envoyproxy/envoy

Accessing request headers in envoy_on_response (lua HTTP filter).

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#4,613 opened on Oct 5, 2018

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Description

I'm trying to use a lua HTTP filter to set a response header whose value depends on a request header.

As a simple example, suppose we want to copy a header from the request to the response. How can we do this using a lua filter?

Maybe we can store the request header in a "global" table during envoy_on_request and read it later when envoy_on_response is called. However, even if this approach makes sense, how can we correlate responses with requests to be able to do this?

Contributor guide

Research direction
Review the Envoy Lua filter documentation and examine how request headers can be stored in a table during envoy on request and accessed in envoy on response. Consider using dynamic metadata or stream info to correlate requests and responses.
Tech stack
cpplua
Domain
api
Issue type
Research
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.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Git
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65