✨(feat): add necessary changes to support applyconfiguration gen #5237

yyewolf · 2025-11-19T19:47:51Z

I'm not sure why this issue has been closed: #3692
But I haven't seen anyone working on this.

I marked the PR as breaking though I am not sure of the semantics, since I renamed GroupVersion to SchemeGroupVersion I feel like this is a breaking change to the generated code, even though it's not a breaking change to the CLI.

I'm also working on modifying the Makefile and E2E tests which is gonna be in another PR.

linux-foundation-easycla · 2025-11-19T19:47:57Z

The committers listed above are authorized under a signed CLA.

✅ login: yyewolf / name: Tristan Smagghe (473f3ca, 7166a19, 8d51a9f, c91bfa9)

k8s-ci-robot · 2025-11-19T19:47:58Z

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k8s-ci-robot · 2025-11-19T19:48:00Z

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k8s-ci-robot · 2025-11-19T19:48:01Z

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camilamacedo86 · 2025-11-19T20:02:36Z

pkg/plugins/golang/v4/scaffolds/internal/templates/api/doc.go

@@ -0,0 +1,59 @@
+/*


Thank you for looking into that. 🎉

If it turns out to be a breaking change, we need to find a way to make it backwards compatible. We can’t introduce it right now.

However, if you want to go ahead and implement the changes based on how you think it should work, and then share your findings with us, we can refine it together in a follow-up.

Because of that, I wouldn’t worry about the e2e tests at this stage. Instead, focus on making the changes in a way that, when you run make generate, the testdata samples are regenerated—or at least show how a project would look with the new behavior.

camilamacedo86 · 2025-11-19T20:03:07Z

pkg/plugins/golang/v4/scaffolds/internal/templates/api/group.go

-	// GroupVersion is group version used to register these objects.
-	GroupVersion = schema.GroupVersion{Group: "{{ .Resource.QualifiedGroup }}", Version: "{{ .Resource.Version }}"}
+	// SchemeGroupVersion is group version used to register these objects.
+	SchemeGroupVersion = schema.GroupVersion{Group: "{{ .Resource.QualifiedGroup }}", Version: "{{ .Resource.Version }}"}


Why would those changes?
We did not change the values. Why would we need to change the exported variable name?

The generated code for applyconfiguration uses this variable name, it's referenced here: https://github.com/kubernetes/code-generator/blob/master/cmd/applyconfiguration-gen/generators/util.go#L129

However in order to make it backward compatible, we can easily go back and do

Suggested change

SchemeGroupVersion = schema.GroupVersion{Group: "{{ .Resource.QualifiedGroup }}", Version: "{{ .Resource.Version }}"}

GroupVersion = schema.GroupVersion{Group: "{{ .Resource.QualifiedGroup }}", Version: "{{ .Resource.Version }}"}

SchemeGroupVersion = GroupVersion

camilamacedo86 · 2025-11-19T20:05:09Z

pkg/plugins/golang/v4/scaffolds/internal/templates/api/types.go

 //nolint:lll
 const typesTemplate = `{{ .Boilerplate }}

+// +kubebuilder:ac:generate=true


I think the feature must be optional.
We should not promote it by default, right?
By default, people should still be working as they do today.

You're right, I'll make it optional

But if you want to add it in a way that we can first see it working, then we can evaluate it.

Do you have a project that uses this configuration? I’ve never tried to use it myself, so looking at an example would be helpful and could give us some ideas on how we might add it.

I don't have a project that uses this configuration, however I ran the generate testdata using it: 537f54e

I added the flag, made it true by default (for now so we can see the generated code) and also generated the code 👍

camilamacedo86 · 2025-11-19T20:06:09Z

pkg/plugins/golang/v4/scaffolds/internal/templates/api/types.go

 {{- else if not .Resource.IsRegularPlural }}
 // +kubebuilder:resource:path={{ .Resource.Plural }}
+{{- else }}
+// +kubebuilder:resource


What does this marker do?
Have you an example of a project using the option for we give a look?
Could you share?

controller-tools uses this marker to mark the type as a resource type:

Marker: https://github.com/kubernetes-sigs/controller-tools/blob/main/pkg/applyconfiguration/gen.go#L45C1-L45C127
Help message associated: https://github.com/kubernetes-sigs/controller-tools/blob/main/pkg/applyconfiguration/gen.go#L80

camilamacedo86

That is great 🎉start.
Thank you for looking on that.

We need ApplyConfigs to be optional. It must NOT be part of the default scaffold.

The idea is:

Add a new flag to kubebuilder create api, for example --applyconfiguration.
Only when this flag is used, we scaffold the Makefile target and the templates.
To do that, we add a new scaffold marker in the Makefile:
+kubebuilder:scaffold:applyconfiguration
All projects will contain this marker by default, but it is only replaced when the API is created with the flag. ( that would be a change in the Makefile template of the init command. All new project would need to have the marker for we wire or not things up )

How scaffold markers work:
https://book.kubebuilder.io/reference/markers/scaffold

When the user runs:
kubebuilder create api --applyconfiguration
we replace the marker with something like:

.PHONY: generate-applyconfigs
generate-applyconfigs: controller-gen
	"$(CONTROLLER_GEN)" \
		applyconfiguration:headerFile="hack/boilerplate.go.txt" \
		paths="./apis/..."

Also, the scaffolds for the APIs specific files need to be conditinal. I mean, by default nothing changes and will only change when we use create api first ( for all that is common base ) and only for the specific API scaffold for all that can be unique to that api

Add the new flag here:
https://github.com/kubernetes-sigs/kubebuilder/blob/master/pkg/plugins/golang/v4/api.go#L112-L121
Conditionally write the scaffold here (same as webhook logic):
https://github.com/kubernetes-sigs/kubebuilder/blob/master/pkg/plugins/golang/v4/scaffolds/api.go#L101-L102

Reference for conditional scaffolding (webhooks):
https://github.com/kubernetes-sigs/kubebuilder/blob/master/pkg/plugins/golang/v4/scaffolds/webhook.go#L106-L143

camilamacedo86 · 2025-11-20T06:00:08Z

pkg/plugins/golang/v4/scaffolds/api.go

 		if err := scaffold.Execute(
 			&api.Types{Force: s.force},
 			&api.Group{},
+			&api.Doc{},


We should only generate the new files if the/when the flag is informed

camilamacedo86 · 2025-11-20T06:02:56Z

pkg/plugins/golang/v4/scaffolds/internal/templates/makefile.go

+	"$(CONTROLLER_GEN)" applyconfiguration:headerFile="hack/boilerplate.go.txt" object:headerFile={{printf "%q" .BoilerplatePath}} paths="./..."
 	{{- else -}}
-	"$(CONTROLLER_GEN)" object paths="./..."
+	"$(CONTROLLER_GEN)" applyconfiguration object paths="./..."


So, here we should not do this change as well.
We should not change the default scaffold to be applyconfiguration

That would mean all would only work with.

So, the first question is:

In a project, can I have both?

Apis created with applyconfiguration and others not?
OR if we use applyconfiguration all APIs will need to generate with it?

camilamacedo86 · 2025-11-20T06:04:02Z

pkg/plugins/golang/v4/api.go

 		"if set, generate the resource without prompting the user")
 	p.resourceFlag = fs.Lookup("resource")
 	fs.BoolVar(&p.options.Namespaced, "namespaced", true, "resource is namespaced")
+	fs.BoolVar(&p.options.GenerateApplyConfiguration, "generate-apply-configuration", true, "if set, generate applyconfiguration code for the resource")


Can it be done per API or the whole project need to be changed to adopted this?
I mean, can I have 3 APIs that uses applyconfiguration and 3 that do not use them in the same project?
Is that possible?

camilamacedo86 · 2025-11-20T06:06:57Z

testdata/project-v4-multigroup/api/crew/v1/applyconfiguration/crew/v1/captainstatus.go

@@ -0,0 +1,47 @@
+/*


IN the testdata we should have no changes.
We should have all projects generate as before.
See that we have test/generate.sh

So, we would need to have a new mock using it and then yes we would only have the scaffold change for the specific API created with the flag. If we cannot have for example X APIs using it and X APIs using not then the change/flag cannot be in the API and it need to be in the edit and init commands ( such as we have multi-group option )

k8s-ci-robot requested review from camilamacedo86 and varshaprasad96 November 19, 2025 19:47

k8s-ci-robot added the cncf-cla: no Indicates the PR's author has not signed the CNCF CLA. label Nov 19, 2025

k8s-ci-robot added needs-ok-to-test Indicates a PR that requires an org member to verify it is safe to test. size/M Denotes a PR that changes 30-99 lines, ignoring generated files. labels Nov 19, 2025

k8s-ci-robot added cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. and removed cncf-cla: no Indicates the PR's author has not signed the CNCF CLA. labels Nov 19, 2025

yyewolf force-pushed the feat/applyconfiguration branch from 525e623 to 6ce9be5 Compare November 19, 2025 19:57

(feat) add necessary changes to support applyconfiguration gen

7166a19

yyewolf force-pushed the feat/applyconfiguration branch from 6ce9be5 to 7166a19 Compare November 19, 2025 19:58

camilamacedo86 reviewed Nov 19, 2025

View reviewed changes

yyewolf added 3 commits November 19, 2025 15:18

(fix) reverts breaking change on GroupVersion

8d51a9f

(feat) add an option for applyconfiguration

473f3ca

(feat) add makefile and set generation to enabled by default

c91bfa9

k8s-ci-robot added size/L Denotes a PR that changes 100-499 lines, ignoring generated files. and removed size/M Denotes a PR that changes 30-99 lines, ignoring generated files. labels Nov 19, 2025

yyewolf changed the title ~~⚠(feat): add necessary changes to support applyconfiguration gen~~ ✨(feat): add necessary changes to support applyconfiguration gen Nov 19, 2025

k8s-ci-robot added size/XXL Denotes a PR that changes 1000+ lines, ignoring generated files. and removed size/L Denotes a PR that changes 100-499 lines, ignoring generated files. labels Nov 19, 2025

camilamacedo86 requested changes Nov 20, 2025

View reviewed changes

yyewolf force-pushed the feat/applyconfiguration branch from bc37134 to c91bfa9 Compare November 20, 2025 15:41

k8s-ci-robot added size/L Denotes a PR that changes 100-499 lines, ignoring generated files. and removed size/XXL Denotes a PR that changes 1000+ lines, ignoring generated files. labels Nov 20, 2025

yyewolf marked this pull request as draft November 20, 2025 15:44

k8s-ci-robot added the do-not-merge/work-in-progress Indicates that a PR should not merge because it is a work in progress. label Nov 20, 2025

✨(feat): add necessary changes to support applyconfiguration gen #5237

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yyewolf commented Nov 19, 2025 •

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