feat: add kubernetes cluster access and listing crds in the cluster

Signed-off-by: Gergely Brautigam <[email protected]>

Author: Skarlso

README.md

@@ -140,6 +140,21 @@ cty generate crd -r folder
 
 Any other flag will work as before.
 
+### Kubernetes Config
+
+Use `cty` to search for a resource in an existing Kubernetes Cluster.
+
+```
+cty generate crd -k krokcommands.delivery.krok.app
+```
+
+This will look for this CRD in the cluster and generate a sample file for it. If you wish to use a different resource
+that supports `openAPIV3Schema` you can configure the group/version/resource `cty` is looking for.
+
+```
+cty generate crd -k xxtstorageaccounts.crossplane.fnietoga.me --resource CompositeResourceDefinition --group apiextensions.crossplane.io --version v1
+```
+
 ### Config File
 
 It's possible to define a config file that designates groups for various rendered CRDs.

cmd/crd.go

@@ -128,6 +128,13 @@ func constructHandler(args *rootArgs) (Handler, error) {
 	var crdHandler Handler
 
 	switch {
+	case args.kubeCluster != "":
+		crdHandler = &KubeHandler{
+			crd:             args.kubeCluster,
+			resourceGroup:   args.group,
+			resourceVersion: args.version,
+			resource:        args.resource,
+		}
 	case args.stdin:
 		crdHandler = &StdInHandler{}
 	case args.fileLocation != "":

cmd/generate.go

@@ -15,8 +15,12 @@ type rootArgs struct {
 	tag                string
 	caBundle           string
 	privSSHKey         string
-	useSSHAgent        bool
 	gitURL             string
+	kubeCluster        string
+	group              string
+	version            string
+	resource           string
+	useSSHAgent        bool
 	stdin              bool
 }
 
@@ -36,6 +40,7 @@ func init() {
 	f := generateCmd.PersistentFlags()
 	f.BoolVarP(&args.stdin, "stdin", "i", false, "Take CRD content from stdin.")
 	f.StringVarP(&args.fileLocation, "crd", "c", "", "The CRD file to generate a yaml from.")
+	f.StringVarP(&args.kubeCluster, "kube", "k", "", "Try to access the local cluster and fetch CRD content from there.")
 	f.StringVarP(&args.folderLocation, "folder", "r", "", "A folder from which to parse a series of CRDs.")
 	f.StringVarP(&args.url, "url", "u", "", "If provided, will use this URL to fetch CRD YAML content from.")
 	f.StringVarP(&args.gitURL, "git-url", "g", "", "If provided, CRDs will be discovered using a git repository.")
@@ -47,4 +52,7 @@ func init() {
 	f.StringVar(&args.caBundle, "ca-bundle-file", "", "Additional certificate bundle to load. Should the name of the file.")
 	f.StringVar(&args.privSSHKey, "private-ssh-key-file", "", "Private key to use for cloning. Should the name of the file.")
 	f.BoolVar(&args.useSSHAgent, "ssh-agent", false, "If set, the configured SSH agent will be used to clone the repository..")
+	f.StringVar(&args.group, "group", "apiextensions.k8s.io", "If set, it will look for this group when using Kubernetes Config.")
+	f.StringVar(&args.version, "version", "v1", "If set, it will look for this version when using Kubernetes Config.")
+	f.StringVar(&args.resource, "resource", "customresourcedefinitions", "If set, it will look for this version when using Kubernetes Config.")
 }

cmd/kube_handler.go

@@ -0,0 +1,65 @@
+package cmd
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/client-go/dynamic"
+	"k8s.io/client-go/tools/clientcmd"
+	"k8s.io/client-go/util/homedir"
+
+	"github.com/Skarlso/crd-to-sample-yaml/pkg"
+)
+
+type KubeHandler struct {
+	crd             string
+	group           string
+	resourceGroup   string
+	resourceVersion string
+	resource        string
+}
+
+func (h *KubeHandler) CRDs() ([]*pkg.SchemaType, error) {
+	kubeconfig := os.Getenv("KUBECONFIG")
+	if kubeconfig == "" {
+		kubeconfig = filepath.Join(homedir.HomeDir(), ".kube", "config")
+	}
+
+	config, err := clientcmd.BuildConfigFromFlags("", kubeconfig)
+	if err != nil {
+		return nil, fmt.Errorf("error building config from flags: %w", err)
+	}
+	cliSet, err := dynamic.NewForConfig(config)
+	if err != nil {
+		return nil, fmt.Errorf("error creating dynamic client: %w", err)
+	}
+	ctx := context.Background()
+
+	result, err := cliSet.Resource(schema.GroupVersionResource{
+		Group:    h.resourceGroup,
+		Version:  h.resourceVersion,
+		Resource: h.resource,
+	}).Get(ctx, h.crd, metav1.GetOptions{})
+	if err != nil {
+		return nil, fmt.Errorf("error getting CRD: %w", err)
+	}
+
+	schemaType, err := pkg.ExtractSchemaType(result)
+	if err != nil {
+		return nil, fmt.Errorf("failed to extract schema type: %w", err)
+	}
+
+	if schemaType == nil {
+		return nil, nil
+	}
+
+	if h.group != "" {
+		schemaType.Rendering = pkg.Rendering{Group: h.group}
+	}
+
+	return []*pkg.SchemaType{schemaType}, nil
+}

go.mod

@@ -16,6 +16,7 @@ require (
 	github.com/stretchr/testify v1.10.0
 	k8s.io/apiextensions-apiserver v0.32.2
 	k8s.io/apimachinery v0.32.2
+	k8s.io/client-go v0.32.2
 )
 
 require (
@@ -78,6 +79,7 @@ require (
 	golang.org/x/net v0.35.0 // indirect
 	golang.org/x/oauth2 v0.24.0 // indirect
 	golang.org/x/sys v0.30.0 // indirect
+	golang.org/x/term v0.29.0 // indirect
 	golang.org/x/text v0.22.0 // indirect
 	golang.org/x/time v0.8.0 // indirect
 	google.golang.org/genproto/googleapis/api v0.0.0-20240826202546-f6391c0de4c7 // indirect