Add shared Kubernetes decode and patch helpers

Author: CMGS

k8s/patch.go

@@ -0,0 +1,22 @@
+package k8s
+
+import "encoding/json"
+
+// MergePatch marshals a payload as a Kubernetes merge patch document.
+func MergePatch(payload any) ([]byte, error) {
+	return json.Marshal(payload)
+}
+
+// StatusMergePatch builds a merge patch for a status subresource update.
+func StatusMergePatch(status any) ([]byte, error) {
+	return MergePatch(map[string]any{"status": status})
+}
+
+// MetadataAnnotationsMergePatch builds a merge patch for annotation updates.
+func MetadataAnnotationsMergePatch(annotations map[string]any) ([]byte, error) {
+	return MergePatch(map[string]any{
+		"metadata": map[string]any{
+			"annotations": annotations,
+		},
+	})
+}

k8s/unstructured.go

@@ -0,0 +1,17 @@
+package k8s
+
+import (
+	"fmt"
+
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	"k8s.io/apimachinery/pkg/runtime"
+)
+
+// DecodeUnstructured converts an unstructured Kubernetes object into a typed value.
+func DecodeUnstructured[T any](u *unstructured.Unstructured) (*T, error) {
+	var out T
+	if err := runtime.DefaultUnstructuredConverter.FromUnstructured(u.Object, &out); err != nil {
+		return nil, fmt.Errorf("decode %T: %w", out, err)
+	}
+	return &out, nil
+}

k8s/unstructured_test.go

@@ -0,0 +1,73 @@
+package k8s
+
+import (
+	"encoding/json"
+	"testing"
+
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+)
+
+func TestDecodeUnstructured(t *testing.T) {
+	type spec struct {
+		Name string `json:"name"`
+	}
+	type sample struct {
+		Spec spec `json:"spec"`
+	}
+
+	obj := &unstructured.Unstructured{
+		Object: map[string]any{
+			"spec": map[string]any{
+				"name": "demo",
+			},
+		},
+	}
+
+	got, err := DecodeUnstructured[sample](obj)
+	if err != nil {
+		t.Fatalf("DecodeUnstructured returned error: %v", err)
+	}
+	if got.Spec.Name != "demo" {
+		t.Fatalf("decoded name mismatch: got %q", got.Spec.Name)
+	}
+}
+
+func TestStatusMergePatch(t *testing.T) {
+	data, err := StatusMergePatch(map[string]string{"phase": "Ready"})
+	if err != nil {
+		t.Fatalf("StatusMergePatch returned error: %v", err)
+	}
+
+	var patch map[string]map[string]string
+	if err := json.Unmarshal(data, &patch); err != nil {
+		t.Fatalf("unmarshal patch: %v", err)
+	}
+	if got := patch["status"]["phase"]; got != "Ready" {
+		t.Fatalf("status phase mismatch: got %q", got)
+	}
+}
+
+func TestMetadataAnnotationsMergePatch(t *testing.T) {
+	data, err := MetadataAnnotationsMergePatch(map[string]any{
+		"cocoon.cis/hibernate": nil,
+		"cocoon.cis/vm-name":   "vk-demo-0",
+	})
+	if err != nil {
+		t.Fatalf("MetadataAnnotationsMergePatch returned error: %v", err)
+	}
+
+	var patch struct {
+		Metadata struct {
+			Annotations map[string]any `json:"annotations"`
+		} `json:"metadata"`
+	}
+	if err := json.Unmarshal(data, &patch); err != nil {
+		t.Fatalf("unmarshal patch: %v", err)
+	}
+	if got := patch.Metadata.Annotations["cocoon.cis/vm-name"]; got != "vk-demo-0" {
+		t.Fatalf("vm-name mismatch: got %#v", got)
+	}
+	if got := patch.Metadata.Annotations["cocoon.cis/hibernate"]; got != nil {
+		t.Fatalf("expected nil patch value, got %#v", got)
+	}
+}