refactor(contrib/envoy): implement message_processor for logic re-use by e-n-0 · Pull Request #3860 · DataDog/dd-trace-go

e-n-0 · 2025-08-08T15:07:34Z

What does this PR do?

This PR refactor how the envoy contrib is handling messages. Now the processing of analysis messages (request headers, request body, response headers, response body) is now implemented agnostic to the framework its instrumenting. This is implemented in the package message_processor.

Motivation

The motivation to create a new package message_processor is the ability to re-use the message processing logic as an external processor. This package will be used in part of #3912 that implement the support of messages processing for HAProxy.

The package message_processor is implemented inside the envoy contrib to keep the agility of deploying releases out of the normal releases process of the tracer (using the -docker.x tag).

Reviewer's Checklist

Changed code has unit tests for its functionality at or near 100% coverage.
System-Tests covering this feature have been added and enabled with the va.b.c-dev version tag.
There is a benchmark for any new code, or changes to existing code.
If this interacts with the agent in a new way, a system test has been added.
New code is free of linting errors. You can check this by running ./scripts/lint.sh locally.
Add an appropriate team label so this PR gets put in the right place for the release notes.
Non-trivial go.mod changes, e.g. adding new modules, are reviewed by @DataDog/dd-trace-go-guild.

Unsure? Have a question? Request a review!

pr-commenter · 2025-08-08T15:14:07Z

Benchmarks

Benchmark execution time: 2025-08-25 13:41:13

Comparing candidate commit 6db4230 in PR branch flavien/envoy/refactor-separation with baseline commit b5536ad in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 24 metrics, 0 unstable metrics.

datadog-datadog-prod-us1 · 2025-08-25T13:19:10Z

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

_{This comment will be updated automatically if new data arrives.

🔗 Commit SHA: 6db4230 | Docs | Was this helpful? Give us feedback!}

…ment needed interfaces to work with the mp

… (pointers)

eliottness · 2025-09-01T11:26:53Z

 	"sync/atomic"
 	"time"

+	"github.com/DataDog/dd-trace-go/contrib/envoyproxy/go-control-plane/v2/message_processor"


Actually underscores in package names are banned by the geneva convention. Something like msgproc should be enough. Usually I encourage longer names but with package names this create a bunch of wierd issues so no

eliottness · 2025-09-01T11:27:57Z

 		}

+		// Handle the action returned by the message processor
+		processingResponse, err := s.handleAction(action, &processingRequest)


Do you really need a pointer to the processing request here or a copy would be fine?

eliottness · 2025-09-01T11:32:46Z

 		var (
-			response *envoyextproc.ProcessingResponse
+			action   message_processor.Action
 			err      error
+			reqState *message_processor.RequestState
 		)
-		response, *currentRequest, err = s.messageProcessor.ProcessRequestHeaders(ctx, v)
-		return response, err
+		reqState, action, err = s.messageProcessor.OnRequestHeaders(ctx, &requestHeadersEnvoy{v, s.config.Integration})
+		if err == nil {
+			*currentRequest = *reqState
+		}


Suggested change

var (

response *envoyextproc.ProcessingResponse

action message_processor.Action

err error

reqState *message_processor.RequestState

)

response, *currentRequest, err = s.messageProcessor.ProcessRequestHeaders(ctx, v)

return response, err

reqState, action, err = s.messageProcessor.OnRequestHeaders(ctx, &requestHeadersEnvoy{v, s.config.Integration})

if err == nil {

*currentRequest = *reqState

}

var (

action message_processor.Action

err error

)

*currentRequest , action, err = s.messageProcessor.OnRequestHeaders(ctx, &requestHeadersEnvoy{v, s.config.Integration})

eliottness · 2025-09-01T11:37:41Z

+func (a *requestHeadersEnvoy) EndOfStream() bool {
+	return a.req.RequestHeaders.GetEndOfStream()
+}


This kind of boilerplate can be avoided by using embedding on the right object

eliottness · 2025-09-01T11:38:35Z

+func (a *requestBodyEnvoy) Body() []byte {
+	return a.req.RequestBody.GetBody()
+}
+
+func (a *requestBodyEnvoy) EndOfStream() bool {
+	return a.req.RequestBody.GetEndOfStream()
+}


Same here about embedding

eliottness · 2025-09-01T11:57:40Z

+	headerMutation, err := reqState.PropagationHeaders()
+	if err != nil {
+		reqState.Close()
+		return nil, Action{}, err


Same for the action{}

eliottness · 2025-09-01T11:58:18Z

+	if !req.EndOfStream() && mp.isBodySupported(httpReq.Header.Get("Content-Type"), mp.config) {
+		requestBody = true
+		reqState.AwaitingRequestBody = true
+		// Todo: Set telemetry body size (using content-length)


Can't we do it here ?

eliottness · 2025-09-01T11:59:18Z

+	if mp.config.BodyParsingSizeLimit <= 0 || !reqState.AwaitingRequestBody {
+		mp.instr.Logger().Error("message_processor: the body parsing has been wrongly configured. " +
+			"Please refer to the official documentation for guidance on the proper settings or contact support.")
+		return newContinueAction(), nil


what do you mean by wrongly configured. I don't see how it could be actionable for a user.

eliottness · 2025-09-01T13:19:12Z

I am trying to understand why the types and funcs in this file are here if the interfaces from this package are delegating this job

eliottness · 2025-09-01T14:57:51Z

 		}

-		if currentRequest.Blocked {
+		if _, ok := processingResponse.Response.(*envoyextproc.ProcessingResponse_ImmediateResponse); ok {


wasn't the ActionType made for this kind of cases ?

e-n-0 · 2025-09-12T11:51:20Z

supersed by #3945

github-actions Bot added the apm:ecosystem contrib/* related feature requests or bugs label Aug 8, 2025

e-n-0 force-pushed the flavien/envoy/refactor-separation branch from 062d617 to fa1be8a Compare August 8, 2025 15:08

e-n-0 changed the title ~~contrib/envoy: implement a message_processor~~ contrib/envoy: implement a message_processor to reuse logic Aug 8, 2025

e-n-0 force-pushed the flavien/envoy/refactor-separation branch 2 times, most recently from 048876a to 049d56e Compare August 25, 2025 13:07

e-n-0 marked this pull request as ready for review August 25, 2025 13:27

e-n-0 requested a review from a team as a code owner August 25, 2025 13:27

e-n-0 added 4 commits August 25, 2025 15:28

Implement message_processor and refactor Envoy specific code to imple…

0db1bb0

…ment needed interfaces to work with the mp

refine

695e475

revert changes on main.go (unwanted dev mode)

1940e53

fix for headers responses data (+directions) + haproxy needed changes…

6db4230

… (pointers)

e-n-0 force-pushed the flavien/envoy/refactor-separation branch from 9483abb to 6db4230 Compare August 25, 2025 13:28

e-n-0 marked this pull request as draft August 25, 2025 13:39

e-n-0 changed the title ~~contrib/envoy: implement a message_processor to reuse logic~~ refactor(contrib/envoy): implement message_processor for logic re-use Aug 25, 2025

e-n-0 marked this pull request as ready for review August 26, 2025 13:13

e-n-0 mentioned this pull request Aug 26, 2025

feat(contrib/haproxy): HAProxy AAP support #3912

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eliottness requested changes Sep 1, 2025

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e-n-0 closed this Sep 12, 2025

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What does this PR do?

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e-n-0 commented Sep 12, 2025

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e-n-0 commented Aug 8, 2025 •

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