From b20b6b5f143e2e0fa12d88a0c406951f3af8f255 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Sun, 26 Apr 2026 01:06:27 +0000
Subject: [PATCH] fix: restrict --output-dir + --post-renderer workaround to
 Helm 3 only

Agent-Logs-Url: https://github.com/helmfile/helmfile/sessions/229b14e2-b1ad-4f19-bd00-b8f7821383cd

Co-authored-by: yxxhero <11087727+yxxhero@users.noreply.github.com>
---
 pkg/helmexec/exec.go                      |  5 +++--
 pkg/helmexec/exec_test.go                 | 18 +++++++++++++-----
 test/integration/test-cases/issue-2515.sh |  2 +-
 3 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/pkg/helmexec/exec.go b/pkg/helmexec/exec.go
index ec1454fb..acc73fc6 100644
--- a/pkg/helmexec/exec.go
+++ b/pkg/helmexec/exec.go
@@ -658,9 +658,10 @@ func (helm *execer) TemplateRelease(name string, chart string, flags ...string)
 		}
 	}
 
-	if outputToFile && hasPostRenderer {
-		// Helm does not apply --post-renderer to files written by --output-dir.
+	if outputToFile && hasPostRenderer && helm.IsHelm3() {
+		// Helm 3 does not apply --post-renderer to files written by --output-dir.
 		// It writes pre-post-renderer content to files and sends post-renderer output to stdout.
+		// Helm 4 handles this correctly, so the workaround is only needed for Helm 3.
 		// Workaround: run without --output-dir, capture stdout (with post-renderer applied),
 		// and write the output to the output directory ourselves.
 		var outputDir string
diff --git a/pkg/helmexec/exec_test.go b/pkg/helmexec/exec_test.go
index 760315a8..109c6b30 100644
--- a/pkg/helmexec/exec_test.go
+++ b/pkg/helmexec/exec_test.go
@@ -21,8 +21,9 @@ import (
 // Mocking the command-line runner
 
 type mockRunner struct {
-	output []byte
-	err    error
+	output        []byte
+	versionOutput []byte // if set, returned for "helm version --short" probe; overrides default Helm 4 fallback
+	err           error
 }
 
 func (mock *mockRunner) ExecuteStdIn(cmd string, args []string, env map[string]string, stdin io.Reader) ([]byte, error) {
@@ -30,8 +31,13 @@ func (mock *mockRunner) ExecuteStdIn(cmd string, args []string, env map[string]s
 }
 
 func (mock *mockRunner) Execute(cmd string, args []string, env map[string]string, enableLiveOutput bool) ([]byte, error) {
-	if len(mock.output) == 0 && strings.Join(args, " ") == "version --short" {
-		return []byte("v4.0.1+g12500dd"), nil
+	if strings.Join(args, " ") == "version --short" {
+		if mock.versionOutput != nil {
+			return mock.versionOutput, nil
+		}
+		if len(mock.output) == 0 {
+			return []byte("v4.0.1+g12500dd"), nil
+		}
 	}
 	return mock.output, mock.err
 }
@@ -1260,7 +1266,9 @@ func Test_Template_PostRendererWithOutputDir(t *testing.T) {
 	var buffer bytes.Buffer
 	logger := NewLogger(&buffer, "debug")
 
-	runner := &mockRunner{}
+	// Use Helm 3 version for the version probe so the Helm 3 workaround is applied.
+	// The workaround is not needed for Helm 4, which natively applies --post-renderer to --output-dir output.
+	runner := &mockRunner{versionOutput: []byte("v3.20.0")}
 	helm, err := New("helm", HelmExecOptions{}, logger, "config", "dev", runner)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
diff --git a/test/integration/test-cases/issue-2515.sh b/test/integration/test-cases/issue-2515.sh
index c99023f8..b18b2ee3 100644
--- a/test/integration/test-cases/issue-2515.sh
+++ b/test/integration/test-cases/issue-2515.sh
@@ -2,7 +2,7 @@ issue_2515_case_dir="$(cd "${cases_dir}/issue-2515" && pwd)"
 issue_2515_tmp=$(mktemp -d)
 
 if [ "${HELMFILE_HELM4}" = "1" ]; then
-    info "Skipping issue-2515 test for Helm 4 (post-renderer requires plugin)"
+    info "Skipping issue-2515 test for Helm 4 (Helm 4 natively applies --post-renderer to --output-dir output)"
     test_start "issue-2515 post-renderer with output-dir-template (skipped for Helm 4)"
     test_pass "issue-2515 post-renderer with output-dir-template (skipped for Helm 4)"
 else