From bd6474c344b4047fd828922a5c5968f162ef20ad Mon Sep 17 00:00:00 2001
From: yxxhero <aiopsclub@163.com>
Date: Sat, 24 Jan 2026 14:00:27 +0800
Subject: [PATCH 1/6] feat: Allow using kubectl built-in kustomize when
 separate kustomize binary is missing

Implements #63: Automatically fallback to kubectl's built-in kustomize when
the standalone kustomize binary is not available.

Changes:
- Modified kustomizeBin() to detect and use kubectl kustomize as fallback
- Fixed runBytes() to properly handle commands with subcommands like 'kubectl kustomize'
- Added isUsingKubectlKustomize() helper to detect when using kubectl kustomize
- Updated kustomizeEnableAlphaPluginsFlag() and kustomizeLoadRestrictionsNoneFlag()
  to skip version detection when using kubectl kustomize
- Added clear error messages for unsupported features (edit subcommands) when using kubectl kustomize
- Modified KustomizeBuild() to omit 'build' argument when using kubectl kustomize
- Modified patch.go to omit 'build' argument and tempDir when using kubectl kustomize
- Added TestKustomizeBin test to verify fallback behavior
- Added TestKubectlKustomizeFallback integration test

Signed-off-by: yxxhero <aiopsclub@163.com>
---
 kubectl_kustomize_test.go | 57 +++++++++++++++++++++++++++++++++++++++
 kustomize.go              | 29 +++++++++++++++++++-
 patch.go                  |  8 ++++--
 runner.go                 | 12 ++++++---
 util_test.go              | 57 +++++++++++++++++++++++++++++++++++++++
 5 files changed, 157 insertions(+), 6 deletions(-)
 create mode 100644 kubectl_kustomize_test.go

diff --git a/kubectl_kustomize_test.go b/kubectl_kustomize_test.go
new file mode 100644
index 0000000..bf0e9a4
--- /dev/null
+++ b/kubectl_kustomize_test.go
@@ -0,0 +1,57 @@
+package chartify
+
+import (
+	"os"
+	"os/exec"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestKubectlKustomizeFallback(t *testing.T) {
+	if _, err := exec.LookPath("kubectl"); err != nil {
+		t.Skip("kubectl binary not found in PATH")
+	}
+
+	t.Run("KustomizeBuild 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")
+		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)
+	})
+}
diff --git a/kustomize.go b/kustomize.go
index f81f3fd..eb1c878 100644
--- a/kustomize.go
+++ b/kustomize.go
@@ -110,6 +110,9 @@ func (r *Runner) KustomizeBuild(srcDir string, tempDir string, opts ...Kustomize
 	}
 
 	if len(kustomizeOpts.Images) > 0 {
+		if r.isUsingKubectlKustomize() {
+			return "", fmt.Errorf("setting images via kustomizeOpts.Images 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())
@@ -120,6 +123,9 @@ func (r *Runner) KustomizeBuild(srcDir string, tempDir string, opts ...Kustomize
 		}
 	}
 	if kustomizeOpts.NamePrefix != "" {
+		if r.isUsingKubectlKustomize() {
+			return "", fmt.Errorf("setting namePrefix via kustomizeOpts.NamePrefix is not supported when using 'kubectl kustomize'. Please set namePrefix directly in your kustomization.yaml file")
+		}
 		_, err := r.runInDir(tempDir, r.kustomizeBin(), "edit", "set", "nameprefix", kustomizeOpts.NamePrefix)
 		if err != nil {
 			fmt.Println(err)
@@ -127,6 +133,9 @@ func (r *Runner) KustomizeBuild(srcDir string, tempDir string, opts ...Kustomize
 		}
 	}
 	if kustomizeOpts.NameSuffix != "" {
+		if r.isUsingKubectlKustomize() {
+			return "", fmt.Errorf("setting nameSuffix via kustomizeOpts.NameSuffix 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)
 		if err != nil {
@@ -134,13 +143,20 @@ func (r *Runner) KustomizeBuild(srcDir string, tempDir string, opts ...Kustomize
 		}
 	}
 	if kustomizeOpts.Namespace != "" {
+		if r.isUsingKubectlKustomize() {
+			return "", fmt.Errorf("setting namespace via kustomizeOpts.Namespace is not supported when using 'kubectl kustomize'. Please set namespace directly in your kustomization.yaml file")
+		}
 		_, err := r.runInDir(tempDir, r.kustomizeBin(), "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 !r.isUsingKubectlKustomize() {
+		kustomizeArgs = append(kustomizeArgs, "build")
+	}
 
 	if u.EnableAlphaPlugins {
 		f, err := r.kustomizeEnableAlphaPluginsFlag()
@@ -190,10 +206,18 @@ func (r *Runner) kustomizeVersion() (*semver.Version, error) {
 	return version, nil
 }
 
+// isUsingKubectlKustomize checks if we're using kubectl's built-in kustomize
+func (r *Runner) isUsingKubectlKustomize() bool {
+	return r.kustomizeBin() == "kubectl kustomize"
+}
+
 // 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) {
+	if r.isUsingKubectlKustomize() {
+		return "--enable-alpha-plugins", nil
+	}
 	version, err := r.kustomizeVersion()
 	if err != nil {
 		return "", err
@@ -209,6 +233,9 @@ func (r *Runner) kustomizeEnableAlphaPluginsFlag() (string, error) {
 // Above Kustomize v3, it is `--load-restrictor=LoadRestrictionsNone`.
 // Below Kustomize v3 (including v3), it is `--load_restrictor=none`.
 func (r *Runner) kustomizeLoadRestrictionsNoneFlag() (string, error) {
+	if r.isUsingKubectlKustomize() {
+		return "--load-restrictor=LoadRestrictionsNone", nil
+	}
 	version, err := r.kustomizeVersion()
 	if err != nil {
 		return "", err
diff --git a/patch.go b/patch.go
index e41c2eb..1229564 100644
--- a/patch.go
+++ b/patch.go
@@ -181,9 +181,13 @@ resources:
 
 	renderedFileName := "all.patched.yaml"
 	renderedFile := filepath.Join(tempDir, renderedFileName)
-	r.Logf("Generating %s", renderedFile)
+	r.Logf("Generating %s", renderedFileName)
 
-	kustomizeArgs := []string{"build", tempDir, "--output", renderedFile}
+	kustomizeArgs := []string{"--output", renderedFile}
+
+	if !r.isUsingKubectlKustomize() {
+		kustomizeArgs = append([]string{"build", tempDir}, kustomizeArgs...)
+	}
 
 	if u.EnableAlphaPlugins {
 		f, err := r.kustomizeEnableAlphaPluginsFlag()
diff --git a/runner.go b/runner.go
index 61eb0ca..4bc5997 100644
--- a/runner.go
+++ b/runner.go
@@ -108,6 +108,12 @@ func (r *Runner) kustomizeBin() string {
 	if r.KustomizeBinary != "" {
 		return r.KustomizeBinary
 	}
+	if _, err := exec.LookPath("kustomize"); err == nil {
+		return "kustomize"
+	}
+	if _, err := exec.LookPath("kubectl"); err == nil {
+		return "kubectl kustomize"
+	}
 	return "kustomize"
 }
 
@@ -140,7 +146,7 @@ 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...)
 
@@ -154,10 +160,10 @@ func (r *Runner) runBytes(envs map[string]string, dir, cmd string, args ...strin
 		wrappedErr := fmt.Errorf(`%w
 
 COMMAND:
-%s
+ %s
 
 OUTPUT:
-%s`,
+ %s`,
 			err,
 			indent(c, "  "),
 			indent(string(errBytes), "  "),
diff --git a/util_test.go b/util_test.go
index 6a944c4..f338897 100644
--- a/util_test.go
+++ b/util_test.go
@@ -1,6 +1,8 @@
 package chartify
 
 import (
+	"os"
+	"os/exec"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
@@ -107,3 +109,58 @@ func TestFindSemVerInfo(t *testing.T) {
 		})
 	}
 }
+
+func TestKustomizeBin(t *testing.T) {
+	t.Run("KustomizeBinary is set", func(t *testing.T) {
+		r := New(KustomizeBin("/custom/kustomize"))
+		got := r.kustomizeBin()
+		want := "/custom/kustomize"
+		if got != want {
+			t.Errorf("kustomizeBin() = %v, want %v", got, want)
+		}
+	})
+
+	t.Run("kustomize binary exists in PATH", func(t *testing.T) {
+		if _, err := exec.LookPath("kustomize"); err != nil {
+			t.Skip("kustomize binary not found in PATH")
+		}
+		r := New()
+		got := r.kustomizeBin()
+		want := "kustomize"
+		if got != want {
+			t.Errorf("kustomizeBin() = %v, want %v", got, want)
+		}
+	})
+
+	t.Run("fallback to kubectl kustomize when kustomize not found", func(t *testing.T) {
+		if _, err := exec.LookPath("kubectl"); err != nil {
+			t.Skip("kubectl binary not found in PATH")
+		}
+		if _, err := exec.LookPath("kustomize"); err == nil {
+			t.Skip("kustomize binary found, cannot test fallback")
+		}
+		r := New()
+		got := r.kustomizeBin()
+		want := "kubectl kustomize"
+		if got != want {
+			t.Errorf("kustomizeBin() = %v, want %v", got, want)
+		}
+	})
+
+	t.Run("KUSTOMIZE_BIN environment variable", func(t *testing.T) {
+		if _, err := exec.LookPath("kustomize"); err != nil {
+			t.Skip("kustomize binary not found in PATH")
+		}
+		if _, ok := os.LookupEnv("KUSTOMIZE_BIN"); ok {
+			t.Skip("KUSTOMIZE_BIN environment variable is already set")
+		}
+		os.Setenv("KUSTOMIZE_BIN", "/custom/kustomize")
+		defer os.Unsetenv("KUSTOMIZE_BIN")
+		r := New(KustomizeBin(os.Getenv("KUSTOMIZE_BIN")))
+		got := r.kustomizeBin()
+		want := "/custom/kustomize"
+		if got != want {
+			t.Errorf("kustomizeBin() = %v, want %v", got, want)
+		}
+	})
+}

From 8fd729b740215dff3417db686e0e0aab21039673 Mon Sep 17 00:00:00 2001
From: yxxhero <aiopsclub@163.com>
Date: Sat, 24 Jan 2026 14:13:57 +0800
Subject: [PATCH 2/6] refactor: Improve tests based on PR review feedback

Address review comments:
- Add KUSTOMIZE_BIN environment variable support to kustomizeBin()
  for consistency with helmBin()
- Make TestKustomizeBin tests deterministic by using fake executables
  and controlled PATH instead of relying on system binaries
- Make TestKubectlKustomizeFallback test self-contained
- Add test for edit commands not supported with kubectl kustomize

Signed-off-by: yxxhero <aiopsclub@163.com>
---
 kubectl_kustomize_test.go | 57 ++++++++++++++++++++++++++--
 runner.go                 |  3 ++
 util_test.go              | 78 ++++++++++++++++++++++++++++-----------
 3 files changed, 112 insertions(+), 26 deletions(-)

diff --git a/kubectl_kustomize_test.go b/kubectl_kustomize_test.go
index bf0e9a4..efc4ad3 100644
--- a/kubectl_kustomize_test.go
+++ b/kubectl_kustomize_test.go
@@ -10,11 +10,11 @@ import (
 )
 
 func TestKubectlKustomizeFallback(t *testing.T) {
-	if _, err := exec.LookPath("kubectl"); err != nil {
-		t.Skip("kubectl binary not found in PATH")
-	}
-
 	t.Run("KustomizeBuild with kubectl kustomize", func(t *testing.T) {
+		if _, err := exec.LookPath("kubectl"); err != nil {
+			t.Skip("kubectl binary not found in PATH")
+		}
+
 		tmpDir := t.TempDir()
 		srcDir := t.TempDir()
 
@@ -54,4 +54,53 @@ spec:
 		require.NoError(t, err)
 		require.FileExists(t, outputFile)
 	})
+
+	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 kustomizeOpts.Images is not supported when using 'kubectl kustomize'")
+	})
 }
diff --git a/runner.go b/runner.go
index 4bc5997..aafdd0f 100644
--- a/runner.go
+++ b/runner.go
@@ -108,6 +108,9 @@ 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"
 	}
diff --git a/util_test.go b/util_test.go
index f338897..e04fccd 100644
--- a/util_test.go
+++ b/util_test.go
@@ -2,10 +2,11 @@ package chartify
 
 import (
 	"os"
-	"os/exec"
+	"path/filepath"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
+	"github.com/stretchr/testify/require"
 )
 
 func TestCreateFlagChain(t *testing.T) {
@@ -111,7 +112,7 @@ func TestFindSemVerInfo(t *testing.T) {
 }
 
 func TestKustomizeBin(t *testing.T) {
-	t.Run("KustomizeBinary is set", func(t *testing.T) {
+	t.Run("KustomizeBinary option is set", func(t *testing.T) {
 		r := New(KustomizeBin("/custom/kustomize"))
 		got := r.kustomizeBin()
 		want := "/custom/kustomize"
@@ -120,25 +121,33 @@ func TestKustomizeBin(t *testing.T) {
 		}
 	})
 
-	t.Run("kustomize binary exists in PATH", func(t *testing.T) {
-		if _, err := exec.LookPath("kustomize"); err != nil {
-			t.Skip("kustomize binary not found in PATH")
+	t.Run("KUSTOMIZE_BIN environment variable", func(t *testing.T) {
+		if _, ok := os.LookupEnv("KUSTOMIZE_BIN"); ok {
+			t.Skip("KUSTOMIZE_BIN environment variable is already set")
 		}
+		os.Setenv("KUSTOMIZE_BIN", "/custom/kustomize")
+		defer os.Unsetenv("KUSTOMIZE_BIN")
 		r := New()
 		got := r.kustomizeBin()
-		want := "kustomize"
+		want := "/custom/kustomize"
 		if got != want {
 			t.Errorf("kustomizeBin() = %v, want %v", got, want)
 		}
 	})
 
 	t.Run("fallback to kubectl kustomize when kustomize not found", func(t *testing.T) {
-		if _, err := exec.LookPath("kubectl"); err != nil {
-			t.Skip("kubectl binary not found in PATH")
-		}
-		if _, err := exec.LookPath("kustomize"); err == nil {
-			t.Skip("kustomize binary found, cannot test fallback")
-		}
+		tmpDir := t.TempDir()
+		binDir := filepath.Join(tmpDir, "bin")
+		require.NoError(t, os.MkdirAll(binDir, 0755))
+
+		kubectlPath := filepath.Join(binDir, "kubectl")
+		kubectlContent := []byte("#!/bin/sh\necho 'kubectl version'\n")
+		require.NoError(t, os.WriteFile(kubectlPath, kubectlContent, 0755))
+
+		origPath := os.Getenv("PATH")
+		defer os.Setenv("PATH", origPath)
+		os.Setenv("PATH", binDir)
+
 		r := New()
 		got := r.kustomizeBin()
 		want := "kubectl kustomize"
@@ -147,18 +156,43 @@ func TestKustomizeBin(t *testing.T) {
 		}
 	})
 
-	t.Run("KUSTOMIZE_BIN environment variable", func(t *testing.T) {
-		if _, err := exec.LookPath("kustomize"); err != nil {
-			t.Skip("kustomize binary not found in PATH")
-		}
-		if _, ok := os.LookupEnv("KUSTOMIZE_BIN"); ok {
-			t.Skip("KUSTOMIZE_BIN environment variable is already set")
+	t.Run("use kustomize when both kustomize and kubectl exist in PATH", func(t *testing.T) {
+		tmpDir := t.TempDir()
+		binDir := filepath.Join(tmpDir, "bin")
+		require.NoError(t, os.MkdirAll(binDir, 0755))
+
+		kustomizePath := filepath.Join(binDir, "kustomize")
+		kustomizeContent := []byte("#!/bin/sh\necho 'kustomize version'\n")
+		require.NoError(t, os.WriteFile(kustomizePath, kustomizeContent, 0755))
+
+		kubectlPath := filepath.Join(binDir, "kubectl")
+		kubectlContent := []byte("#!/bin/sh\necho 'kubectl version'\n")
+		require.NoError(t, os.WriteFile(kubectlPath, kubectlContent, 0755))
+
+		origPath := os.Getenv("PATH")
+		defer os.Setenv("PATH", origPath)
+		os.Setenv("PATH", binDir)
+
+		r := New()
+		got := r.kustomizeBin()
+		want := "kustomize"
+		if got != want {
+			t.Errorf("kustomizeBin() = %v, want %v", got, want)
 		}
-		os.Setenv("KUSTOMIZE_BIN", "/custom/kustomize")
-		defer os.Unsetenv("KUSTOMIZE_BIN")
-		r := New(KustomizeBin(os.Getenv("KUSTOMIZE_BIN")))
+	})
+
+	t.Run("return kustomize as fallback when neither kustomize nor kubectl exist", func(t *testing.T) {
+		tmpDir := t.TempDir()
+		binDir := filepath.Join(tmpDir, "bin")
+		require.NoError(t, os.MkdirAll(binDir, 0755))
+
+		origPath := os.Getenv("PATH")
+		defer os.Setenv("PATH", origPath)
+		os.Setenv("PATH", binDir)
+
+		r := New()
 		got := r.kustomizeBin()
-		want := "/custom/kustomize"
+		want := "kustomize"
 		if got != want {
 			t.Errorf("kustomizeBin() = %v, want %v", got, want)
 		}

From 16b82354943ddbfafe7006a4d798027b4dd49f61 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 2 Apr 2026 08:18:16 +0000
Subject: [PATCH 3/6] refactor: Rename TestKubectlKustomizeFallback to
 TestKubectlKustomize to accurately reflect test purpose

Agent-Logs-Url: https://github.com/helmfile/chartify/sessions/3fa21b29-e929-497e-b448-a711302394ad

Co-authored-by: yxxhero <11087727+yxxhero@users.noreply.github.com>
---
 kubectl_kustomize_test.go | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/kubectl_kustomize_test.go b/kubectl_kustomize_test.go
index efc4ad3..b8103cf 100644
--- a/kubectl_kustomize_test.go
+++ b/kubectl_kustomize_test.go
@@ -9,8 +9,11 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func TestKubectlKustomizeFallback(t *testing.T) {
-	t.Run("KustomizeBuild with kubectl kustomize", func(t *testing.T) {
+// 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) {
 		if _, err := exec.LookPath("kubectl"); err != nil {
 			t.Skip("kubectl binary not found in PATH")
 		}

From 57fe4e34d7d7fd67bfdde7c7867e692d53dea862 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Sun, 12 Apr 2026 00:50:47 +0000
Subject: [PATCH 4/6] fix: Address 4 PR reviewer comments on kustomize fallback
 implementation

Agent-Logs-Url: https://github.com/helmfile/chartify/sessions/6499602a-94b2-481c-ac49-a2fc2d015090

Co-authored-by: yxxhero <11087727+yxxhero@users.noreply.github.com>
---
 kubectl_kustomize_test.go | 30 ++++++++++++++++++++++++++----
 patch.go                  |  3 +++
 runner.go                 |  4 ++--
 util_test.go              | 39 +++++++++++++++++++++++++++++++++++----
 4 files changed, 66 insertions(+), 10 deletions(-)

diff --git a/kubectl_kustomize_test.go b/kubectl_kustomize_test.go
index b8103cf..7590bb8 100644
--- a/kubectl_kustomize_test.go
+++ b/kubectl_kustomize_test.go
@@ -2,7 +2,6 @@ package chartify
 
 import (
 	"os"
-	"os/exec"
 	"path/filepath"
 	"testing"
 
@@ -14,9 +13,32 @@ import (
 // in TestKustomizeBin.
 func TestKubectlKustomize(t *testing.T) {
 	t.Run("KustomizeBuild succeeds with kubectl kustomize option", func(t *testing.T) {
-		if _, err := exec.LookPath("kubectl"); err != nil {
-			t.Skip("kubectl binary not found in PATH")
-		}
+		// Create a stub kubectl that handles the kustomize subcommand,
+		// so this test is self-contained and not skipped when kubectl is absent.
+		stubDir := t.TempDir()
+		stubKubectl := filepath.Join(stubDir, "kubectl")
+		// The stub writes minimal valid YAML to the -o output file.
+		stubScript := []byte(`#!/bin/sh
+# Stub kubectl for testing kubectl kustomize
+if [ "$1" = "kustomize" ]; then
+  shift
+  OUTPUT=""
+  while [ $# -gt 0 ]; do
+    case "$1" in
+      -o) OUTPUT="$2"; shift 2;;
+      *) shift;;
+    esac
+  done
+  if [ -n "$OUTPUT" ]; then
+    printf 'apiVersion: v1\nkind: List\nitems: []\n' > "$OUTPUT"
+  fi
+fi
+`)
+		require.NoError(t, os.WriteFile(stubKubectl, stubScript, 0755))
+
+		origPath := os.Getenv("PATH")
+		defer os.Setenv("PATH", origPath)
+		os.Setenv("PATH", stubDir+":"+origPath)
 
 		tmpDir := t.TempDir()
 		srcDir := t.TempDir()
diff --git a/patch.go b/patch.go
index 1229564..1167039 100644
--- a/patch.go
+++ b/patch.go
@@ -187,6 +187,9 @@ resources:
 
 	if !r.isUsingKubectlKustomize() {
 		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 {
diff --git a/runner.go b/runner.go
index aafdd0f..8bf0827 100644
--- a/runner.go
+++ b/runner.go
@@ -163,10 +163,10 @@ func (r *Runner) runBytes(envs map[string]string, dir, cmd string, args ...strin
 		wrappedErr := fmt.Errorf(`%w
 
 COMMAND:
- %s
+%s
 
 OUTPUT:
- %s`,
+%s`,
 			err,
 			indent(c, "  "),
 			indent(string(errBytes), "  "),
diff --git a/util_test.go b/util_test.go
index e04fccd..92550fa 100644
--- a/util_test.go
+++ b/util_test.go
@@ -122,11 +122,15 @@ func TestKustomizeBin(t *testing.T) {
 	})
 
 	t.Run("KUSTOMIZE_BIN environment variable", func(t *testing.T) {
-		if _, ok := os.LookupEnv("KUSTOMIZE_BIN"); ok {
-			t.Skip("KUSTOMIZE_BIN environment variable is already set")
-		}
+		origVal, hadVal := os.LookupEnv("KUSTOMIZE_BIN")
+		defer func() {
+			if hadVal {
+				os.Setenv("KUSTOMIZE_BIN", origVal)
+			} else {
+				os.Unsetenv("KUSTOMIZE_BIN")
+			}
+		}()
 		os.Setenv("KUSTOMIZE_BIN", "/custom/kustomize")
-		defer os.Unsetenv("KUSTOMIZE_BIN")
 		r := New()
 		got := r.kustomizeBin()
 		want := "/custom/kustomize"
@@ -148,6 +152,15 @@ func TestKustomizeBin(t *testing.T) {
 		defer os.Setenv("PATH", origPath)
 		os.Setenv("PATH", binDir)
 
+		// Ensure KUSTOMIZE_BIN does not override PATH-based lookup.
+		origKustomizeBin, hadKustomizeBin := os.LookupEnv("KUSTOMIZE_BIN")
+		defer func() {
+			if hadKustomizeBin {
+				os.Setenv("KUSTOMIZE_BIN", origKustomizeBin)
+			}
+		}()
+		os.Unsetenv("KUSTOMIZE_BIN")
+
 		r := New()
 		got := r.kustomizeBin()
 		want := "kubectl kustomize"
@@ -173,6 +186,15 @@ func TestKustomizeBin(t *testing.T) {
 		defer os.Setenv("PATH", origPath)
 		os.Setenv("PATH", binDir)
 
+		// Ensure KUSTOMIZE_BIN does not override PATH-based lookup.
+		origKustomizeBin, hadKustomizeBin := os.LookupEnv("KUSTOMIZE_BIN")
+		defer func() {
+			if hadKustomizeBin {
+				os.Setenv("KUSTOMIZE_BIN", origKustomizeBin)
+			}
+		}()
+		os.Unsetenv("KUSTOMIZE_BIN")
+
 		r := New()
 		got := r.kustomizeBin()
 		want := "kustomize"
@@ -190,6 +212,15 @@ func TestKustomizeBin(t *testing.T) {
 		defer os.Setenv("PATH", origPath)
 		os.Setenv("PATH", binDir)
 
+		// Ensure KUSTOMIZE_BIN does not override PATH-based lookup.
+		origKustomizeBin, hadKustomizeBin := os.LookupEnv("KUSTOMIZE_BIN")
+		defer func() {
+			if hadKustomizeBin {
+				os.Setenv("KUSTOMIZE_BIN", origKustomizeBin)
+			}
+		}()
+		os.Unsetenv("KUSTOMIZE_BIN")
+
 		r := New()
 		got := r.kustomizeBin()
 		want := "kustomize"

From 9eaf7ceeae150c424548809f858697d61d40fb08 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Sun, 12 Apr 2026 01:26:50 +0000
Subject: [PATCH 5/6] fix: Address 7 PR reviewer comments on kubectl kustomize
 fallback

Agent-Logs-Url: https://github.com/helmfile/chartify/sessions/3bcd32ca-c9c5-4129-9c6c-87e122e320db

Co-authored-by: yxxhero <11087727+yxxhero@users.noreply.github.com>
---
 kubectl_kustomize_test.go | 68 +++++++++++++++++++++++++++++----------
 kustomize.go              | 44 +++++++++++++------------
 patch.go                  | 10 ++++--
 3 files changed, 82 insertions(+), 40 deletions(-)

diff --git a/kubectl_kustomize_test.go b/kubectl_kustomize_test.go
index 7590bb8..97899b4 100644
--- a/kubectl_kustomize_test.go
+++ b/kubectl_kustomize_test.go
@@ -8,37 +8,46 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-// 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 that handles the kustomize subcommand,
-		// so this test is self-contained and not skipped when kubectl is absent.
-		stubDir := t.TempDir()
-		stubKubectl := filepath.Join(stubDir, "kubectl")
-		// The stub writes minimal valid YAML to the -o output file.
-		stubScript := []byte(`#!/bin/sh
-# Stub kubectl for testing kubectl kustomize
+// 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: v1\nkind: List\nitems: []\n' > "$OUTPUT"
+    printf 'apiVersion: apps/v1\nkind: Deployment\nmetadata:\n  name: stub\n' > "$OUTPUT"
   fi
 fi
-`)
-		require.NoError(t, os.WriteFile(stubKubectl, stubScript, 0755))
+`
+
+// writeStubKubectl creates a stub kubectl script in dir and returns its path.
+func writeStubKubectl(t *testing.T, dir string) string {
+	t.Helper()
+	p := filepath.Join(dir, "kubectl")
+	require.NoError(t, os.WriteFile(p, []byte(stubKubectlScript), 0755))
+	return p
+}
+
+// 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+":"+origPath)
+		os.Setenv("PATH", stubDir+string(os.PathListSeparator)+origPath)
 
 		tmpDir := t.TempDir()
 		srcDir := t.TempDir()
@@ -80,6 +89,31 @@ spec:
 		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()
@@ -126,6 +160,6 @@ spec:
 
 		_, err := r.KustomizeBuild(srcDir, tmpDir, &KustomizeBuildOpts{ValuesFiles: []string{valuesFile}})
 		require.Error(t, err)
-		require.Contains(t, err.Error(), "setting images via kustomizeOpts.Images is not supported when using 'kubectl kustomize'")
+		require.Contains(t, err.Error(), "setting images via Chartify values files or kustomize build options is not supported when using 'kubectl kustomize'")
 	})
 }
diff --git a/kustomize.go b/kustomize.go
index eb1c878..9f729a1 100644
--- a/kustomize.go
+++ b/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
@@ -110,43 +114,43 @@ func (r *Runner) KustomizeBuild(srcDir string, tempDir string, opts ...Kustomize
 	}
 
 	if len(kustomizeOpts.Images) > 0 {
-		if r.isUsingKubectlKustomize() {
-			return "", fmt.Errorf("setting images via kustomizeOpts.Images is not supported when using 'kubectl kustomize'. Please set images directly in your kustomization.yaml file")
+		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 != "" {
-		if r.isUsingKubectlKustomize() {
-			return "", fmt.Errorf("setting namePrefix via kustomizeOpts.NamePrefix is not supported when using 'kubectl kustomize'. Please set namePrefix directly in your kustomization.yaml file")
+		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, r.kustomizeBin(), "edit", "set", "nameprefix", kustomizeOpts.NamePrefix)
+		_, err := r.runInDir(tempDir, bin, "edit", "set", "nameprefix", kustomizeOpts.NamePrefix)
 		if err != nil {
 			fmt.Println(err)
 			return "", err
 		}
 	}
 	if kustomizeOpts.NameSuffix != "" {
-		if r.isUsingKubectlKustomize() {
-			return "", fmt.Errorf("setting nameSuffix via kustomizeOpts.NameSuffix is not supported when using 'kubectl kustomize'. Please set nameSuffix directly in your kustomization.yaml file")
+		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 != "" {
-		if r.isUsingKubectlKustomize() {
-			return "", fmt.Errorf("setting namespace via kustomizeOpts.Namespace is not supported when using 'kubectl kustomize'. Please set namespace directly in your kustomization.yaml file")
+		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, r.kustomizeBin(), "edit", "set", "namespace", kustomizeOpts.Namespace)
+		_, err := r.runInDir(tempDir, bin, "edit", "set", "namespace", kustomizeOpts.Namespace)
 		if err != nil {
 			return "", err
 		}
@@ -154,18 +158,18 @@ func (r *Runner) KustomizeBuild(srcDir string, tempDir string, opts ...Kustomize
 	outputFile := filepath.Join(tempDir, "templates", "kustomized.yaml")
 	kustomizeArgs := []string{"-o", outputFile}
 
-	if !r.isUsingKubectlKustomize() {
+	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
 	}
@@ -175,7 +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
 	}
@@ -214,8 +218,8 @@ func (r *Runner) isUsingKubectlKustomize() bool {
 // 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) {
-	if r.isUsingKubectlKustomize() {
+func (r *Runner) kustomizeEnableAlphaPluginsFlag(usingKubectl bool) (string, error) {
+	if usingKubectl {
 		return "--enable-alpha-plugins", nil
 	}
 	version, err := r.kustomizeVersion()
@@ -232,8 +236,8 @@ 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) {
-	if r.isUsingKubectlKustomize() {
+func (r *Runner) kustomizeLoadRestrictionsNoneFlag(usingKubectl bool) (string, error) {
+	if usingKubectl {
 		return "--load-restrictor=LoadRestrictionsNone", nil
 	}
 	version, err := r.kustomizeVersion()
diff --git a/patch.go b/patch.go
index 1167039..0dbebdf 100644
--- a/patch.go
+++ b/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
@@ -185,7 +189,7 @@ resources:
 
 	kustomizeArgs := []string{"--output", renderedFile}
 
-	if !r.isUsingKubectlKustomize() {
+	if !usingKubectl {
 		kustomizeArgs = append([]string{"build", tempDir}, kustomizeArgs...)
 	} else {
 		// kubectl kustomize does not use the "build" subcommand; pass tempDir as the target directly.
@@ -193,14 +197,14 @@ resources:
 	}
 
 	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
 	}

From 4bc02339f172d2c92f92248866b2f71c7d3bba59 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Sun, 12 Apr 2026 02:06:32 +0000
Subject: [PATCH 6/6] fix: resolve lint errors - drop unused
 isUsingKubectlKustomize and fix writeStubKubectl return

Agent-Logs-Url: https://github.com/helmfile/chartify/sessions/d60019c1-5e03-4997-843e-aeb5ca7d0af6

Co-authored-by: yxxhero <11087727+yxxhero@users.noreply.github.com>
---
 kubectl_kustomize_test.go | 5 ++---
 kustomize.go              | 5 -----
 2 files changed, 2 insertions(+), 8 deletions(-)

diff --git a/kubectl_kustomize_test.go b/kubectl_kustomize_test.go
index 97899b4..fb16b84 100644
--- a/kubectl_kustomize_test.go
+++ b/kubectl_kustomize_test.go
@@ -28,12 +28,11 @@ if [ "$1" = "kustomize" ]; then
 fi
 `
 
-// writeStubKubectl creates a stub kubectl script in dir and returns its path.
-func writeStubKubectl(t *testing.T, dir string) string {
+// 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))
-	return p
 }
 
 // TestKubectlKustomize tests behavior when kubectl kustomize is explicitly configured
diff --git a/kustomize.go b/kustomize.go
index 9f729a1..5a92256 100644
--- a/kustomize.go
+++ b/kustomize.go
@@ -210,11 +210,6 @@ func (r *Runner) kustomizeVersion() (*semver.Version, error) {
 	return version, nil
 }
 
-// isUsingKubectlKustomize checks if we're using kubectl's built-in kustomize
-func (r *Runner) isUsingKubectlKustomize() bool {
-	return r.kustomizeBin() == "kubectl kustomize"
-}
-
 // 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`.