feat: add RequestReply control plane

[Cali0707]

This adds the Request Reply control plane (as a first pass). In follow ups, TLS/authn/authz/observability/AES key rotation will be handled.

This depends on:

• Update request reply types #8698
• feat: add complete request reply data plane #8699
• feat: enable KN_VERIFY_CORRELATION_ID in cesql runtimes #8700

Proposed Changes

• Add controller and reconciler for the Request

feat: the RequestReply resource can now be deployed from eventing core

[Cali0707]

/cc @creydr @matzew

I'll add unit tests to this today, but besides that this is ready for review

[Cali0707]

The broken builds/tests are coming from #8698 not being in yet - they should work once it is in

[Cali0707]

/hold

[Cali0707]

For testing (with the dependent PRs merged), I did:

1. Create a knative function with the following handle func:

func Handle(ctx context.Context, e event.Event) (*event.Event, error) {
	/*
	 * YOUR CODE HERE
	 *
	 * Try running `go test`.  Add more test as you code in `handle_test.go`.
	 */

	fmt.Println("Received event")
	fmt.Println(e) // echo to local output
	correlationId, ok := e.Extensions()["correlationid"]
	if !ok {
		fmt.Println("warning: failed to extract correlation id from event, reply may not be routed properly")
	} else {
		delete(e.Extensions(), "correlationid")
		e.SetExtension("replyid", correlationId)
	}
	return &e, nil // echo to caller
}

2. Deploy the following yaml resources:

apiVersion: eventing.knative.dev/v1
kind: Broker
metadata:
  name: example
---
apiVersion: eventing.knative.dev/v1
kind: Trigger
metadata:
  name: example
spec:
  broker: example
  subscriber:
    ref:
      apiVersion: serving.knative.dev/v1
      kind: Service
      name: echo-reply
  filters:
    - cesql: "EXISTS correlationid AND NOT EXISTS replyid"
---
apiVersion: eventing.knative.dev/v1alpha1
kind: RequestReply
metadata:
  name: rr-test
spec:
  brokerRef:
    name: example
    kind: Broker
    apiVersion: eventing.knative.dev/v1

Curl the request reply url within the cluster:

kubectl run curl --image=docker.io/curlimages/curl --rm=true --restart=Never -ti \
-- -X POST -v \
-H "content-type: application/json" \
-H "ce-specversion: 1.0" \
-H "ce-source: my/curl/command" \
-H "ce-type: my.demo.event" \
-H "ce-id: 6cf17c7b-30b1-45a6-80b0-4cf58c92b947" \
-d '{"name":"Request Reply demo"}' \
http://request-reply.knative-eventing.svc.cluster.local/default/rr-test
If you don't see a command prompt, try pressing enter.
< HTTP/1.1 200 OK
< Allow: POST, OPTIONS
< Ce-Correlationid: 6cf17c7b-30b1-45a6-80b0-4cf58c92b947:N3RDobCYCVeP73fuzrXg1x4tYE2c3VkFAMqRADCM1uISFeKTvpKoN7L9YSrRMTvOKcbtQk1CGzvq5L3HEheAfw==:0
< Ce-Id: 6cf17c7b-30b1-45a6-80b0-4cf58c92b947
< Ce-Knativearrivaltime: 2025-09-02T21:38:07.133319085Z
< Ce-Replyid: 6cf17c7b-30b1-45a6-80b0-4cf58c92b947:N3RDobCYCVeP73fuzrXg1x4tYE2c3VkFAMqRADCM1uISFeKTvpKoN7L9YSrRMTvOKcbtQk1CGzvq5L3HEheAfw==:0
< Ce-Source: my/curl/command
< Ce-Specversion: 1.0
< Ce-Type: my.demo.event
< Content-Length: 29
< Content-Type: application/json
< Date: Tue, 02 Sep 2025 21:38:07 GMT
< 
* Connection #0 to host request-reply.knative-eventing.svc.cluster.local left intact
{"name":"Request Reply demo"}pod "curl" deleted

[matzew]

can we have a test for the reconciler?

[matzew]

@Cali0707 Mind sharing the old feature track document for that ?

[Cali0707]

@Cali0707 Mind sharing the old feature track document for that ?

Yeah - it is here https://docs.google.com/document/d/1vrCfIH9wRrsl8j7XpHK5XiVRgnx5nB4mLHsp0AxU_0Y/edit?usp=sharing @matzew

[Cali0707]

/cc @matzew

[codecov]

Codecov Report

❌ Patch coverage is 27.12215% with 352 lines in your changes missing coverage. Please review.
✅ Project coverage is 50.19%. Comparing base (e804605) to head (c072edc).
⚠️ Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/reconciler/requestreply/requestreply.go	53.90%	92 Missing and 20 partials ⚠️
pkg/reconciler/requestreply/controller.go	0.00%	61 Missing ⚠️
pkg/reconciler/testing/v1/statefulset.go	0.00%	58 Missing ⚠️
pkg/reconciler/testing/v1/pod.go	0.00%	52 Missing ⚠️
pkg/reconciler/testing/v1alpha1/requestreply.go	0.00%	50 Missing ⚠️
pkg/reconciler/testing/v1/trigger.go	0.00%	11 Missing ⚠️
cmd/controller/main.go	0.00%	4 Missing ⚠️
pkg/reconciler/testing/v1/listers.go	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8701      +/-   ##
==========================================
- Coverage   51.58%   50.19%   -1.40%     
==========================================
  Files         401      409       +8     
  Lines       25446    26659    +1213     
==========================================
+ Hits        13126    13381     +255     
- Misses      11518    12436     +918     
- Partials      802      842      +40     

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[Cali0707]

/unhold
/cc @creydr

[creydr]

Thanks @Cali0707
I tested it as (after rebased this PR) and it worked 🎉

Maybe we can add e2e tests for it as well (as a separate PR) and create issues to add TLS and auth support

/lgtm

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Cali0707, creydr

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