Добавил возможность добавить опционально metrics.html

.gitignore

@@ -176,3 +176,4 @@ cython_debug/
 
 # Django
 staticfiles/
+metrics.html

music_storage/core/templatetags/optional_include.py

@@ -0,0 +1,13 @@
+from django import template
+from django.template.loader import get_template
+from django.template import TemplateDoesNotExist
+
+register = template.Library()
+
+@register.simple_tag(takes_context=True)
+def include_if_exists(context, template_name):
+    try:
+        tpl = get_template(template_name)
+        return tpl.render(context.flatten())
+    except TemplateDoesNotExist:
+        return ""

music_storage/templates/base.html

@@ -24,4 +24,6 @@
     </div>
     {% block content_extra %}{% endblock %}
 </body>
-</html>
+{% load optional_include %}
+{% include_if_exists "metrics.html" %}
+</html>