Label release resources with HelmRelease origin

This commit adds a new post renderer that labels all resources with
`helm.toolkit.fluxcd.io/name` and `helm.toolkit.fluxcd.io/namespace`
so their source of origin can be traced back by e.g. the Flux UI.

The post renderer makes use of the Kustomize API without running
a full Kustomize build, by making directly use of the builtin
`LabelTransformerPlugin` on a `ResMap` that has been constructed
from the bytes of the `bytes.Buffer` given by Helm.

Signed-off-by: Hidde Beydals <hello@hidde.co>

internal/runner/post_renderer_origin_labels.go

@@ -0,0 +1,76 @@
+/*
+Copyright 2021 The Flux authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package runner
+
+import (
+	"bytes"
+	"fmt"
+
+	"sigs.k8s.io/kustomize/api/builtins"
+	"sigs.k8s.io/kustomize/api/k8sdeps/kunstruct"
+	"sigs.k8s.io/kustomize/api/resmap"
+	"sigs.k8s.io/kustomize/api/resource"
+	kustypes "sigs.k8s.io/kustomize/api/types"
+
+	v2 "github.com/fluxcd/helm-controller/api/v2beta1"
+)
+
+func newPostRendererOriginLabels(release *v2.HelmRelease) *postRendererOriginLabels {
+	return &postRendererOriginLabels{
+		name:      release.ObjectMeta.Name,
+		namespace: release.ObjectMeta.Namespace,
+	}
+}
+
+type postRendererOriginLabels struct {
+	name      string
+	namespace string
+}
+
+func (k *postRendererOriginLabels) Run(renderedManifests *bytes.Buffer) (modifiedManifests *bytes.Buffer, err error) {
+	resFactory := resource.NewFactory(kunstruct.NewKunstructuredFactoryImpl())
+	resMapFactory := resmap.NewFactory(resFactory, nil)
+
+	resMap, err := resMapFactory.NewResMapFromBytes(renderedManifests.Bytes())
+	if err != nil {
+		return nil, err
+	}
+
+	labelTransformer := builtins.LabelTransformerPlugin{
+		Labels: originLabels(k.name, k.namespace),
+		FieldSpecs: []kustypes.FieldSpec{
+			{Path: "metadata/labels", CreateIfNotPresent: true},
+		},
+	}
+	if err := labelTransformer.Transform(resMap); err != nil {
+		return nil, err
+	}
+
+	yaml, err := resMap.AsYaml()
+	if err != nil {
+		return nil, err
+	}
+
+	return bytes.NewBuffer(yaml), nil
+}
+
+func originLabels(name, namespace string) map[string]string {
+	return map[string]string{
+		fmt.Sprintf("%s/name", v2.GroupVersion.Group):      name,
+		fmt.Sprintf("%s/namespace", v2.GroupVersion.Group): namespace,
+	}
+}

internal/runner/post_renderer_origin_labels_test.go

@@ -0,0 +1,83 @@
+/*
+Copyright 2021 The Flux authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package runner
+
+import (
+	"bytes"
+	"reflect"
+	"testing"
+)
+
+const mixedResourceMock = `apiVersion: v1
+kind: Pod
+metadata:
+  name: pod-without-labels
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: service-with-labels
+  labels:
+    existing: label
+`
+
+func Test_postRendererOriginLabels_Run(t *testing.T) {
+	tests := []struct {
+		name              string
+		renderedManifests string
+		expectManifests   string
+		expectErr         bool
+	}{
+		{
+			name:              "labels",
+			renderedManifests: mixedResourceMock,
+			expectManifests: `apiVersion: v1
+kind: Pod
+metadata:
+  labels:
+    helm.toolkit.fluxcd.io/name: name
+    helm.toolkit.fluxcd.io/namespace: namespace
+  name: pod-without-labels
+---
+apiVersion: v1
+kind: Service
+metadata:
+  labels:
+    existing: label
+    helm.toolkit.fluxcd.io/name: name
+    helm.toolkit.fluxcd.io/namespace: namespace
+  name: service-with-labels
+`,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			k := &postRendererOriginLabels{
+				name:      "name",
+				namespace: "namespace",
+			}
+			gotModifiedManifests, err := k.Run(bytes.NewBufferString(tt.renderedManifests))
+			if (err != nil) != tt.expectErr {
+				t.Errorf("Run() error = %v, expectErr %v", err, tt.expectErr)
+				return
+			}
+			if !reflect.DeepEqual(gotModifiedManifests, bytes.NewBufferString(tt.expectManifests)) {
+				t.Errorf("Run() gotModifiedManifests = %v, want %v", gotModifiedManifests, tt.expectManifests)
+			}
+		})
+	}
+}

internal/runner/runner.go

@@ -58,6 +58,7 @@ func postRenderers(hr v2.HelmRelease) (postrender.PostRenderer, error) {
 			combinedRenderer.addRenderer(newPostRendererKustomize(r.Kustomize))
 		}
 	}
+	combinedRenderer.addRenderer(newPostRendererOriginLabels(&hr))
 	if len(combinedRenderer.renderers) == 0 {
 		return nil, nil
 	}