feat: make cluster domain configurable in KEDA deployer

[Itx-Psycho0]

Problem

The external name service to the keda-add-ons-http-interceptor-proxy was hardcoded with the cluster domain set to cluster.local. This works for most cases, but fails in clusters with custom domain configurations.

Solution

Made the cluster domain configurable by adding a ClusterDomain field to the DeploySpec struct. The KEDA deployer now uses this field to build the interceptor proxy service URL, with cluster.local as the default fallback for backward compatibility.

Changes

• Added ClusterDomain field to DeploySpec in pkg/functions/function.go
• Updated interceptorBridgeService() in pkg/keda/deployer.go to use the configurable cluster domain
• Added unit tests in pkg/keda/deployer_test.go to verify the functionality

Usage

Users can now configure the cluster domain in their func.yaml:

deploy:
  deployer: keda
  clusterDomain: "custom.domain"  # Optional, defaults to "cluster.local"

Testing
✅ All unit tests pass
✅ Linting checks pass
✅ Backward compatible (defaults to "cluster.local")
Fixes #3403

[knative-prow]

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[knative-prow]

Hi @Itx-Psycho0. Thanks for your PR.

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[Itx-Psycho0]

Hi maintainers,

I've implemented a fix for issue #3403 that makes the cluster domain configurable in the KEDA deployer.

Summary:

• Added a ClusterDomain field to DeploySpec that allows users to configure the cluster domain
• Updated the KEDA deployer to use this field when building the interceptor proxy service URL
• Defaults to "cluster.local" for backward compatibility
• Added comprehensive unit tests

The implementation is backward compatible and follows the existing patterns in the codebase. All tests pass and linting is clean.

I'd appreciate your review when you have a chance.

@lkingland @creydr @matejvasek

Thanks!

[matejvasek]

Is this only keda specific?

[matejvasek]

@creydr please look at this.

[matejvasek]

Isn't cluster domain setting of a cluster, not a function?

[gauron99]

Is this only keda specific?

wouldnt this also touch on raw k8s deployer?

[Itx-Psycho0]

You're absolutely right on all points. Let me address the concerns:

"Is this only KEDA specific?"
No, it's not. The cluster domain affects any deployer that builds internal service URLs. The raw K8s deployer likely has similar hardcoded references to cluster.local.

"Isn't cluster domain setting of a cluster, not a function?"
You're correct, the cluster domain is a cluster-level configuration, not a function-level one. Putting it in DeploySpec (per-function) is architecturally wrong.

Proposed Better Solution - Auto-detect cluster domain from the cluster's DNS configuration
Make it a global/cluster-level config (not per-function)
Apply to all deployers (KEDA, raw K8s, Knative if needed)

Implementation approach:
Add cluster domain detection in the deployer initialization
Fall back to "cluster.local" if detection fails
Allow override via global config (not per-function)
Apply consistently across all deployers

Should I rework the PR with this approach? I can:
Move cluster domain to a global config
Add auto-detection logic
Apply it to both KEDA and raw K8s deployers
Add tests for all deployers

Let me know if this direction makes sense!
@gauron99 @matejvasek