Implement generic patches in Kustomization

Allow patching multiple resources instead of a single existing one as
StrategicMerge & JSON6902 are forced to target existing named resources.

api/v1beta1/kustomization_types.go

@@ -83,6 +83,10 @@ type KustomizationSpec struct {
 	// +optional
 	HealthChecks []meta.NamespacedObjectKindReference `json:"healthChecks,omitempty"`
 
+	// Patches (also called overlays), defined as inline YAML objects.
+	// +optional
+	Patches []kustomize.Patch `json:"patches,omitempty"`
+
 	// Strategic merge patches, defined as inline YAML objects.
 	// +optional
 	PatchesStrategicMerge []apiextensionsv1.JSON `json:"patchesStrategicMerge,omitempty"`

config/crd/bases/kustomize.toolkit.fluxcd.io_kustomizations.yaml

@@ -142,6 +142,41 @@ spec:
                     - name
                     type: object
                 type: object
+              patches:
+                description: Patches (also called overlays), defined as inline YAML objects.
+                items:
+                  description: Patch contains either a StrategicMerge or a JSON6902 patch, either a file or inline, and the target the patch should be applied to.
+                  properties:
+                    patch:
+                      description: Patch contains the JSON6902 patch document with an array of operation objects.
+                      type: string
+                    target:
+                      description: Target points to the resources that the patch document should be applied to.
+                      properties:
+                        annotationSelector:
+                          description: AnnotationSelector is a string that follows the label selection expression https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#api It matches with the resource annotations.
+                          type: string
+                        group:
+                          description: Group is the API group to select resources from. Together with Version and Kind it is capable of unambiguously identifying and/or selecting resources. https://github.com/kubernetes/community/blob/master/contributors/design-proposals/api-machinery/api-group.md
+                          type: string
+                        kind:
+                          description: Kind of the API Group to select resources from. Together with Group and Version it is capable of unambiguously identifying and/or selecting resources. https://github.com/kubernetes/community/blob/master/contributors/design-proposals/api-machinery/api-group.md
+                          type: string
+                        labelSelector:
+                          description: LabelSelector is a string that follows the label selection expression https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#api It matches with the resource labels.
+                          type: string
+                        name:
+                          description: Name to match resources with.
+                          type: string
+                        namespace:
+                          description: Namespace to select resources from.
+                          type: string
+                        version:
+                          description: Version of the API Group to select resources from. Together with Group and Kind it is capable of unambiguously identifying and/or selecting resources. https://github.com/kubernetes/community/blob/master/contributors/design-proposals/api-machinery/api-group.md
+                          type: string
+                      type: object
+                  type: object
+                type: array
               patchesJson6902:
                 description: JSON 6902 patches, defined as inline YAML objects.
                 items:

controllers/kustomization_controller_patch_test.go

@@ -144,10 +144,62 @@ var _ = Describe("KustomizationReconciler", func() {
 			Expect(deployment.Spec.Template.Spec.Containers[0].Image).To(Equal("ghcr.io/stefanprodan/podinfo:5.2.0"))
 		})
 
+		It("patches as JSON", func() {
+			kustomization.Spec.Patches = []kustomize.Patch{
+				{
+					Patch: `
+- op: add
+  path: /metadata/labels/patch
+  value: inline-json
+						`,
+					Target: kustomize.Selector{
+						LabelSelector: "app=podinfo",
+					},
+				},
+			}
+			Expect(k8sClient.Create(context.TODO(), kustomization)).To(Succeed())
+
+			Eventually(func() bool {
+				var obj kustomizev1.Kustomization
+				_ = k8sClient.Get(context.Background(), ObjectKey(kustomization), &obj)
+				return obj.Status.LastAppliedRevision == "main/"+artifactChecksum
+			}, timeout, time.Second).Should(BeTrue())
+
+			var deployment appsv1.Deployment
+			Expect(k8sClient.Get(context.TODO(), client.ObjectKey{Name: "podinfo", Namespace: namespace.Name}, &deployment)).To(Succeed())
+			Expect(deployment.ObjectMeta.Labels["patch"]).To(Equal("inline-json"))
+		})
+
+		It("patches as YAML", func() {
+			kustomization.Spec.Patches = []kustomize.Patch{
+				{
+					Patch: `
+apiVersion: v1
+kind: Pod
+metadata:
+  name: podinfo
+  labels:
+    patch: inline-yaml
+						`,
+				},
+			}
+			Expect(k8sClient.Create(context.TODO(), kustomization)).To(Succeed())
+
+			Eventually(func() bool {
+				var obj kustomizev1.Kustomization
+				_ = k8sClient.Get(context.Background(), ObjectKey(kustomization), &obj)
+				return obj.Status.LastAppliedRevision == "main/"+artifactChecksum
+			}, timeout, time.Second).Should(BeTrue())
+
+			var deployment appsv1.Deployment
+			Expect(k8sClient.Get(context.TODO(), client.ObjectKey{Name: "podinfo", Namespace: namespace.Name}, &deployment)).To(Succeed())
+			Expect(deployment.ObjectMeta.Labels["patch"]).To(Equal("inline-yaml"))
+		})
+
 		It("strategic merge patches", func() {
 			kustomization.Spec.PatchesStrategicMerge = []apiextensionsv1.JSON{
 				{
-					Raw: []byte(`{"kind":"Deployment","apiVersion":"apps/v1","metadata":{"name":"podinfo","labels":{"xxxx":"yyyy"}}}`),
+					Raw: []byte(`{"kind":"Deployment","apiVersion":"apps/v1","metadata":{"name":"podinfo","labels":{"patch":"strategic-merge"}}}`),
 				},
 			}
 			Expect(k8sClient.Create(context.TODO(), kustomization)).To(Succeed())
@@ -160,15 +212,14 @@ var _ = Describe("KustomizationReconciler", func() {
 
 			var deployment appsv1.Deployment
 			Expect(k8sClient.Get(context.TODO(), client.ObjectKey{Name: "podinfo", Namespace: namespace.Name}, &deployment)).To(Succeed())
-			Expect(deployment.ObjectMeta.Labels["xxxx"]).To(Equal("yyyy"))
+			Expect(deployment.ObjectMeta.Labels["patch"]).To(Equal("strategic-merge"))
 		})
 
 		It("JSON6902 patches", func() {
 			kustomization.Spec.PatchesJSON6902 = []kustomize.JSON6902Patch{
 				{
-
 					Patch: []kustomize.JSON6902{
-						{Op: "add", Path: "/metadata/labels/yyyy", Value: &apiextensionsv1.JSON{Raw: []byte(`"xxxx"`)}},
+						{Op: "add", Path: "/metadata/labels/patch", Value: &apiextensionsv1.JSON{Raw: []byte(`"json6902"`)}},
 						{Op: "replace", Path: "/spec/replicas", Value: &apiextensionsv1.JSON{Raw: []byte("2")}},
 					},
 					Target: kustomize.Selector{
@@ -189,7 +240,7 @@ var _ = Describe("KustomizationReconciler", func() {
 
 			var deployment appsv1.Deployment
 			Expect(k8sClient.Get(context.TODO(), client.ObjectKey{Name: "podinfo", Namespace: namespace.Name}, &deployment)).To(Succeed())
-			Expect(deployment.ObjectMeta.Labels["yyyy"]).To(Equal("xxxx"))
+			Expect(deployment.ObjectMeta.Labels["patch"]).To(Equal("json6902"))
 			Expect(*deployment.Spec.Replicas).To(Equal(int32(2)))
 		})
 	})

controllers/kustomization_generator.go

@@ -104,6 +104,13 @@ func (kg *KustomizeGenerator) WriteFile(ctx context.Context, dirPath string) (st
 		kus.Namespace = kg.kustomization.Spec.TargetNamespace
 	}
 
+	for _, m := range kg.kustomization.Spec.Patches {
+		kus.Patches = append(kus.Patches, kustypes.Patch{
+			Patch:  m.Patch,
+			Target: adaptSelector(&m.Target),
+		})
+	}
+
 	for _, m := range kg.kustomization.Spec.PatchesStrategicMerge {
 		kus.PatchesStrategicMerge = append(kus.PatchesStrategicMerge, kustypes.PatchStrategicMerge(m.Raw))
 	}

docs/api/kustomize.md

@@ -198,6 +198,20 @@ bool
 </tr>
 <tr>
 <td>
+<code>patches</code><br>
+<em>
+<a href="https://godoc.org/github.com/fluxcd/pkg/apis/kustomize#Patch">
+[]github.com/fluxcd/pkg/apis/kustomize.Patch
+</a>
+</em>
+</td>
+<td>
+<em>(Optional)</em>
+<p>Patches (also called overlays), defined as inline YAML objects.</p>
+</td>
+</tr>
+<tr>
+<td>
 <code>patchesStrategicMerge</code><br>
 <em>
 <a href="https://pkg.go.dev/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1?tab=doc#JSON">
@@ -657,6 +671,20 @@ bool
 </tr>
 <tr>
 <td>
+<code>patches</code><br>
+<em>
+<a href="https://godoc.org/github.com/fluxcd/pkg/apis/kustomize#Patch">
+[]github.com/fluxcd/pkg/apis/kustomize.Patch
+</a>
+</em>
+</td>
+<td>
+<em>(Optional)</em>
+<p>Patches (also called overlays), defined as inline YAML objects.</p>
+</td>
+</tr>
+<tr>
+<td>
 <code>patchesStrategicMerge</code><br>
 <em>
 <a href="https://pkg.go.dev/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1?tab=doc#JSON">

docs/spec/v1beta1/kustomization.md

@@ -598,14 +598,15 @@ The Kustomization has a set of fields to extend and/or override the Kustomize
 patches and namespace on all the Kubernetes objects reconciled by the resource,
 offering support for the following Kustomize directives:
 
-- [namespace](https://kubectl.docs.kubernetes.io/references/kustomize/namespace/)
+- [namespace](https://kubectl.docs.kubernetes.io/references/kustomize/kustomization/namespace/)
+- [patches](https://kubectl.docs.kubernetes.io/references/kustomize/kustomization/patches/)
 - [patchesStrategicMerge](https://kubectl.docs.kubernetes.io/references/kustomize/patchesstrategicmerge/)
-- [patchesJson6902](https://kubectl.docs.kubernetes.io/references/kustomize/patchesjson6902/)
-- [images](https://kubectl.docs.kubernetes.io/references/kustomize/images/)
+- [patchesJson6902](https://kubectl.docs.kubernetes.io/references/kustomize/kustomization/patchesjson6902/)
+- [images](https://kubectl.docs.kubernetes.io/references/kustomize/kustomization/images/)
 
 ### Target namespace
 
-To configure the [Kustomize `namespace`](https://kubectl.docs.kubernetes.io/references/kustomize/namespace/)
+To configure the [Kustomize `namespace`](https://kubectl.docs.kubernetes.io/references/kustomize/kustomization/namespace/)
 and overwrite the namespace of all the Kubernetes objects reconciled by the `Kustomization`,
 `spec.targetNamespace` can be defined:
 
@@ -622,9 +623,35 @@ spec:
 
 The `targetNamespace` is expected to exist.
 
+### Patches
+
+To add [Kustomize `patches` entries](https://kubectl.docs.kubernetes.io/references/kustomize/kustomization/patches/)
+to the configuration, and patch resources using either a [strategic merge](https://kubectl.docs.kubernetes.io/references/kustomize/glossary#patchstrategicmerge) 
+patch or a [JSON](https://kubectl.docs.kubernetes.io/references/kustomize/glossary#patchjson6902) patch,
+`spec.patches` items must contain a `target` selector and a `patch` document.
+The patch can target a single resource or multiple resources
+
+```yaml
+apiVersion: kustomize.toolkit.fluxcd.io/v1beta1
+kind: Kustomization
+metadata:
+  name: podinfo
+  namespace: flux-system
+spec:
+  # ...omitted for brevity
+  patches:
+    - patch: |-
+        apiVersion: v1
+        kind: Pod
+        metadata:
+          name: dummy-app
+          labels:
+            app.kubernetes.io/part-of: test-app
+```
+
 ### Strategic Merge patches
 
-To add [Kustomize `patchesStrategicMerge` entries](https://kubectl.docs.kubernetes.io/references/kustomize/patchesstrategicmerge/)
+To add [Kustomize `patchesStrategicMerge` entries](https://kubectl.docs.kubernetes.io/references/kustomize/kustomization/patchesstrategicmerge/)
 to the configuration, `spec.patchesStrategicMerge` can be defined with a list
 of strategic merge patches in YAML format:
 
@@ -649,7 +676,7 @@ spec:
 
 ### JSON 6902 patches
 
-To add [Kustomize `patchesJson6902` entries](https://kubectl.docs.kubernetes.io/references/kustomize/patchesjson6902/)
+To add [Kustomize `patchesJson6902` entries](https://kubectl.docs.kubernetes.io/references/kustomize/kustomization/patchesjson6902/)
 to the configuration, and patch resources using the [JSON 6902 standard](https://tools.ietf.org/html/rfc6902),
 `spec.patchesJson6902`, the items must contain a `target` selector and JSON 6902
 `patch` document:
@@ -675,7 +702,7 @@ spec:
 
 ### Images
 
-To add [Kustomize `images` entries](https://kubectl.docs.kubernetes.io/references/kustomize/images/)
+To add [Kustomize `images` entries](https://kubectl.docs.kubernetes.io/references/kustomize/kustomization/images/)
 to the configuration, and overwrite the name, tag or digest of container images
 without creating patches, `spec.images` can be defined: