Generate CRD in Go code

[chinglinwen]

CRD in Go code

I'd like to have crd write in go, and create crd when main.go runs, similar to this approach: https://github1s.com/k3s-io/helm-controller/blob/master/pkg/crd/crds.go

package crd

import (
	v1 "github.com/k3s-io/helm-controller/pkg/apis/helm.cattle.io/v1"
	"github.com/rancher/wrangler/v3/pkg/crd"
)

func List() []crd.CRD {
	chart := crd.NamespacedType("HelmChart.helm.cattle.io/v1").
		WithSchemaFromStruct(v1.HelmChart{}).
		WithColumn("Job", ".status.jobName").
		WithColumn("Chart", ".spec.chart").
		WithColumn("TargetNamespace", ".spec.targetNamespace").
		WithColumn("Version", ".spec.version").
		WithColumn("Repo", ".spec.repo").
		WithColumn("HelmVersion", ".spec.helmVersion").
		WithColumn("Bootstrap", ".spec.bootstrap").
		WithStatus()

	config := crd.NamespacedType("HelmChartConfig.helm.cattle.io/v1").
		WithSchemaFromStruct(v1.HelmChartConfig{})

	return []crd.CRD{chart, config}
}

https://github1s.com/k3s-io/helm-controller/blob/master/main.go#L60-L61

	ctx := cmd.Context()
	if err := wcrd.Create(ctx, clientConfig, crd.List()); err != nil {
		return err
	}

https://pkg.go.dev/github.com/rancher/wrangler/v3/pkg/crd

https://github.com/rancher/wrangler/blob/v3.1.0/pkg/crd/print.go#L57-L64

func Create(ctx context.Context, cfg *rest.Config, crds []CRD) error {
	factory, err := NewFactoryFromClient(cfg)
	if err != nil {
		return err
	}

	return factory.BatchCreateCRDs(ctx, crds...).BatchWait()
}

this way, it can be a lot simpler with a single deployment resource to apply.

would like kubebuilder to scaffold to generate such go file, and glue by main.go
say a file sit aside with types.go, maybe name: ${types}_crd_generated.go

[sbueringer]

This seems like a simple builder on top of the crd go type?

[chinglinwen]

this is just a example, I'd wish controller-gen can generated crd glue code in Go( so I can create crd when main.go started), rather than a bunch of yamls files.

[JoelSpeed]

You could embed the yaml file into the binary using a Go embedded FS, and marshal that into a CRD concrete type in your main.go, without any modification of how controller-tools works today

[chinglinwen]

It could works that way(workaround by embed YAMLs ), however this issue is about the more simpler way, and another difference is if generated in Go I'd expect, it doesn't need re-generate CRD ( since no generate CRD anymore ).

• https://pkg.go.dev/github.com/rancher/wrangler/v3/pkg/crd#CRD.WithSchemaFromStruct
• https://github.com/rancher/wrangler/blob/1345a309299c3e4aaf0f12188795b15978d5b9a2/pkg/crd/print.go#L57-L64

maybe a option first, to keep current behavior but with extra flag to tell controller-gen the switch from YAMLs to Go code etc.

[JoelSpeed]

it doesn't need re-generate CRD

That's a fair distinction

I'm not sure how simple this would actually be, there's a difference between generating structures to marshal into YAML, and then converting that to actual Go code. This would be a fairly major feature for controller tools and I think we would want to see a good number of requests for such a large feature before committing to it

Unless there's something I've missed that easily converts a structured Go type into a code that would represent the same obejct?