add support for building swagger/OpenAPI JSON

to build, run `make swagger`; a file named `swagger.json` will be
written to the current working directory

awx/api/swagger.py

@@ -0,0 +1,89 @@
+import warnings
+
+from coreapi.document import Object, Link
+
+from rest_framework import exceptions
+from rest_framework.permissions import AllowAny
+from rest_framework.renderers import CoreJSONRenderer
+from rest_framework.response import Response
+from rest_framework.schemas import SchemaGenerator, AutoSchema as DRFAuthSchema
+from rest_framework.views import APIView
+
+from rest_framework_swagger import renderers
+
+
+class AutoSchema(DRFAuthSchema):
+
+    def get_link(self, path, method, base_url):
+        link = super(AutoSchema, self).get_link(path, method, base_url)
+        try:
+            serializer = self.view.get_serializer()
+        except Exception:
+            serializer = None
+            warnings.warn('{}.get_serializer() raised an exception during '
+                          'schema generation. Serializer fields will not be '
+                          'generated for {} {}.'
+                          .format(self.view.__class__.__name__, method, path))
+
+        # auto-generate a topic/tag for the serializer based on its model
+        if hasattr(self.view, 'swagger_topic'):
+            link.__dict__['topic'] = str(self.view.swagger_topic).title()
+        elif serializer and hasattr(serializer, 'Meta'):
+            link.__dict__['topic'] = str(
+                serializer.Meta.model._meta.verbose_name_plural
+            ).title()
+        elif hasattr(self.view, 'model'):
+            link.__dict__['topic'] = str(self.view.model._meta.verbose_name_plural).title()
+        else:
+            warnings.warn('Could not determine a Swagger tag for path {}'.format(path))
+        return link
+
+    def get_description(self, path, method):
+        self.view._request = self.view.request
+        setattr(self.view.request, 'swagger_method', method)
+        description = super(AutoSchema, self).get_description(path, method)
+        return description
+
+
+class SwaggerSchemaView(APIView):
+    _ignore_model_permissions = True
+    exclude_from_schema = True
+    permission_classes = [AllowAny]
+    renderer_classes = [
+        CoreJSONRenderer,
+        renderers.OpenAPIRenderer,
+        renderers.SwaggerUIRenderer
+    ]
+
+    def get(self, request):
+        generator = SchemaGenerator(
+            title='Ansible Tower API',
+            patterns=None,
+            urlconf=None
+        )
+        schema = generator.get_schema(request=request)
+
+        # By default, DRF OpenAPI serialization places all endpoints in
+        # a single node based on their root path (/api).  Instead, we want to
+        # group them by topic/tag so that they're categorized in the rendered
+        # output
+        document = schema._data.pop('api')
+        for path, node in document.items():
+            if isinstance(node, Object):
+                for action in node.values():
+                    topic = getattr(action, 'topic', None)
+                    if topic:
+                        schema._data.setdefault(topic, Object())
+                        schema._data[topic]._data[path] = node
+            elif isinstance(node, Link):
+                topic = getattr(node, 'topic', None)
+                if topic:
+                    schema._data.setdefault(topic, Object())
+                    schema._data[topic]._data[path] = node
+
+        if not schema:
+            raise exceptions.ValidationError(
+                'The schema generator did not return a schema Document'
+            )
+
+        return Response(schema)