handle Django 1.10/1.11 with MIDDLEWARE_CLASSES correctly (#189)

In the case of Django 1.10/1.11, the `MIDDLEWARE` attribute is there,
but may be set to `None` if the old `MIDDLEWARE_CLASSES` setting is still
used.

This change will also ensure that the correct setting name is used in the
error message of the management command.

fixes #188
closes #189

Author: beniwohli

elasticapm/contrib/django/management/commands/elasticapm.py

@@ -204,37 +204,24 @@ def handle_check(self, command, **options):
         self.write('')
 
         # check if middleware is set, and if it is at the first position
-        middleware = list(getattr(settings, 'MIDDLEWARE', getattr(settings, 'MIDDLEWARE_CLASSES', [])))
+        middleware_attr = 'MIDDLEWARE' if getattr(settings, 'MIDDLEWARE', None) is not None else 'MIDDLEWARE_CLASSES'
+        middleware = list(getattr(settings, middleware_attr))
         try:
-            pos = middleware.index(
-                'elasticapm.contrib.django.middleware.TracingMiddleware'
-            )
+            pos = middleware.index('elasticapm.contrib.django.middleware.TracingMiddleware')
             if pos == 0:
-                self.write(
-                    'Tracing middleware is configured! Awesome!',
-                    green
-                )
+                self.write('Tracing middleware is configured! Awesome!', green)
             else:
-                self.write(
-                    'Tracing middleware is configured, but not at the first '
-                    'position\n',
-                    yellow
-                )
-                self.write(
-                    'ElasticAPM works best if you add it at the top of your '
-                    'MIDDLEWARE_CLASSES'
-                )
+                self.write('Tracing middleware is configured, but not at the first position\n', yellow)
+                self.write('ElasticAPM works best if you add it at the top of your %s setting' % middleware_attr)
         except ValueError:
-            self.write(
-                'Tracing middleware not configured!', red
-            )
+            self.write('Tracing middleware not configured!', red)
             self.write(
                 '\n'
-                'Add it to your MIDDLEWARE_CLASSES like this:\n\n'
-                '    MIDDLEWARE_CLASSES = (\n'
+                'Add it to your %(name)s setting like this:\n\n'
+                '    %(name)s = (\n'
                 '        "elasticapm.contrib.django.middleware.TracingMiddleware",\n'
                 '        # your other middleware classes\n'
-                '    )\n'
+                '    )\n' % {'name': middleware_attr}
             )
         self.write('')
         if passed:

tests/contrib/django/django_tests.py

@@ -1143,6 +1143,10 @@ def test_middleware_not_set():
         call_command('elasticapm', 'check', stdout=stdout)
     output = stdout.getvalue()
     assert 'Tracing middleware not configured!' in output
+    if django.VERSION < (1, 10):
+        assert 'MIDDLEWARE_CLASSES' in output
+    else:
+        assert 'MIDDLEWARE setting' in output
 
 
 def test_middleware_not_first():
@@ -1154,6 +1158,26 @@ def test_middleware_not_first():
         call_command('elasticapm', 'check', stdout=stdout)
     output = stdout.getvalue()
     assert 'not at the first position' in output
+    if django.VERSION < (1, 10):
+        assert 'MIDDLEWARE_CLASSES' in output
+    else:
+        assert 'MIDDLEWARE setting' in output
+
+
+@pytest.mark.skipif(not ((1, 10) <= django.VERSION < (2, 0)),
+                    reason='only needed in 1.10 and 1.11 when both middleware settings are valid')
+def test_django_1_10_uses_deprecated_MIDDLEWARE_CLASSES():
+    stdout = compat.StringIO()
+    with override_settings(
+        MIDDLEWARE=None,
+        MIDDLEWARE_CLASSES=[
+            'foo',
+            'elasticapm.contrib.django.middleware.TracingMiddleware'
+        ],
+    ):
+        call_command('elasticapm', 'check', stdout=stdout)
+    output = stdout.getvalue()
+    assert 'not at the first position' in output
 
 
 @mock.patch('elasticapm.transport.http.urllib3.PoolManager.urlopen')