Merge pull request #2168 from pgpx/feature-kustomizationpatch

Implement "kind: Component" to support composition

api/internal/target/kusttarget.go

@@ -166,11 +166,21 @@ func (kt *KustTarget) addHashesToNames(
 // not yet fixed.
 func (kt *KustTarget) AccumulateTarget() (
 	ra *accumulator.ResAccumulator, err error) {
-	ra = accumulator.MakeEmptyAccumulator()
-	err = kt.accumulateResources(ra, kt.kustomization.Resources)
+	return kt.accumulateTarget(accumulator.MakeEmptyAccumulator())
+}
+
+// ra should be empty when this KustTarget is a Kustomization, or the ra of the parent if this KustTarget is a Component
+// (or empty if the Component does not have a parent).
+func (kt *KustTarget) accumulateTarget(ra *accumulator.ResAccumulator) (
+	resRa *accumulator.ResAccumulator, err error) {
+	ra, err = kt.accumulateResources(ra, kt.kustomization.Resources)
 	if err != nil {
 		return nil, errors.Wrap(err, "accumulating resources")
 	}
+	ra, err = kt.accumulateComponents(ra, kt.kustomization.Components)
+	if err != nil {
+		return nil, errors.Wrap(err, "accumulating components")
+	}
 	tConfig, err := builtinconfig.MakeTransformerConfig(
 		kt.ldr, kt.kustomization.Configurations)
 	if err != nil {
@@ -235,7 +245,7 @@ func (kt *KustTarget) runGenerators(
 
 func (kt *KustTarget) configureExternalGenerators() ([]resmap.Generator, error) {
 	ra := accumulator.MakeEmptyAccumulator()
-	err := kt.accumulateResources(ra, kt.kustomization.Generators)
+	ra, err := kt.accumulateResources(ra, kt.kustomization.Generators)
 	if err != nil {
 		return nil, err
 	}
@@ -261,7 +271,7 @@ func (kt *KustTarget) runTransformers(ra *accumulator.ResAccumulator) error {
 
 func (kt *KustTarget) configureExternalTransformers() ([]resmap.Transformer, error) {
 	ra := accumulator.MakeEmptyAccumulator()
-	err := kt.accumulateResources(ra, kt.kustomization.Transformers)
+	ra, err := kt.accumulateResources(ra, kt.kustomization.Transformers)
 	if err != nil {
 		return nil, err
 	}
@@ -271,44 +281,81 @@ func (kt *KustTarget) configureExternalTransformers() ([]resmap.Transformer, err
 // accumulateResources fills the given resourceAccumulator
 // with resources read from the given list of paths.
 func (kt *KustTarget) accumulateResources(
-	ra *accumulator.ResAccumulator, paths []string) error {
+	ra *accumulator.ResAccumulator, paths []string) (*accumulator.ResAccumulator, error) {
 	for _, path := range paths {
 		// try loading resource as file then as base (directory or git repository)
 		if errF := kt.accumulateFile(ra, path); errF != nil {
 			ldr, errL := kt.ldr.New(path)
 			if errL != nil {
-				return fmt.Errorf("accumulateFile %q, loader.New %q", errF, errL)
+				return nil, fmt.Errorf("accumulateFile %q, loader.New %q", errF, errL)
 			}
-			errD := kt.accumulateDirectory(ra, ldr)
+			var errD error
+			ra, errD = kt.accumulateDirectory(ra, ldr, false)
 			if errD != nil {
-				return fmt.Errorf("accumulateFile %q, accumulateDirector: %q", errF, errD)
+				return nil, fmt.Errorf("accumulateFile %q, accumulateDirector: %q", errF, errD)
 			}
 		}
 	}
-	return nil
+	return ra, nil
+}
+
+// accumulateResources fills the given resourceAccumulator
+// with resources read from the given list of paths.
+func (kt *KustTarget) accumulateComponents(
+	ra *accumulator.ResAccumulator, paths []string) (*accumulator.ResAccumulator, error) {
+	for _, path := range paths {
+		// Components always refer to directories
+		ldr, errL := kt.ldr.New(path)
+		if errL != nil {
+			return nil, fmt.Errorf("loader.New %q", errL)
+		}
+		var errD error
+		ra, errD = kt.accumulateDirectory(ra, ldr, true)
+		if errD != nil {
+			return nil, fmt.Errorf("accumulateDirectory: %q", errD)
+		}
+	}
+	return ra, nil
 }
 
 func (kt *KustTarget) accumulateDirectory(
-	ra *accumulator.ResAccumulator, ldr ifc.Loader) error {
+	ra *accumulator.ResAccumulator, ldr ifc.Loader, isComponent bool) (*accumulator.ResAccumulator, error) {
 	defer ldr.Cleanup()
 	subKt := NewKustTarget(
 		ldr, kt.validator, kt.rFactory, kt.tFactory, kt.pLdr)
 	err := subKt.Load()
 	if err != nil {
-		return errors.Wrapf(
+		return nil, errors.Wrapf(
 			err, "couldn't make target for path '%s'", ldr.Root())
 	}
-	subRa, err := subKt.AccumulateTarget()
+	if isComponent && subKt.kustomization.Kind != types.ComponentKind {
+		return nil, fmt.Errorf(
+			"expected kind '%s' for path '%s' but got '%s'", types.ComponentKind, ldr.Root(), subKt.kustomization.Kind)
+	} else if !isComponent && subKt.kustomization.Kind == types.ComponentKind {
+		return nil, fmt.Errorf(
+			"expected kind != '%s' for path '%s'", types.ComponentKind, ldr.Root())
+	}
+
+	var subRa *accumulator.ResAccumulator
+	if isComponent {
+		// Components don't create a new accumulator: the kustomization directives are added to the current accumulator
+		subRa, err = subKt.accumulateTarget(ra)
+		ra = accumulator.MakeEmptyAccumulator()
+	} else {
+		// Child Kustomizations create a new accumulator which resolves their kustomization directives, which will later
+		// be merged into the current accumulator.
+		subRa, err = subKt.AccumulateTarget()
+	}
 	if err != nil {
-		return errors.Wrapf(
+		return nil, errors.Wrapf(
 			err, "recursed accumulation of path '%s'", ldr.Root())
 	}
 	err = ra.MergeAccumulator(subRa)
 	if err != nil {
-		return errors.Wrapf(
+		return nil, errors.Wrapf(
 			err, "recursed merging from path '%s'", ldr.Root())
 	}
-	return nil
+	return ra, nil
 }
 
 func (kt *KustTarget) accumulateFile(

api/krusty/component_test.go

@@ -0,0 +1,670 @@
+// Copyright 2020 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package krusty_test
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"sigs.k8s.io/kustomize/api/konfig"
+	kusttest_test "sigs.k8s.io/kustomize/api/testutils/kusttest"
+)
+
+type FileGen func(kusttest_test.Harness)
+
+func writeC(path string, content string) FileGen {
+	return func(th kusttest_test.Harness) {
+		th.WriteC(path, content)
+	}
+}
+
+func writeF(path string, content string) FileGen {
+	return func(th kusttest_test.Harness) {
+		th.WriteF(path, content)
+	}
+}
+
+func writeK(path string, content string) FileGen {
+	return func(th kusttest_test.Harness) {
+		th.WriteK(path, content)
+	}
+}
+
+func writeTestBase(th kusttest_test.Harness) {
+	th.WriteK("/app/base", `
+resources:
+- deploy.yaml
+configMapGenerator:
+- name: my-configmap
+  literals:	
+    - testValue=1
+    - otherValue=10
+`)
+	th.WriteF("/app/base/deploy.yaml", `
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: storefront
+spec:
+  replicas: 1
+`)
+}
+
+func writeTestComponent(th kusttest_test.Harness) {
+	th.WriteC("/app/comp", `
+namePrefix: comp-
+replicas:
+- name: storefront
+  count: 3
+resources:
+  - stub.yaml
+configMapGenerator:
+- name: my-configmap
+  behavior: merge
+  literals:	
+    - testValue=2
+    - compValue=5
+`)
+	th.WriteF("/app/comp/stub.yaml", `
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: stub
+spec:
+  replicas: 1
+`)
+}
+
+func writeOverlayProd(th kusttest_test.Harness) {
+	th.WriteK("/app/prod", `
+resources:
+- ../base
+- db
+
+components:
+- ../comp
+`)
+	writeDB(th)
+}
+
+func writeDB(th kusttest_test.Harness) {
+	deployment("db", "/app/prod/db")(th)
+}
+
+func deployment(name string, path string) FileGen {
+	return writeF(path, fmt.Sprintf(`
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: %s
+spec:
+  type: Logical
+`, name))
+}
+
+func TestComponent(t *testing.T) {
+	testCases := map[string]struct {
+		input          []FileGen
+		runPath        string
+		expectedOutput string
+	}{
+		// Components are inserted into the resource hierarchy as the parent of those
+		// resources that come before it in the resources list of the parent Kustomization.
+		"basic-component": {
+			input:   []FileGen{writeTestBase, writeTestComponent, writeOverlayProd},
+			runPath: "/app/prod",
+			expectedOutput: `
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: comp-storefront
+spec:
+  replicas: 3
+---
+apiVersion: v1
+data:
+  compValue: "5"
+  otherValue: "10"
+  testValue: "2"
+kind: ConfigMap
+metadata:
+  annotations: {}
+  labels: {}
+  name: comp-my-configmap-ct5bgtbccd
+---
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: comp-db
+spec:
+  type: Logical
+---
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: comp-stub
+spec:
+  replicas: 1
+`,
+		},
+		"multiple-components": {
+			input: []FileGen{writeTestBase, writeTestComponent, writeDB,
+				writeC("/app/additionalcomp", `
+configMapGenerator:
+- name: my-configmap
+  behavior: merge
+  literals:	
+    - otherValue=9
+`),
+				writeK("/app/prod", `
+resources:
+- ../base
+- db
+
+components:
+- ../comp
+- ../additionalcomp
+`),
+			},
+			runPath: "/app/prod",
+			expectedOutput: `
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: comp-storefront
+spec:
+  replicas: 3
+---
+apiVersion: v1
+data:
+  compValue: "5"
+  otherValue: "9"
+  testValue: "2"
+kind: ConfigMap
+metadata:
+  annotations: {}
+  labels: {}
+  name: comp-my-configmap-dgf97tmg6h
+---
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: comp-db
+spec:
+  type: Logical
+---
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: comp-stub
+spec:
+  replicas: 1
+`,
+		},
+		"nested-components": {
+			input: []FileGen{writeTestBase, writeTestComponent, writeDB,
+				writeC("/app/additionalcomp", `
+components:
+- ../comp
+configMapGenerator:
+- name: my-configmap
+  behavior: merge
+  literals:	
+    - otherValue=9
+`),
+				writeK("/app/prod", `
+resources:
+- ../base
+- db
+
+components:
+- ../additionalcomp
+`),
+			},
+			runPath: "/app/prod",
+			expectedOutput: `
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: comp-storefront
+spec:
+  replicas: 3
+---
+apiVersion: v1
+data:
+  compValue: "5"
+  otherValue: "9"
+  testValue: "2"
+kind: ConfigMap
+metadata:
+  annotations: {}
+  labels: {}
+  name: comp-my-configmap-dgf97tmg6h
+---
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: comp-db
+spec:
+  type: Logical
+---
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: comp-stub
+spec:
+  replicas: 1
+`,
+		},
+		// If a component sets a name prefix on a base, then that base can also be separately included
+		// without being affected by the component in another branch of the resource tree
+		"basic-component-with-repeated-base": {
+			input: []FileGen{writeTestBase, writeTestComponent, writeOverlayProd,
+				writeK("/app/repeated", `
+resources:
+- ../base
+- ../prod
+`),
+			},
+			runPath: "/app/repeated",
+			expectedOutput: `
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: storefront
+spec:
+  replicas: 1
+---
+apiVersion: v1
+data:
+  otherValue: "10"
+  testValue: "1"
+kind: ConfigMap
+metadata:
+  name: my-configmap-7k9t4h74f8
+---
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: comp-storefront
+spec:
+  replicas: 3
+---
+apiVersion: v1
+data:
+  compValue: "5"
+  otherValue: "10"
+  testValue: "2"
+kind: ConfigMap
+metadata:
+  annotations: {}
+  labels: {}
+  name: comp-my-configmap-ct5bgtbccd
+---
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: comp-db
+spec:
+  type: Logical
+---
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: comp-stub
+spec:
+  replicas: 1
+`,
+		},
+		"applying-component-directly-should-be-same-as-kustomization": {
+			input: []FileGen{writeTestBase, writeTestComponent,
+				writeC("/app/direct-component", `
+resources:
+- ../base
+configMapGenerator:
+- name: my-configmap
+  behavior: merge
+  literals:	
+    - compValue=5
+    - testValue=2
+`),
+			},
+			runPath: "/app/direct-component",
+			expectedOutput: `
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: storefront
+spec:
+  replicas: 1
+---
+apiVersion: v1
+data:
+  compValue: "5"
+  otherValue: "10"
+  testValue: "2"
+kind: ConfigMap
+metadata:
+  annotations: {}
+  labels: {}
+  name: my-configmap-96dt22k28h
+`,
+		},
+		"missing-optional-component-api-version": {
+			input: []FileGen{writeTestBase, writeOverlayProd,
+				writeF("/app/comp/"+konfig.DefaultKustomizationFileName(), `
+kind: Component
+configMapGenerator:
+- name: my-configmap
+  behavior: merge
+  literals:	
+    - otherValue=9
+`),
+			},
+			runPath: "/app/prod",
+			expectedOutput: `
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: storefront
+spec:
+  replicas: 1
+---
+apiVersion: v1
+data:
+  otherValue: "9"
+  testValue: "1"
+kind: ConfigMap
+metadata:
+  annotations: {}
+  labels: {}
+  name: my-configmap-72cfg2mg5d
+---
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: db
+spec:
+  type: Logical
+`,
+		},
+		// See how nameSuffix "-b" is also added to the resources included by "comp-a" because they are in the
+		// accumulator when "comp-b" is accumulated.  In practice we could use simple Kustomizations for this example.
+		"components-can-add-the-same-base-if-the-first-renames-resources": {
+			input: []FileGen{writeTestBase,
+				deployment("proxy", "/app/comp-a/proxy.yaml"),
+				writeC("/app/comp-a", `
+resources:
+- ../base
+
+nameSuffix: "-a"
+`),
+				writeC("/app/comp-b", `
+resources:
+- ../base
+
+nameSuffix: "-b"
+`),
+				writeK("/app/prod", `
+components:
+- ../comp-a
+- ../comp-b`),
+			},
+			runPath: "/app/prod",
+			expectedOutput: `
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: storefront-a-b
+spec:
+  replicas: 1
+---
+apiVersion: v1
+data:
+  otherValue: "10"
+  testValue: "1"
+kind: ConfigMap
+metadata:
+  name: my-configmap-a-b-tfb7c5t69m
+---
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: storefront-b
+spec:
+  replicas: 1
+---
+apiVersion: v1
+data:
+  otherValue: "10"
+  testValue: "1"
+kind: ConfigMap
+metadata:
+  name: my-configmap-b-8h7b8862bb
+`,
+		},
+
+		"multiple-bases-can-add-the-same-component-if-it-doesn-not-define-named-entities": {
+			input: []FileGen{
+				writeC("/app/comp", `
+namespace: prod
+`),
+				writeK("/app/base-a", `
+resources:
+- proxy.yaml
+
+components:
+- ../comp
+`),
+				deployment("proxy-a", "/app/base-a/proxy.yaml"),
+				writeK("/app/base-b", `
+resources:
+- proxy.yaml
+
+components:
+- ../comp
+`),
+				deployment("proxy-b", "/app/base-b/proxy.yaml"),
+				writeK("/app/prod", `
+resources:
+- proxy.yaml
+- ../base-a
+- ../base-b
+`),
+				deployment("proxy-prod", "/app/prod/proxy.yaml"),
+			},
+			runPath: "/app/prod",
+			// Note that the namepsace has not been applied to proxy-prod because it was not in scope when the
+			// component was applied
+			expectedOutput: `
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: proxy-prod
+spec:
+  type: Logical
+---
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: proxy-a
+  namespace: prod
+spec:
+  type: Logical
+---
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: proxy-b
+  namespace: prod
+spec:
+  type: Logical
+`,
+		},
+	}
+
+	for tn, tc := range testCases {
+		t.Run(tn, func(t *testing.T) {
+			th := kusttest_test.MakeHarness(t)
+			for _, f := range tc.input {
+				f(th)
+			}
+			m := th.Run(tc.runPath, th.MakeDefaultOptions())
+			th.AssertActualEqualsExpected(m, tc.expectedOutput)
+		})
+	}
+}
+
+func TestComponentErrors(t *testing.T) {
+	testCases := map[string]struct {
+		input         []FileGen
+		runPath       string
+		expectedError string
+	}{
+		"components-cannot-be-added-to-resources": {
+			input: []FileGen{writeTestBase, writeTestComponent,
+				writeK("/app/compinres", `
+resources:
+- ../base
+- ../comp
+`),
+			},
+			runPath:       "app/compinres",
+			expectedError: "expected kind != 'Component' for path '/app/comp'",
+		},
+		"kustomizations-cannot-be-added-to-components": {
+			input: []FileGen{writeTestBase, writeTestComponent,
+				writeK("/app/kustincomponents", `
+components:
+- ../base
+- ../comp
+`),
+			},
+			runPath: "/app/kustincomponents",
+			expectedError: "accumulating components: accumulateDirectory: \"expected kind 'Component' for path " +
+				"'/app/base' but got 'Kustomization'",
+		},
+		"files-cannot-be-added-to-components-list": {
+			input: []FileGen{writeTestBase,
+				writeF("/app/filesincomponents/stub.yaml", `
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: stub
+spec:
+  replicas: 1
+`),
+				writeK("/app/filesincomponents", `
+components:
+- stub.yaml
+- ../comp
+`),
+			},
+			runPath:       "/app/filesincomponents",
+			expectedError: "'/app/filesincomponents/stub.yaml' must be a directory to be a root",
+		},
+		"invalid-component-api-version": {
+			input: []FileGen{writeTestBase, writeOverlayProd,
+				writeF("/app/comp/"+konfig.DefaultKustomizationFileName(), `
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Component
+configMapGenerator:
+- name: my-configmap
+  behavior: merge
+  literals:	
+    - otherValue=9
+`),
+			},
+			runPath:       "/app/prod",
+			expectedError: "apiVersion for Component should be kustomize.config.k8s.io/v1alpha1",
+		},
+		"components-cannot-add-the-same-resource": {
+			input: []FileGen{writeTestBase,
+				writeC("/app/comp-a", `
+resources:
+- proxy.yaml
+`),
+				deployment("proxy", "/app/comp-a/proxy.yaml"),
+				writeC("/app/comp-b", `
+resources:
+- proxy.yaml
+`),
+				deployment("proxy", "/app/comp-b/proxy.yaml"),
+				writeK("/app/prod", `
+resources:
+- ../base
+
+components:
+- ../comp-a
+- ../comp-b`),
+			},
+			runPath:       "/app/prod",
+			expectedError: "may not add resource with an already registered id: ~G_v1_Deployment|~X|proxy",
+		},
+		"components-cannot-add-the-same-base": {
+			input: []FileGen{writeTestBase,
+				deployment("proxy", "/app/comp-a/proxy.yaml"),
+				writeC("/app/comp-a", `
+resources:
+- ../base
+`),
+				writeC("/app/comp-b", `
+resources:
+- ../base
+`),
+				writeK("/app/prod", `
+components:
+- ../comp-a
+- ../comp-b`),
+			},
+			runPath:       "/app/prod",
+			expectedError: "may not add resource with an already registered id: ~G_v1_Deployment|~X|storefront",
+		},
+		"components-cannot-add-bases-containing-the-same-resource": {
+			input: []FileGen{writeTestBase,
+				writeC("/app/comp-a", `
+resources:
+- ../base-a
+`),
+				writeK("/app/base-a", `
+resources:
+- proxy.yaml
+`),
+				deployment("proxy", "/app/base-a/proxy.yaml"),
+				writeC("/app/comp-b", `
+resources:
+- ../base-b
+`),
+				writeK("/app/base-b", `
+resources:
+- proxy.yaml
+`),
+				deployment("proxy", "/app/base-b/proxy.yaml"),
+				writeK("/app/prod", `
+resources:
+- ../base
+
+components:
+- ../comp-a
+- ../comp-b`),
+			},
+			runPath:       "/app/prod",
+			expectedError: "may not add resource with an already registered id: ~G_v1_Deployment|~X|proxy",
+		},
+	}
+
+	for tn, tc := range testCases {
+		t.Run(tn, func(t *testing.T) {
+			th := kusttest_test.MakeHarness(t)
+			for _, f := range tc.input {
+				f(th)
+			}
+			err := th.RunWithErr(tc.runPath, th.MakeDefaultOptions())
+			if err == nil || !strings.Contains(err.Error(), tc.expectedError) {
+				t.Fatalf("unexpected error: %s", err)
+			}
+		})
+	}
+}

api/testutils/kusttest/harness.go

@@ -52,6 +52,16 @@ kind: Kustomization
 `+content))
 }
 
+func (th Harness) WriteC(path string, content string) {
+	th.fSys.WriteFile(
+		filepath.Join(
+			path,
+			konfig.DefaultKustomizationFileName()), []byte(`
+apiVersion: kustomize.config.k8s.io/v1alpha1
+kind: Component
+`+content))
+}
+
 func (th Harness) WriteF(path string, content string) {
 	th.fSys.WriteFile(path, []byte(content))
 }

api/types/kustomization.go

@@ -6,6 +6,8 @@ package types
 const (
 	KustomizationVersion  = "kustomize.config.k8s.io/v1beta1"
 	KustomizationKind     = "Kustomization"
+	ComponentVersion      = "kustomize.config.k8s.io/v1alpha1"
+	ComponentKind         = "Component"
 	MetadataNamespacePath = "metadata/namespace"
 )
 
@@ -73,10 +75,14 @@ type Kustomization struct {
 	//
 
 	// Resources specifies relative paths to files holding YAML representations
-	// of kubernetes API objects, or specifcations of other kustomizations
+	// of kubernetes API objects, or specifications of other kustomizations
 	// via relative paths, absolute paths, or URLs.
 	Resources []string `json:"resources,omitempty" yaml:"resources,omitempty"`
 
+	// Components specifies relative paths to specifications of other Components
+	// via relative paths, absolute paths, or URLs.
+	Components []string `json:"components,omitempty" yaml:"components,omitempty"`
+
 	// Crds specifies relative paths to Custom Resource Definition files.
 	// This allows custom resources to be recognized as operands, making
 	// it possible to add them to the Resources list.
@@ -128,23 +134,31 @@ type Kustomization struct {
 // moving content of deprecated fields to newer
 // fields.
 func (k *Kustomization) FixKustomizationPostUnmarshalling() {
-	if k.APIVersion == "" {
-		k.APIVersion = KustomizationVersion
-	}
 	if k.Kind == "" {
 		k.Kind = KustomizationKind
 	}
+	if k.APIVersion == "" {
+		if k.Kind == ComponentKind {
+			k.APIVersion = ComponentVersion
+		} else {
+			k.APIVersion = KustomizationVersion
+		}
+	}
 	k.Resources = append(k.Resources, k.Bases...)
 	k.Bases = nil
 }
 
 func (k *Kustomization) EnforceFields() []string {
 	var errs []string
-	if k.APIVersion != "" && k.APIVersion != KustomizationVersion {
-		errs = append(errs, "apiVersion should be "+KustomizationVersion)
+	if k.Kind != "" && k.Kind != KustomizationKind && k.Kind != ComponentKind {
+		errs = append(errs, "kind should be "+KustomizationKind+" or "+ComponentKind)
 	}
-	if k.Kind != "" && k.Kind != KustomizationKind {
-		errs = append(errs, "kind should be "+KustomizationKind)
+	requiredVersion := KustomizationVersion
+	if k.Kind == ComponentKind {
+		requiredVersion = ComponentVersion
+	}
+	if k.APIVersion != "" && k.APIVersion != requiredVersion {
+		errs = append(errs, "apiVersion for "+k.Kind+" should be "+requiredVersion)
 	}
 	return errs
 }