Merge pull request #81910 from fabriziopandini/kubeadm-Json6902-Patches

kubeadm: add support for Json6902 Patches

cmd/kubeadm/app/util/kustomize/BUILD

@@ -3,21 +3,25 @@ load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 go_library(
     name = "go_default_library",
     srcs = [
+        "json6902.go",
         "kustomize.go",
-        "unstructured.go",
+        "strategicmerge.go",
     ],
     importpath = "k8s.io/kubernetes/cmd/kubeadm/app/util/kustomize",
     visibility = ["//visibility:public"],
     deps = [
         "//staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/unstructured:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/runtime:go_default_library",
-        "//staging/src/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/yaml:go_default_library",
         "//staging/src/k8s.io/cli-runtime/pkg/kustomize:go_default_library",
         "//vendor/github.com/pkg/errors:go_default_library",
+        "//vendor/sigs.k8s.io/kustomize/pkg/constants:go_default_library",
         "//vendor/sigs.k8s.io/kustomize/pkg/fs:go_default_library",
         "//vendor/sigs.k8s.io/kustomize/pkg/ifc:go_default_library",
         "//vendor/sigs.k8s.io/kustomize/pkg/loader:go_default_library",
+        "//vendor/sigs.k8s.io/kustomize/pkg/patch:go_default_library",
+        "//vendor/sigs.k8s.io/kustomize/pkg/types:go_default_library",
+        "//vendor/sigs.k8s.io/yaml:go_default_library",
     ],
 )
 
@@ -39,10 +43,11 @@ go_test(
     name = "go_default_test",
     srcs = [
         "kustomize_test.go",
-        "unstructured_test.go",
+        "strategicmerge_test.go",
     ],
     embed = [":go_default_library"],
     deps = [
+        "//staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/unstructured:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
         "//vendor/github.com/lithammer/dedent:go_default_library",
     ],

cmd/kubeadm/app/util/kustomize/json6902.go

@@ -0,0 +1,64 @@
+/*
+Copyright 2019 The Kubernetes 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 kustomize contains helpers for working with embedded kustomize commands
+package kustomize
+
+import (
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	"sigs.k8s.io/kustomize/pkg/ifc"
+	"sigs.k8s.io/kustomize/pkg/patch"
+)
+
+// json6902 represents a json6902 patch
+type json6902 struct {
+	// Target refers to a Kubernetes object that the json patch will be applied to
+	*patch.Target
+
+	// Patch contain the json patch as a string
+	Patch string
+}
+
+// json6902Slice is a slice of json6902 patches.
+type json6902Slice []*json6902
+
+// newJSON6902FromFile returns a json6902 patch from a file
+func newJSON6902FromFile(f patch.Json6902, ldr ifc.Loader, file string) (*json6902, error) {
+	patch, err := ldr.Load(file)
+	if err != nil {
+		return nil, err
+	}
+
+	return &json6902{
+		Target: f.Target,
+		Patch:  string(patch),
+	}, nil
+}
+
+// filterByResource returns all the json6902 patches in the json6902Slice corresponding to a given resource
+func (s *json6902Slice) filterByResource(r *unstructured.Unstructured) json6902Slice {
+	var result json6902Slice
+	for _, p := range *s {
+		if p.Group == r.GroupVersionKind().Group &&
+			p.Version == r.GroupVersionKind().Version &&
+			p.Kind == r.GroupVersionKind().Kind &&
+			p.Namespace == r.GetNamespace() &&
+			p.Name == r.GetName() {
+			result = append(result, p)
+		}
+	}
+	return result
+}

cmd/kubeadm/app/util/kustomize/kustomize.go

@@ -25,15 +25,25 @@ import (
 	"runtime"
 	"sync"
 
+	"github.com/pkg/errors"
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	yamlutil "k8s.io/apimachinery/pkg/util/yaml"
 	"k8s.io/cli-runtime/pkg/kustomize"
+	"sigs.k8s.io/kustomize/pkg/constants"
 	"sigs.k8s.io/kustomize/pkg/fs"
+	"sigs.k8s.io/kustomize/pkg/ifc"
 	"sigs.k8s.io/kustomize/pkg/loader"
+	"sigs.k8s.io/kustomize/pkg/patch"
+	"sigs.k8s.io/kustomize/pkg/types"
+	"sigs.k8s.io/yaml"
 )
 
 // Manager define a manager that allow access to kustomize capabilities
 type Manager struct {
 	kustomizeDir          string
-	us           UnstructuredSlice
+	kustomizationFile     *types.Kustomization
+	strategicMergePatches strategicMergeSlice
+	json6902Patches       json6902Slice
 }
 
 var (
@@ -42,6 +52,8 @@ var (
 )
 
 // GetManager return the KustomizeManager singleton instance
+// NB. this is done at singleton instance level because kubeadm has a unique pool
+// of patches that are applied to different content, at different time
 func GetManager(kustomizeDir string) (*Manager, error) {
 	lock.Lock()
 	defer lock.Unlock()
@@ -52,12 +64,31 @@ func GetManager(kustomizeDir string) (*Manager, error) {
 			kustomizeDir: kustomizeDir,
 		}
 
-		// loads the UnstructuredSlice with all the patches into the Manager
-		// NB. this is done at singleton instance level because kubeadm has a unique pool
-		// of patches that are applied to different content, at different time
-		if err := km.getUnstructuredSlice(); err != nil {
+		// Create a loader that mimics the behavior of kubectl kustomize, including support for reading from
+		// a local folder or git repository like git@github.com:someOrg/someRepo.git or https://github.com/someOrg/someRepo?ref=someHash
+		// in order to do so you must use ldr.Root() instead of km.kustomizeDir and ldr.Load instead of other ways to read files
+		fSys := fs.MakeRealFS()
+		ldr, err := loader.NewLoader(km.kustomizeDir, fSys)
+		if err != nil {
 			return nil, err
 		}
+		defer ldr.Cleanup()
+
+		// read the Kustomization file and all the patches it is
+		// referencing (either stategicMerge or json6902 patches)
+		if err := km.loadFromKustomizationFile(ldr); err != nil {
+			return nil, err
+		}
+
+		// if a Kustomization file was not found, kubeadm creates
+		// one using all the patches in the folder; however in this
+		// case only stategicMerge patches are supported
+		if km.kustomizationFile == nil {
+			km.kustomizationFile = &types.Kustomization{}
+			if err := km.loadFromFolder(ldr); err != nil {
+				return nil, err
+			}
+		}
 
 		instances[kustomizeDir] = km
 	}
@@ -65,78 +96,103 @@ func GetManager(kustomizeDir string) (*Manager, error) {
 	return instances[kustomizeDir], nil
 }
 
-// getUnstructuredSlice returns a UnstructuredSlice with all the patches.
-func (km *Manager) getUnstructuredSlice() error {
-	// kubeadm does not require a kustomization.yaml file listing all the resources/patches, so it is necessary
-	// to rebuild the list of patches manually
-	// TODO: make this git friendly - currently this works only for patches in local folders -
-	files, err := ioutil.ReadDir(km.kustomizeDir)
+// loadFromKustomizationFile reads a Kustomization file and all the patches it is
+// referencing (either stategicMerge or json6902 patches)
+func (km *Manager) loadFromKustomizationFile(ldr ifc.Loader) error {
+	// Kustomize support different KustomizationFileNames, so we try to read all
+	var content []byte
+	match := 0
+	for _, kf := range constants.KustomizationFileNames {
+		c, err := ldr.Load(kf)
+		if err == nil {
+			match++
+			content = c
+		}
+	}
+
+	// if no kustomization file is found return
+	if match == 0 {
+		return nil
+	}
+
+	// if more that one kustomization file is found, return error
+	if match > 1 {
+		return errors.Errorf("Found multiple kustomization files under: %s\n", ldr.Root())
+	}
+
+	// Decode the kustomization file
+	decoder := yamlutil.NewYAMLOrJSONDecoder(bytes.NewReader(content), 1024)
+	var k = &types.Kustomization{}
+	if err := decoder.Decode(k); err != nil {
+		return errors.Wrap(err, "Error decoding kustomization file")
+	}
+	km.kustomizationFile = k
+
+	// gets all the strategic merge patches
+	for _, f := range km.kustomizationFile.PatchesStrategicMerge {
+		smp, err := newStrategicMergeSliceFromFile(ldr, string(f))
 		if err != nil {
 			return err
 		}
+		km.strategicMergePatches = append(km.strategicMergePatches, smp...)
+	}
 
-	var paths = []string{}
-	for _, file := range files {
-		if file.IsDir() {
+	// gets all the json6902 patches
+	for _, f := range km.kustomizationFile.PatchesJson6902 {
+		jp, err := newJSON6902FromFile(f, ldr, f.Path)
+		if err != nil {
+			return err
+		}
+		km.json6902Patches = append(km.json6902Patches, jp)
+	}
+
+	return nil
+}
+
+// loadFromFolder returns all the stategicMerge patches in a folder
+func (km *Manager) loadFromFolder(ldr ifc.Loader) error {
+	files, err := ioutil.ReadDir(ldr.Root())
+	if err != nil {
+		return err
+	}
+	for _, fileInfo := range files {
+		if fileInfo.IsDir() {
 			continue
 		}
-		paths = append(paths, file.Name())
-	}
 
-	// Create a loader that mimics the behavior of kubectl kustomize, including support for reading from
-	// a local git repository like git@github.com:someOrg/someRepo.git or https://github.com/someOrg/someRepo?ref=someHash
-	fSys := fs.MakeRealFS()
-	ldr, err := loader.NewLoader(km.kustomizeDir, fSys)
+		smp, err := newStrategicMergeSliceFromFile(ldr, fileInfo.Name())
 		if err != nil {
 			return err
 		}
-	defer ldr.Cleanup()
-
-	// read all the kustomizations and build the UnstructuredSlice
-	us, err := NewUnstructuredSliceFromFiles(ldr, paths)
-	if err != nil {
-		return err
+		km.strategicMergePatches = append(km.strategicMergePatches, smp...)
 	}
-
-	km.us = us
 	return nil
 }
 
 // Kustomize apply a set of patches to a resource.
 // Portions of the kustomize logic in this function are taken from the kubernetes-sigs/kind project
-func (km *Manager) Kustomize(res []byte) ([]byte, error) {
-	// create a loader that mimics the behavior of kubectl kustomize
-	// and converts the resource into a UnstructuredSlice
-	// Nb. in kubeadm we are controlling resource generation, and so we
-	// we are expecting 1 object into each resource, eg. the static pod.
-	// Nevertheless, this code is ready for more than one object per resource
-	resList, err := NewUnstructuredSliceFromBytes(res)
-	if err != nil {
+func (km *Manager) Kustomize(data []byte) ([]byte, error) {
+	// parse the resource to kustomize
+	decoder := yamlutil.NewYAMLOrJSONDecoder(bytes.NewReader(data), 1024)
+	var resource *unstructured.Unstructured
+	if err := decoder.Decode(&resource); err != nil {
 		return nil, err
 	}
 
-	// create a list of resource and corresponding patches
-	var resources, patches UnstructuredSlice
-	for _, r := range resList {
-		resources = append(resources, r)
-
-		resourcePatches := km.us.FilterResource(r.GroupVersionKind(), r.GetNamespace(), r.GetName())
-
-		if len(resourcePatches) > 0 {
-			fmt.Printf("[kustomize] Applying %d patches to %s Resource=%s/%s\n", len(resourcePatches), r.GroupVersionKind(), r.GetNamespace(), r.GetName())
-			patches = append(patches, resourcePatches...)
-		}
-	}
+	// get patches corresponding to this resource
+	strategicMerge := km.strategicMergePatches.filterByResource(resource)
+	json6902 := km.json6902Patches.filterByResource(resource)
 
 	// if there are no patches, for the target resources, exit
-	if len(patches) == 0 {
-		return res, nil
+	if len(strategicMerge)+len(json6902) == 0 {
+		return data, nil
 	}
 
+	fmt.Printf("[kustomize] Applying %d patches to %s Resource=%s/%s\n", len(strategicMerge)+len(json6902), resource.GroupVersionKind(), resource.GetNamespace(), resource.GetName())
+
 	// create an in memory fs to use for the kustomization
 	memFS := fs.MakeFakeFS()
 
-	var kustomization bytes.Buffer
 	fakeDir := "/"
 	// for Windows we need this to be a drive because kustomize uses filepath.Abs()
 	// which will add a drive letter if there is none. which drive letter is
@@ -145,33 +201,44 @@ func (km *Manager) Kustomize(res []byte) ([]byte, error) {
 		fakeDir = `C:\`
 	}
 
-	// write resources and patches to the in memory fs, generate the kustomization.yaml
-	// that ties everything together
-	kustomization.WriteString("resources:\n")
-	for i, r := range resources {
-		b, err := r.MarshalJSON()
+	// writes the resource to a file in the temp file system
+	b, err := yaml.Marshal(resource)
 	if err != nil {
 		return nil, err
 	}
-
-		name := fmt.Sprintf("resource-%d.json", i)
+	name := "resource.yaml"
 	_ = memFS.WriteFile(filepath.Join(fakeDir, name), b)
-		fmt.Fprintf(&kustomization, " - %s\n", name)
-	}
 
-	kustomization.WriteString("patches:\n")
-	for i, p := range patches {
-		b, err := p.MarshalJSON()
+	km.kustomizationFile.Resources = []string{name}
+
+	// writes strategic merge patches to files in the temp file system
+	km.kustomizationFile.PatchesStrategicMerge = []patch.StrategicMerge{}
+	for i, p := range strategicMerge {
+		b, err := yaml.Marshal(p)
 		if err != nil {
 			return nil, err
 		}
-
-		name := fmt.Sprintf("patch-%d.json", i)
+		name := fmt.Sprintf("patch-%d.yaml", i)
 		_ = memFS.WriteFile(filepath.Join(fakeDir, name), b)
-		fmt.Fprintf(&kustomization, " - %s\n", name)
+
+		km.kustomizationFile.PatchesStrategicMerge = append(km.kustomizationFile.PatchesStrategicMerge, patch.StrategicMerge(name))
 	}
 
-	memFS.WriteFile(filepath.Join(fakeDir, "kustomization.yaml"), kustomization.Bytes())
+	// writes json6902 patches to files in the temp file system
+	km.kustomizationFile.PatchesJson6902 = []patch.Json6902{}
+	for i, p := range json6902 {
+		name := fmt.Sprintf("patchjson-%d.yaml", i)
+		_ = memFS.WriteFile(filepath.Join(fakeDir, name), []byte(p.Patch))
+
+		km.kustomizationFile.PatchesJson6902 = append(km.kustomizationFile.PatchesJson6902, patch.Json6902{Target: p.Target, Path: name})
+	}
+
+	// writes the kustomization file to the temp file system
+	kbytes, err := yaml.Marshal(km.kustomizationFile)
+	if err != nil {
+		return nil, err
+	}
+	memFS.WriteFile(filepath.Join(fakeDir, "kustomization.yaml"), kbytes)
 
 	// Finally customize the target resource
 	var out bytes.Buffer

cmd/kubeadm/app/util/kustomize/kustomize_test.go

@@ -26,21 +26,14 @@ import (
 	"github.com/lithammer/dedent"
 )
 
-func TestKustomize(t *testing.T) {
+func TestKustomizeWithoutKustomizationFile(t *testing.T) {
 	tmpdir, err := ioutil.TempDir("", "")
 	if err != nil {
 		t.Fatal("Couldn't create tmpdir")
 	}
 	defer os.RemoveAll(tmpdir)
 
-	resourceString := dedent.Dedent(`
-    apiVersion: v1
-    kind: Pod
-    metadata:
-        name: kube-apiserver
-    `)
-
-	patch1String := dedent.Dedent(`
+	strategicMergePatch1 := dedent.Dedent(`
     apiVersion: v1
     kind: Pod
     metadata:
@@ -49,12 +42,12 @@ func TestKustomize(t *testing.T) {
             kustomize: patch for kube-apiserver
     `)
 
-	err = ioutil.WriteFile(filepath.Join(tmpdir, "patch-1.yaml"), []byte(patch1String), 0644)
+	err = ioutil.WriteFile(filepath.Join(tmpdir, "patch-1.yaml"), []byte(strategicMergePatch1), 0644)
 	if err != nil {
 		t.Fatalf("WriteFile returned unexpected error: %v", err)
 	}
 
-	patch2String := dedent.Dedent(`
+	strategicMergePatch2 := dedent.Dedent(`
     apiVersion: v1
     kind: Pod
     metadata:
@@ -63,26 +56,148 @@ func TestKustomize(t *testing.T) {
             kustomize: patch for kube-scheduler
     `)
 
-	err = ioutil.WriteFile(filepath.Join(tmpdir, "patch-2.yaml"), []byte(patch2String), 0644)
+	err = ioutil.WriteFile(filepath.Join(tmpdir, "patch-2.yaml"), []byte(strategicMergePatch2), 0644)
 	if err != nil {
 		t.Fatalf("WriteFile returned unexpected error: %v", err)
 	}
 
 	km, err := GetManager(tmpdir)
 	if err != nil {
-		t.Errorf("GetManager returned unexpected error: %v", err)
+		t.Fatalf("GetManager returned unexpected error: %v", err)
 	}
 
-	kustomized, err := km.Kustomize([]byte(resourceString))
+	resource := dedent.Dedent(`
+    apiVersion: v1
+    kind: Pod
+    metadata:
+        name: kube-apiserver
+    `)
+
+	kustomized, err := km.Kustomize([]byte(resource))
 	if err != nil {
-		t.Errorf("Kustomize returned unexpected error: %v", err)
+		t.Fatalf("Kustomize returned unexpected error: %v", err)
 	}
 
 	if !strings.Contains(string(kustomized), "kustomize: patch for kube-apiserver") {
-		t.Error("Kustomize did not apply patches corresponding to the resource")
+		t.Error("Kustomize did not apply strategicMergePatch")
 	}
 
 	if strings.Contains(string(kustomized), "kustomize: patch for kube-scheduler") {
 		t.Error("Kustomize did apply patches not corresponding to the resource")
 	}
 }
+
+func TestKustomizeWithKustomizationFile(t *testing.T) {
+	tmpdir, err := ioutil.TempDir("", "")
+	if err != nil {
+		t.Fatal("Couldn't create tmpdir")
+	}
+	defer os.RemoveAll(tmpdir)
+
+	kustomizationFile := dedent.Dedent(`
+    patchesJson6902:
+    - target:
+        version: v1
+        kind: Pod
+        name: kube-apiserver
+      path: patch-1.yaml
+    - target:
+        version: v1
+        kind: Pod
+        name: kube-scheduler
+      path: patch-2.yaml
+    patchesStrategicMerge:
+    - patch-3.yaml
+    - patch-4.yaml
+    `)
+
+	err = ioutil.WriteFile(filepath.Join(tmpdir, "kustomization.yaml"), []byte(kustomizationFile), 0644)
+	if err != nil {
+		t.Fatalf("WriteFile returned unexpected error: %v", err)
+	}
+
+	jsonPatch1 := dedent.Dedent(`
+    - op: add
+      path: "/metadata/labels"
+      value: 
+          kustomize1: patch for kube-apiserver
+    `)
+
+	err = ioutil.WriteFile(filepath.Join(tmpdir, "patch-1.yaml"), []byte(jsonPatch1), 0644)
+	if err != nil {
+		t.Fatalf("WriteFile returned unexpected error: %v", err)
+	}
+
+	jsonPatch2 := dedent.Dedent(`
+    - op: add
+      path: "/metadata/labels"
+      value:
+      kustomize1: patch for kube-scheduler	
+    `)
+
+	err = ioutil.WriteFile(filepath.Join(tmpdir, "patch-2.yaml"), []byte(jsonPatch2), 0644)
+	if err != nil {
+		t.Fatalf("WriteFile returned unexpected error: %v", err)
+	}
+
+	strategicMergePatch1 := dedent.Dedent(`
+    apiVersion: v1
+    kind: Pod
+    metadata:
+        name: kube-apiserver
+        annotations:
+            kustomize2: patch for kube-apiserver
+    `)
+
+	err = ioutil.WriteFile(filepath.Join(tmpdir, "patch-3.yaml"), []byte(strategicMergePatch1), 0644)
+	if err != nil {
+		t.Fatalf("WriteFile returned unexpected error: %v", err)
+	}
+
+	strategicMergePatch2 := dedent.Dedent(`
+    apiVersion: v1
+    kind: Pod
+    metadata:
+        name: kube-scheduler
+        annotations:
+            kustomize2: patch for kube-scheduler
+    `)
+
+	err = ioutil.WriteFile(filepath.Join(tmpdir, "patch-4.yaml"), []byte(strategicMergePatch2), 0644)
+	if err != nil {
+		t.Fatalf("WriteFile returned unexpected error: %v", err)
+	}
+
+	km, err := GetManager(tmpdir)
+	if err != nil {
+		t.Fatalf("GetManager returned unexpected error: %v", err)
+	}
+
+	resource := dedent.Dedent(`
+    apiVersion: v1
+    kind: Pod
+    metadata:
+        name: kube-apiserver
+    `)
+
+	kustomized, err := km.Kustomize([]byte(resource))
+	if err != nil {
+		t.Fatalf("Kustomize returned unexpected error: %v", err)
+	}
+
+	if !strings.Contains(string(kustomized), "kustomize1: patch for kube-apiserver") {
+		t.Error("Kustomize did not apply json patches corresponding to the resource")
+	}
+
+	if strings.Contains(string(kustomized), "kustomize1: patch for kube-scheduler") {
+		t.Error("Kustomize did apply json patches not corresponding to the resource")
+	}
+
+	if !strings.Contains(string(kustomized), "kustomize2: patch for kube-apiserver") {
+		t.Error("Kustomize did not apply strategic merge patches corresponding to the resource")
+	}
+
+	if strings.Contains(string(kustomized), "kustomize2: patch for kube-scheduler") {
+		t.Error("Kustomize did apply strategic merge patches not corresponding to the resource")
+	}
+}

cmd/kubeadm/app/util/kustomize/strategicmerge.go

@@ -26,41 +26,33 @@ import (
 
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime"
-	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/util/yaml"
 	"sigs.k8s.io/kustomize/pkg/ifc"
 )
 
-// UnstructuredSlice is a slice of Unstructured objects.
-// Unstructured objects are used to represent both resources and patches of any group/version/kind.
-type UnstructuredSlice []*unstructured.Unstructured
+// strategicMergeSlice is a slice of strategic merge patches.
+// Unstructured objects are used to represent strategic merge patches of any group/version/kind.
+type strategicMergeSlice []*unstructured.Unstructured
 
-// NewUnstructuredSliceFromFiles returns a ResMap given a resource path slice.
-// This func use a Loader to mimic the behavior of kubectl kustomize, and most specifically support for reading from
-// a local git repository like git@github.com:someOrg/someRepo.git or https://github.com/someOrg/someRepo?ref=someHash
-func NewUnstructuredSliceFromFiles(loader ifc.Loader, paths []string) (UnstructuredSlice, error) {
-	var result UnstructuredSlice
-	for _, path := range paths {
+// newStrategicMergeSliceFromFile returns a slice of strategic merge patches from a file
+func newStrategicMergeSliceFromFile(loader ifc.Loader, path string) (strategicMergeSlice, error) {
 	content, err := loader.Load(path)
 	if err != nil {
 		return nil, errors.Wrapf(err, "load from path %q failed", path)
 	}
-		res, err := NewUnstructuredSliceFromBytes(content)
+	res, err := newStrategicMergeSliceFromBytes(content)
 	if err != nil {
 		return nil, errors.Wrapf(err, "convert %q to Unstructured failed", path)
 	}
-
-		result = append(result, res...)
-	}
-	return result, nil
+	return res, nil
 }
 
-// NewUnstructuredSliceFromBytes returns a slice of Unstructured.
+// newStrategicMergeSliceFromBytes returns a strategic merge patches contained in a []byte.
 // This functions handles all the nuances of Kubernetes yaml (e.g. many yaml
 // documents in one file, List of objects)
-func NewUnstructuredSliceFromBytes(in []byte) (UnstructuredSlice, error) {
+func newStrategicMergeSliceFromBytes(in []byte) (strategicMergeSlice, error) {
 	decoder := yaml.NewYAMLOrJSONDecoder(bytes.NewReader(in), 1024)
-	var result UnstructuredSlice
+	var result strategicMergeSlice
 	var err error
 	// Parse all the yaml documents in the file
 	for err == nil || isEmptyYamlError(err) {
@@ -88,13 +80,13 @@ func NewUnstructuredSliceFromBytes(in []byte) (UnstructuredSlice, error) {
 						return err
 					}
 
-					// Get the UnstructuredSlice for the item
-					itemU, err := NewUnstructuredSliceFromBytes(itemJSON)
+					// Get the stategicMergeSlice for the item
+					itemU, err := newStrategicMergeSliceFromBytes(itemJSON)
 					if err != nil {
 						return err
 					}
 
-					// append the UnstructuredSlice for the item to the UnstructuredSlice
+					// append the stategicMergeSlice for the item to the stategicMergeSlice
 					result = append(result, itemU...)
 
 					return nil
@@ -105,7 +97,7 @@ func NewUnstructuredSliceFromBytes(in []byte) (UnstructuredSlice, error) {
 				continue
 			}
 
-			// append the object to the UnstructuredSlice
+			// append the object to the stategicMergeSlice
 			result = append(result, &u)
 		}
 	}
@@ -115,14 +107,14 @@ func NewUnstructuredSliceFromBytes(in []byte) (UnstructuredSlice, error) {
 	return result, nil
 }
 
-// FilterResource returns all the Unstructured items in the UnstructuredSlice corresponding to a given resource
-func (rs *UnstructuredSlice) FilterResource(gvk schema.GroupVersionKind, namespace, name string) UnstructuredSlice {
-	var result UnstructuredSlice
-	for _, r := range *rs {
-		if r.GroupVersionKind() == gvk &&
-			r.GetNamespace() == namespace &&
-			r.GetName() == name {
-			result = append(result, r)
+// filterByResource returns all the strategic merge patches in the strategicMergeSlice corresponding to a given resource
+func (s *strategicMergeSlice) filterByResource(r *unstructured.Unstructured) strategicMergeSlice {
+	var result strategicMergeSlice
+	for _, p := range *s {
+		if p.GroupVersionKind() == r.GroupVersionKind() &&
+			p.GetNamespace() == r.GetNamespace() &&
+			p.GetName() == r.GetName() {
+			result = append(result, p)
 		}
 	}
 	return result

cmd/kubeadm/app/util/kustomize/strategicmerge_test.go

@@ -20,20 +20,21 @@ import (
 	"testing"
 
 	"github.com/lithammer/dedent"
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 )
 
-func TestNewUnstructuredSliceFromBytes(t *testing.T) {
+func TestNewStategicMergeSliceFromBytes(t *testing.T) {
 	var useCases = []struct {
 		name            string
 		in              string
-		expectedUnctructured int
+		expectedPatches int
 		expectedError   bool
 	}{
 		{
 			name:            "empty",
 			in:              "",
-			expectedUnctructured: 0,
+			expectedPatches: 0,
 		},
 		{
 			name: "single patch",
@@ -43,7 +44,7 @@ func TestNewUnstructuredSliceFromBytes(t *testing.T) {
             metadata:
               name: kube-apiserver
             `),
-			expectedUnctructured: 1,
+			expectedPatches: 1,
 		},
 		{
 			name: "two patches as separated yaml documents",
@@ -58,7 +59,7 @@ func TestNewUnstructuredSliceFromBytes(t *testing.T) {
             metadata:
               name: kube-apiserver
             `),
-			expectedUnctructured: 2,
+			expectedPatches: 2,
 		},
 		{
 			name: "two patches as a k8s list",
@@ -75,7 +76,7 @@ func TestNewUnstructuredSliceFromBytes(t *testing.T) {
               metadata:
                 name: kube-apiserver
             `),
-			expectedUnctructured: 2,
+			expectedPatches: 2,
 		},
 		{
 			name: "nested k8s lists",
@@ -95,7 +96,7 @@ func TestNewUnstructuredSliceFromBytes(t *testing.T) {
                 metadata:
                   name: kube-apiserver
             `),
-			expectedUnctructured: 2,
+			expectedPatches: 2,
 		},
 		{
 			name:          "invalid yaml",
@@ -125,18 +126,18 @@ func TestNewUnstructuredSliceFromBytes(t *testing.T) {
 	}
 	for _, rt := range useCases {
 		t.Run(rt.name, func(t *testing.T) {
-			r, err := NewUnstructuredSliceFromBytes([]byte(rt.in))
+			r, err := newStrategicMergeSliceFromBytes([]byte(rt.in))
 			if err != nil {
 				if !rt.expectedError {
-					t.Errorf("NewUnstructuredSliceFromBytes returned unexpected error: %v", err)
+					t.Errorf("newStrategicMergeSliceFromBytes returned unexpected error: %v", err)
 				}
 				return
 			}
 			if err == nil && rt.expectedError {
-				t.Error("NewUnstructuredSliceFromBytes does not returned expected error")
+				t.Error("newStrategicMergeSliceFromBytes does not returned expected error")
 			}
-			if len(r) != rt.expectedUnctructured {
-				t.Errorf("Expected %d Unstructured items in the slice, actual %d", rt.expectedUnctructured, len(r))
+			if len(r) != rt.expectedPatches {
+				t.Errorf("Expected %d strategic merge patches in the slice, actual %d", rt.expectedPatches, len(r))
 			}
 		})
 	}
@@ -162,9 +163,9 @@ func TestFilterResource(t *testing.T) {
       name: kube-scheduler
       namespace: kube-system
     `)
-	u, err := NewUnstructuredSliceFromBytes([]byte(in))
+	u, err := newStrategicMergeSliceFromBytes([]byte(in))
 	if err != nil {
-		t.Fatalf("NewUnstructuredSliceFromBytes returned unexpected error: %v", err)
+		t.Fatalf("newStategicMergeSliceFromBytes returned unexpected error: %v", err)
 	}
 
 	var useCases = []struct {
@@ -172,50 +173,55 @@ func TestFilterResource(t *testing.T) {
 		rgvk            schema.GroupVersionKind
 		rnamespace      string
 		rname           string
-		expectedUnctructured int
+		expectedPatches int
 	}{
 		{
 			name:            "match 1",
 			rgvk:            schema.GroupVersionKind{Group: "", Version: "v1", Kind: "Pod"},
 			rnamespace:      "kube-system",
 			rname:           "kube-apiserver",
-			expectedUnctructured: 1,
+			expectedPatches: 1,
 		},
 		{
 			name:            "match 2",
 			rgvk:            schema.GroupVersionKind{Group: "", Version: "v1", Kind: "Pod"},
 			rnamespace:      "kube-system",
 			rname:           "kube-scheduler",
-			expectedUnctructured: 2,
+			expectedPatches: 2,
 		},
 		{
 			name:            "match 0 (wrong gvk)",
 			rgvk:            schema.GroupVersionKind{Group: "something", Version: "v1", Kind: "Pod"},
 			rnamespace:      "kube-system",
 			rname:           "kube-scheduler",
-			expectedUnctructured: 0,
+			expectedPatches: 0,
 		},
 		{
 			name:            "match 0 (wrong namespace)",
 			rgvk:            schema.GroupVersionKind{Group: "", Version: "v1", Kind: "Pod"},
 			rnamespace:      "kube-something",
 			rname:           "kube-scheduler",
-			expectedUnctructured: 0,
+			expectedPatches: 0,
 		},
 		{
 			name:            "match 0 (wrong namr)",
 			rgvk:            schema.GroupVersionKind{Group: "", Version: "v1", Kind: "Pod"},
 			rnamespace:      "kube-system",
 			rname:           "kube-something",
-			expectedUnctructured: 0,
+			expectedPatches: 0,
 		},
 	}
 	for _, rt := range useCases {
 		t.Run(rt.name, func(t *testing.T) {
-			r := u.FilterResource(rt.rgvk, rt.rnamespace, rt.rname)
+			resource := &unstructured.Unstructured{}
+			resource.SetGroupVersionKind(rt.rgvk)
+			resource.SetNamespace(rt.rnamespace)
+			resource.SetName(rt.rname)
 
-			if len(r) != rt.expectedUnctructured {
-				t.Errorf("Expected %d Unstructured items in the slice, actual %d", rt.expectedUnctructured, len(r))
+			r := u.filterByResource(resource)
+
+			if len(r) != rt.expectedPatches {
+				t.Errorf("Expected %d strategic merge patches in the slice, actual %d", rt.expectedPatches, len(r))
 			}
 		})
 	}