fix: make export --format respect "/" in template actions

During tk export path separators are temporarily replaced with BEL in
order to protect paths from being mixed with template output. But when
there is a slash in a template action (e.g. {{index .metadata.labels
"app.kubernetes.io/name"}}, that slash also got replaced, and the
template did not work as expected.

This fix ensures that the BEL replacement only occurs within the text
portions of the template, and the action blocks are being preserved.

Fixes #568

.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+    "go.formatTool": "gofmt"
+}

pkg/tanka/export.go

@@ -175,7 +175,7 @@ func writeExportFile(path string, data []byte) error {
 
 func createTemplate(format string, env manifest.Manifest) (*template.Template, error) {
 	// Replace all os.path separators in string with BelRune for creating subfolders
-	replaceFormat := strings.Replace(format, string(os.PathSeparator), BelRune, -1)
+	replaceFormat := replaceTmplText(format, string(os.PathSeparator), BelRune)
 
 	envMap := template.FuncMap{"env": func() manifest.Manifest { return env }}
 
@@ -189,6 +189,24 @@ func createTemplate(format string, env manifest.Manifest) (*template.Template, e
 	return template, nil
 }
 
+func replaceTmplText(s, old, new string) string {
+	parts := []string{}
+	l := strings.Index(s, "{{")
+	r := strings.Index(s, "}}") + 2
+
+	for l != -1 && l < r {
+		// replace only in text between template action blocks
+		text := strings.ReplaceAll(s[:l], old, new)
+		action := s[l:r]
+		parts = append(parts, text, action)
+		s = s[r:]
+		l = strings.Index(s, "{{")
+		r = strings.Index(s, "}}") + 2
+	}
+	parts = append(parts, strings.ReplaceAll(s, old, new))
+	return strings.Join(parts, "")
+}
+
 func applyTemplate(template *template.Template, m manifest.Manifest) (path string, err error) {
 	buf := bytes.Buffer{}
 	if err := template.Execute(&buf, m); err != nil {

pkg/tanka/export_test.go

@@ -0,0 +1,33 @@
+package tanka
+
+import "testing"
+
+func Test_replaceTmplText(t *testing.T) {
+	type args struct {
+		s   string
+		old string
+		new string
+	}
+	tests := []struct {
+		name string
+		args args
+		want string
+	}{
+		{"text only", args{"a", "a", "b"}, "b"},
+		{"action blocks", args{"{{a}}{{.}}", "a", "b"}, "{{a}}{{.}}"},
+		{"mixed", args{"a{{a}}a{{a}}a", "a", "b"}, "b{{a}}b{{a}}b"},
+		{"invalid template format handled as text", args{"a}}a{{a", "a", "b"}, "b}}b{{b"},
+		{
+			name: "keep path separator in action block",
+			args: args{`{{index .metadata.labels "app.kubernetes.io/name"}}/{{.metadata.name}}`, "/", BelRune},
+			want: "{{index .metadata.labels \"app.kubernetes.io/name\"}}\u0007{{.metadata.name}}",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := replaceTmplText(tt.args.s, tt.args.old, tt.args.new); got != tt.want {
+				t.Errorf("replaceInTmplText() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}