1,543 opened on Nov 21, 2017

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 (2 comments) (0 reactions) (0 assignees)Scala (1,311 stars) (598 forks)batch import
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Description

We have a use case where we need to know the exact number of requests that we send to the services downstream (due to quota/contractual obligations).

We hoped to leverage akka-http retry mechanism for that (those are all GET requests), however my research shows that there seems to be no way to get retry information at the client level.

Here we still have access to the retriesLeft field of the RequestContext, however it is not propagated to the response that is exposed to the client. I'm not really sure whether there is a solution without a breaking change in the interface, but it's definitely a useful feature to have.

The workaround is to roll my own retries instead.

Contributor guide

Tech stack
scala
Domain
apiobservability
Issue type
feature
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.
half day
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.
mostly clear
Prerequisites
Scalaakka http internals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
The issue requests propagating the `retriesLeft` field from `RequestContext` to the client response. The relevant code is in `PoolInterfaceActor.scala` at line 121 (see issue). Investigate how to expose retry count without breaking the public API. Consider adding a header or callback. Check existing comments for alternative approaches.