fix: apply post-renderer to output-dir-template output

When --output-dir and --post-renderer are both passed to helm template,
Helm writes pre-post-renderer content to files and sends post-renderer
output to stdout. This workaround strips --output-dir from helm flags,
captures the post-renderer-processed stdout, and writes it to the output
directory.

Fixes #2515

Signed-off-by: yxxhero <aiopsclub@163.com>

pkg/helmexec/exec.go

@@ -646,17 +646,55 @@ func (helm *execer) TemplateRelease(name string, chart string, flags ...string)
 	helm.logger.Infof("Templating release=%v, chart=%v", name, redactedURL(chart))
 	args := []string{"template", name, chart}
 
-	out, err := helm.exec(append(args, flags...), map[string]string{}, nil)
-
 	var outputToFile bool
+	var hasPostRenderer bool
 
 	for _, f := range flags {
 		if strings.HasPrefix("--output-dir", f) {
 			outputToFile = true
-			break
+		}
+		if f == "--post-renderer" {
+			hasPostRenderer = true
 		}
 	}
 
+	if outputToFile && hasPostRenderer {
+		// Helm 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.
+		// Workaround: run without --output-dir, capture stdout (with post-renderer applied),
+		// and write the output to the output directory ourselves.
+		var outputDir string
+		filteredFlags := make([]string, 0, len(flags))
+		for i := 0; i < len(flags); i++ {
+			if flags[i] == "--output-dir" && i+1 < len(flags) {
+				outputDir = flags[i+1]
+				i++
+				continue
+			}
+			if strings.HasPrefix(flags[i], "--output-dir=") {
+				outputDir = strings.TrimPrefix(flags[i], "--output-dir=")
+				continue
+			}
+			filteredFlags = append(filteredFlags, flags[i])
+		}
+
+		out, err := helm.exec(append(args, filteredFlags...), map[string]string{}, nil)
+		if err != nil {
+			return err
+		}
+
+		if len(out) > 0 {
+			outputPath := filepath.Join(outputDir, name+".yaml")
+			if writeErr := os.WriteFile(outputPath, append(out, '\n'), 0644); writeErr != nil {
+				return writeErr
+			}
+			helm.logger.Debugf("Wrote post-renderer output to %s", outputPath)
+		}
+		return nil
+	}
+
+	out, err := helm.exec(append(args, flags...), map[string]string{}, nil)
+
 	if outputToFile {
 		// With --output-dir is passed to helm-template,
 		// we can safely direct all the logs from it to our logger.

pkg/helmexec/exec_test.go

@@ -1255,6 +1255,46 @@ exec: helm --kubeconfig config --kube-context dev template release https://examp
 	}
 }
 
+func Test_Template_PostRendererWithOutputDir(t *testing.T) {
+	tmpDir := t.TempDir()
+	var buffer bytes.Buffer
+	logger := NewLogger(&buffer, "debug")
+
+	runner := &mockRunner{output: []byte("apiVersion: v1\nkind: Namespace\n")}
+	helm, err := New("helm", HelmExecOptions{}, logger, "config", "dev", runner)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	err = helm.TemplateRelease("myrelease", "path/to/chart",
+		"--post-renderer", "/bin/echo",
+		"--output-dir", tmpDir,
+		"--values", "file.yml",
+	)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	outputPath := filepath.Join(tmpDir, "myrelease.yaml")
+	data, err := os.ReadFile(outputPath)
+	if err != nil {
+		t.Fatalf("expected output file %s to exist: %v", outputPath, err)
+	}
+
+	expected := "apiVersion: v1\nkind: Namespace\n\n"
+	if string(data) != expected {
+		t.Errorf("output file content:\nactual=%q\nexpect=%q", string(data), expected)
+	}
+
+	outputLog := buffer.String()
+	if strings.Contains(outputLog, "--output-dir") {
+		t.Errorf("helm should NOT have been called with --output-dir, got: %s", outputLog)
+	}
+	if !strings.Contains(outputLog, "--post-renderer") {
+		t.Errorf("helm should have been called with --post-renderer, got: %s", outputLog)
+	}
+}
+
 func Test_IsHelm3(t *testing.T) {
 	helm3Runner := mockRunner{output: []byte("v3.0.0+ge29ce2a\n")}
 	helm, err := New("helm", HelmExecOptions{}, NewLogger(os.Stdout, "info"), "", "dev", &helm3Runner)