akka/akka-http

Configuration options could use clarification on dependencies between them.

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#1,009 opened on Apr 1, 2017

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Description

Config options around sizing are a bit confusing right now.

Consider setting up 2 Akka-Http services, A and B, where A makes requests to B for streaming data, say a 20MB file.

Which options would you set?

Akka-Http Client on service A defaults to 4 connections, Akka-Http Server on service B defaults to serving 1024 connections.

You will run into a runtime error if testing with a 5MB file you will be surprised at runtime to find out that a 10MB file will not work due to Max-Content-Length.

What settings will you need to make sure this does not fail with chunk size incorrect errors? What if someone sets the chunk size different on each service?

max-content-length? decode-max-bytes-per-chunk? max-chunk-size?

Which of these are dependent upon which and will break if they are set to incompatible settings?

Do they need to be set in: akka.http.client? akka.http.server? akka.http.pool? akka.http.pool.client? akka.http.parsing? akka.http.client.parsing? akka.http.host-connection-pool.client.parsing?

If you set one and miss another will the service fail at runtime due to incompatible sizes or will it adjust/re-chunk dynamically?

Is there a best practice advice to verify all of these settings are correct and compatible? For example always test with a file at least 2x the size of akka.http.foo.setting?

Contributor guide

Tech stack
None
Domain
backend
Issue type
documentation
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.
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.
clear
Prerequisites
Akka Http configurationHTTP streaming concepts
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50
Research direction
Investigate the Akka Http configuration reference (e.g., reference.conf) to understand the dependencies between max content length, decode max bytes per chunk, and max chunk size. Review how these settings interact across client, server, pool, and parsing scopes. Check existing documentation and any related issues for guidance. The goal is to produce a clear explanation and possibly update the docs with a best practices section.