feat: Allow using kubectl built-in kustomize when separate kustomize binary is missing

kubectl_kustomize_test.go

@@ -0,0 +1,164 @@
+package chartify
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+// stubKubectlScript is a minimal sh script that acts as a kubectl stub for tests.
+// It handles `kubectl kustomize <dir> [-o|-o FILE|--output FILE]` by writing
+// a minimal valid Kubernetes Deployment YAML to the specified output file.
+const stubKubectlScript = `#!/bin/sh
+if [ "$1" = "kustomize" ]; then
+  shift
+  OUTPUT=""
+  while [ $# -gt 0 ]; do
+    case "$1" in
+      -o) OUTPUT="$2"; shift 2;;
+      --output) OUTPUT="$2"; shift 2;;
+      *) shift;;
+    esac
+  done
+  if [ -n "$OUTPUT" ]; then
+    printf 'apiVersion: apps/v1\nkind: Deployment\nmetadata:\n  name: stub\n' > "$OUTPUT"
+  fi
+fi
+`
+
+// writeStubKubectl creates a stub kubectl script in dir.
+func writeStubKubectl(t *testing.T, dir string) {
+	t.Helper()
+	p := filepath.Join(dir, "kubectl")
+	require.NoError(t, os.WriteFile(p, []byte(stubKubectlScript), 0755))
+}
+
+// TestKubectlKustomize tests behavior when kubectl kustomize is explicitly configured
+// via KustomizeBin("kubectl kustomize"). The automatic fallback selection is tested
+// in TestKustomizeBin.
+func TestKubectlKustomize(t *testing.T) {
+	t.Run("KustomizeBuild succeeds with kubectl kustomize option", func(t *testing.T) {
+		// Create a stub kubectl so the test is self-contained and always runs in CI.
+		stubDir := t.TempDir()
+		writeStubKubectl(t, stubDir)
+
+		origPath := os.Getenv("PATH")
+		defer os.Setenv("PATH", origPath)
+		os.Setenv("PATH", stubDir+string(os.PathListSeparator)+origPath)
+
+		tmpDir := t.TempDir()
+		srcDir := t.TempDir()
+
+		kustomizationContent := `apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+resources:
+- deployment.yaml
+`
+		deploymentContent := `apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: test
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: test
+  template:
+    metadata:
+      labels:
+        app: test
+    spec:
+      containers:
+      - name: test
+        image: test:latest
+`
+
+		templatesDir := filepath.Join(tmpDir, "templates")
+		require.NoError(t, os.MkdirAll(templatesDir, 0755))
+
+		require.NoError(t, os.WriteFile(filepath.Join(srcDir, "kustomization.yaml"), []byte(kustomizationContent), 0644))
+		require.NoError(t, os.WriteFile(filepath.Join(srcDir, "deployment.yaml"), []byte(deploymentContent), 0644))
+
+		r := New(KustomizeBin("kubectl kustomize"))
+
+		outputFile, err := r.KustomizeBuild(srcDir, tmpDir)
+		require.NoError(t, err)
+		require.FileExists(t, outputFile)
+	})
+
+	t.Run("Patch succeeds with kubectl kustomize option", func(t *testing.T) {
+		// Create a stub kubectl so the test is self-contained and always runs in CI.
+		stubDir := t.TempDir()
+		writeStubKubectl(t, stubDir)
+
+		origPath := os.Getenv("PATH")
+		defer os.Setenv("PATH", origPath)
+		os.Setenv("PATH", stubDir+string(os.PathListSeparator)+origPath)
+
+		tempDir := t.TempDir()
+
+		// Write a minimal manifest file that Patch() will reference.
+		manifestPath := filepath.Join(tempDir, "templates", "deploy.yaml")
+		require.NoError(t, os.MkdirAll(filepath.Dir(manifestPath), 0755))
+		require.NoError(t, os.WriteFile(manifestPath, []byte(`apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: test
+`), 0644))
+
+		r := New(KustomizeBin("kubectl kustomize"))
+		err := r.Patch(tempDir, []string{manifestPath}, &PatchOpts{})
+		require.NoError(t, err)
+	})
+
+	t.Run("edit commands not supported with kubectl kustomize", func(t *testing.T) {
+		tmpDir := t.TempDir()
+		srcDir := t.TempDir()
+
+		kustomizationContent := `apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+resources:
+- deployment.yaml
+`
+		deploymentContent := `apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: test
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: test
+  template:
+    metadata:
+      labels:
+        app: test
+    spec:
+      containers:
+      - name: test
+        image: test:latest
+`
+
+		templatesDir := filepath.Join(tmpDir, "templates")
+		valuesDir := t.TempDir()
+		valuesFile := filepath.Join(valuesDir, "values.yaml")
+		valuesContent := `images:
+- name: test
+  newName: newtest
+  newTag: v2
+`
+
+		require.NoError(t, os.MkdirAll(templatesDir, 0755))
+		require.NoError(t, os.WriteFile(filepath.Join(srcDir, "kustomization.yaml"), []byte(kustomizationContent), 0644))
+		require.NoError(t, os.WriteFile(filepath.Join(srcDir, "deployment.yaml"), []byte(deploymentContent), 0644))
+		require.NoError(t, os.WriteFile(valuesFile, []byte(valuesContent), 0644))
+
+		r := New(KustomizeBin("kubectl kustomize"))
+
+		_, err := r.KustomizeBuild(srcDir, tmpDir, &KustomizeBuildOpts{ValuesFiles: []string{valuesFile}})
+		require.Error(t, err)
+		require.Contains(t, err.Error(), "setting images via Chartify values files or kustomize build options is not supported when using 'kubectl kustomize'")
+	})
+}

kustomize.go

@@ -84,6 +84,10 @@ func (r *Runner) KustomizeBuild(srcDir string, tempDir string, opts ...Kustomize
 		panic("--set is not yet supported for kustomize-based apps! Use -f/--values flag instead.")
 	}
 
+	// Resolve the kustomize binary once so PATH lookups are not repeated for every check.
+	bin := r.kustomizeBin()
+	usingKubectl := bin == "kubectl kustomize"
+
 	prevDir, err := os.Getwd()
 	if err != nil {
 		return "", err
@@ -110,46 +114,62 @@ func (r *Runner) KustomizeBuild(srcDir string, tempDir string, opts ...Kustomize
 	}
 
 	if len(kustomizeOpts.Images) > 0 {
+		if usingKubectl {
+			return "", fmt.Errorf("setting images via Chartify values files or kustomize build options is not supported when using 'kubectl kustomize'. Please set images directly in your kustomization.yaml file")
+		}
 		args := []string{"edit", "set", "image"}
 		for _, image := range kustomizeOpts.Images {
 			args = append(args, image.String())
 		}
-		_, err := r.runInDir(tempDir, r.kustomizeBin(), args...)
+		_, err := r.runInDir(tempDir, bin, args...)
 		if err != nil {
 			return "", err
 		}
 	}
 	if kustomizeOpts.NamePrefix != "" {
-		_, err := r.runInDir(tempDir, r.kustomizeBin(), "edit", "set", "nameprefix", kustomizeOpts.NamePrefix)
+		if usingKubectl {
+			return "", fmt.Errorf("setting namePrefix via Chartify values files or kustomize build options is not supported when using 'kubectl kustomize'. Please set namePrefix directly in your kustomization.yaml file")
+		}
+		_, err := r.runInDir(tempDir, bin, "edit", "set", "nameprefix", kustomizeOpts.NamePrefix)
 		if err != nil {
 			fmt.Println(err)
 			return "", err
 		}
 	}
 	if kustomizeOpts.NameSuffix != "" {
+		if usingKubectl {
+			return "", fmt.Errorf("setting nameSuffix via Chartify values files or kustomize build options is not supported when using 'kubectl kustomize'. Please set nameSuffix directly in your kustomization.yaml file")
+		}
 		// "--" is there to avoid `namesuffix -acme` to fail due to `-a` being considered as a flag
-		_, err := r.runInDir(tempDir, r.kustomizeBin(), "edit", "set", "namesuffix", "--", kustomizeOpts.NameSuffix)
+		_, err := r.runInDir(tempDir, bin, "edit", "set", "namesuffix", "--", kustomizeOpts.NameSuffix)
 		if err != nil {
 			return "", err
 		}
 	}
 	if kustomizeOpts.Namespace != "" {
-		_, err := r.runInDir(tempDir, r.kustomizeBin(), "edit", "set", "namespace", kustomizeOpts.Namespace)
+		if usingKubectl {
+			return "", fmt.Errorf("setting namespace via Chartify values files or kustomize build options is not supported when using 'kubectl kustomize'. Please set namespace directly in your kustomization.yaml file")
+		}
+		_, err := r.runInDir(tempDir, bin, "edit", "set", "namespace", kustomizeOpts.Namespace)
 		if err != nil {
 			return "", err
 		}
 	}
 	outputFile := filepath.Join(tempDir, "templates", "kustomized.yaml")
-	kustomizeArgs := []string{"-o", outputFile, "build"}
+	kustomizeArgs := []string{"-o", outputFile}
+
+	if !usingKubectl {
+		kustomizeArgs = append(kustomizeArgs, "build")
+	}
 
 	if u.EnableAlphaPlugins {
-		f, err := r.kustomizeEnableAlphaPluginsFlag()
+		f, err := r.kustomizeEnableAlphaPluginsFlag(usingKubectl)
 		if err != nil {
 			return "", err
 		}
 		kustomizeArgs = append(kustomizeArgs, f)
 	}
-	f, err := r.kustomizeLoadRestrictionsNoneFlag()
+	f, err := r.kustomizeLoadRestrictionsNoneFlag(usingKubectl)
 	if err != nil {
 		return "", err
 	}
@@ -159,7 +179,7 @@ func (r *Runner) KustomizeBuild(srcDir string, tempDir string, opts ...Kustomize
 		kustomizeArgs = append(kustomizeArgs, "--helm-command="+u.HelmBinary)
 	}
 
-	out, err := r.runInDir(tempDir, r.kustomizeBin(), append(kustomizeArgs, tempDir)...)
+	out, err := r.runInDir(tempDir, bin, append(kustomizeArgs, tempDir)...)
 	if err != nil {
 		return "", err
 	}
@@ -193,7 +213,10 @@ func (r *Runner) kustomizeVersion() (*semver.Version, error) {
 // kustomizeEnableAlphaPluginsFlag returns the kustomize binary alpha plugin argument.
 // Above Kustomize v3, it is `--enable-alpha-plugins`.
 // Below Kustomize v3 (including v3), it is `--enable_alpha_plugins`.
-func (r *Runner) kustomizeEnableAlphaPluginsFlag() (string, error) {
+func (r *Runner) kustomizeEnableAlphaPluginsFlag(usingKubectl bool) (string, error) {
+	if usingKubectl {
+		return "--enable-alpha-plugins", nil
+	}
 	version, err := r.kustomizeVersion()
 	if err != nil {
 		return "", err
@@ -208,7 +231,10 @@ func (r *Runner) kustomizeEnableAlphaPluginsFlag() (string, error) {
 // the root argument.
 // Above Kustomize v3, it is `--load-restrictor=LoadRestrictionsNone`.
 // Below Kustomize v3 (including v3), it is `--load_restrictor=none`.
-func (r *Runner) kustomizeLoadRestrictionsNoneFlag() (string, error) {
+func (r *Runner) kustomizeLoadRestrictionsNoneFlag(usingKubectl bool) (string, error) {
+	if usingKubectl {
+		return "--load-restrictor=LoadRestrictionsNone", nil
+	}
 	version, err := r.kustomizeVersion()
 	if err != nil {
 		return "", err

patch.go

@@ -43,6 +43,10 @@ func (r *Runner) Patch(tempDir string, generatedManifestFiles []string, opts ...
 		}
 	}
 
+	// Resolve the kustomize binary once so PATH lookups are not repeated for every check.
+	bin := r.kustomizeBin()
+	usingKubectl := bin == "kubectl kustomize"
+
 	r.Logf("patching files: %v", generatedManifestFiles)
 
 	// Detect if CRDs originally came from templates/ directory
@@ -181,19 +185,26 @@ resources:
 
 	renderedFileName := "all.patched.yaml"
 	renderedFile := filepath.Join(tempDir, renderedFileName)
-	r.Logf("Generating %s", renderedFile)
+	r.Logf("Generating %s", renderedFileName)
+
+	kustomizeArgs := []string{"--output", renderedFile}
 
-	kustomizeArgs := []string{"build", tempDir, "--output", renderedFile}
+	if !usingKubectl {
+		kustomizeArgs = append([]string{"build", tempDir}, kustomizeArgs...)
+	} else {
+		// kubectl kustomize does not use the "build" subcommand; pass tempDir as the target directly.
+		kustomizeArgs = append([]string{tempDir}, kustomizeArgs...)
+	}
 
 	if u.EnableAlphaPlugins {
-		f, err := r.kustomizeEnableAlphaPluginsFlag()
+		f, err := r.kustomizeEnableAlphaPluginsFlag(usingKubectl)
 		if err != nil {
 			return err
 		}
 		kustomizeArgs = append(kustomizeArgs, f)
 	}
 
-	_, err := r.run(nil, r.kustomizeBin(), kustomizeArgs...)
+	_, err := r.run(nil, bin, kustomizeArgs...)
 	if err != nil {
 		return err
 	}

runner.go

@@ -108,6 +108,15 @@ func (r *Runner) kustomizeBin() string {
 	if r.KustomizeBinary != "" {
 		return r.KustomizeBinary
 	}
+	if env := os.Getenv("KUSTOMIZE_BIN"); env != "" {
+		return env
+	}
+	if _, err := exec.LookPath("kustomize"); err == nil {
+		return "kustomize"
+	}
+	if _, err := exec.LookPath("kubectl"); err == nil {
+		return "kubectl kustomize"
+	}
 	return "kustomize"
 }
 
@@ -140,7 +149,7 @@ func (r *Runner) runBytes(envs map[string]string, dir, cmd string, args ...strin
 
 	name := nameArgs[0]
 
-	if len(nameArgs) > 2 {
+	if len(nameArgs) > 1 {
 		a := append([]string{}, nameArgs[1:]...)
 		a = append(a, args...)