Use template engine only for .tmpl files

pkg/engine/engine.go

@@ -3,43 +3,54 @@ package engine
 import (
 	"errors"
 	"fmt"
+	"path/filepath"
 	"strings"
 	"text/template"
 )
 
 type Engine struct {
 }
 
+const TEMPLATE_EXT = ".tmpl"
+
 func (e Engine) Render(templates map[string][]byte, values map[string]interface{}) (map[string][]byte, error) {
 	t := template.New("gotpl")
 	t.Funcs(funcMap())
 
 	rendered := make(map[string][]byte)
 
 	for name, data := range templates {
-		_, err := t.New(name).Parse(string(data))
-		if err != nil {
-			// TODO: Inner error message includes prefix "template: ", which does not good when printing this error
-			return nil, fmt.Errorf("failed to parse template: %w", err)
-		}
-
-		var buf strings.Builder
-		if err := t.ExecuteTemplate(&buf, name, values); err != nil {
-			// TODO: Inner error message includes prefix "template: ", which does not good when printing this error
-			return nil, fmt.Errorf("failed to execute template: %w", err)
-		}
-
-		output := buf.String()
-
-		// If template uses variables which were undefined, gotpl will insert "<no value>"
-		if strings.Contains(output, "<no value>") {
-			// TODO: Find out which variable was not defined
-			return nil, errors.New("some of the variables used in the template were undefined")
+		if filepath.Ext(name) == TEMPLATE_EXT {
+			_, err := t.New(name).Parse(string(data))
+			if err != nil {
+				// TODO: Inner error message includes prefix "template: ", which does not good when printing this error
+				return nil, fmt.Errorf("failed to parse template: %w", err)
+			}
+
+			var buf strings.Builder
+			if err := t.ExecuteTemplate(&buf, name, values); err != nil {
+				// TODO: Inner error message includes prefix "template: ", which does not good when printing this error
+				return nil, fmt.Errorf("failed to execute template: %w", err)
+			}
+
+			output := buf.String()
+
+			// If template uses variables which were undefined, gotpl will insert "<no value>"
+			if strings.Contains(output, "<no value>") {
+				// TODO: Find out which variable was not defined
+				return nil, errors.New("some of the variables used in the template were undefined")
+			}
+
+			// TODO: Could we detect unused variables, and give warning about those?
+
+			// Remove template filename extension from destination path
+			destPathRunes := []rune(name)
+			destination := string(destPathRunes[0 : len(destPathRunes)-len(TEMPLATE_EXT)])
+			rendered[destination] = []byte(output)
+		} else {
+			// non-template file, render as is
+			rendered[name] = data
 		}
-
-		// TODO: Could we detect unused variables, and give warning about those?
-
-		rendered[name] = []byte(output)
 	}
 
 	return rendered, nil