Add api_gateway_response config

chalice/cli/__init__.py

@@ -388,6 +388,7 @@ def generate_models(ctx, stage):
     swagger_generator = TemplatedSwaggerGenerator()
     model = swagger_generator.generate_swagger(
         config.chalice_app,
+        api_gateway_responses=config.api_gateway_responses
     )
     ui = UI()
     ui.write(json.dumps(model, indent=4, cls=PlanEncoder))

chalice/config.py

@@ -248,6 +248,12 @@ def api_gateway_policy_file(self):
         return self._chain_lookup('api_gateway_policy_file',
                                   varies_per_chalice_stage=True)
 
+    @property
+    def api_gateway_responses(self):
+        # type: () -> Dict[str, Dict[str, Dict[str, Any]]]
+        return self._chain_lookup('api_gateway_responses',
+                                  varies_per_chalice_stage=True)
+
     @property
     def minimum_compression_size(self):
         # type: () -> int

chalice/deploy/deployer.py

@@ -887,7 +887,8 @@ def __init__(self, swagger_generator):
     def handle_restapi(self, config, resource):
         # type: (Config, models.RestAPI) -> None
         swagger_doc = self._swagger_generator.generate_swagger(
-            config.chalice_app, resource)
+            config.chalice_app, resource,
+            api_gateway_responses=config.api_gateway_responses)
         resource.swagger_doc = swagger_doc
 
 

chalice/deploy/swagger.py

@@ -33,13 +33,18 @@ def __init__(self, region, deployed_resources):
         self._region = region
         self._deployed_resources = deployed_resources
 
-    def generate_swagger(self, app, rest_api=None):
-        # type: (Chalice, Optional[RestAPI]) -> Dict[str, Any]
+    def generate_swagger(self,
+                         app,                        # type: Chalice
+                         rest_api=None,              # type: Optional[RestAPI]
+                         api_gateway_responses=None  # type: Dict[str, Any]
+                         ):
+        # type: (...) -> Dict[str, Any]
         api = copy.deepcopy(self._BASE_TEMPLATE)
         api['info']['title'] = app.app_name
         self._add_binary_types(api, app)
         self._add_route_paths(api, app)
         self._add_resource_policy(api, rest_api)
+        self._add_api_gateway_responses(api, api_gateway_responses)
         return api
 
     def _add_resource_policy(self, api, rest_api):
@@ -239,6 +244,12 @@ def _add_preflight_request(self, cors, methods, swagger_for_path):
         }
         swagger_for_path['options'] = options_request
 
+    def _add_api_gateway_responses(self, api, api_gateway_responses):
+        # type: (Dict[str, Any], Optional[Dict[str, Any]]) -> None
+        if api_gateway_responses:
+            api.setdefault('x-amazon-apigateway-gateway-responses',
+                           api_gateway_responses)
+
 
 class CFNSwaggerGenerator(SwaggerGenerator):
     def __init__(self):

docs/source/topics/configfile.rst

@@ -58,6 +58,17 @@ a default resource policy on the API if an explicit policy is not specified.
 This value can be a list or a string of endpoint ids.
 
 
+``api_gateway_responses``
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A mapping of key/value pairs. They define how the built-in API Gateway
+responses should be configured. The top level keys should map to a gateway
+response type, e.g. DEFAULT_4XX, and its value should be a mapping defining
+status code, parameters, and/or templates. For more information see examples
+below or check out the `AWS API Gateway docs
+<https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-swagger-extensions-gateway-responses.html>`_
+
+
 ``api_gateway_policy_file``
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -431,6 +442,43 @@ The ``prod`` stage will have these environment variables set::
   }
 
 
+
+API Gateway Responses
+~~~~~~~~~~~~~~~~~~~~~
+
+An example of configuring API Gateway responses would look like this::
+
+    {
+      "version": "2.0",
+      "app_name": "app",
+      "stages": {
+        "dev": {
+          "api_gateway_stage": "dev"
+        }
+      },
+      "api_gateway_responses": {
+        "DEFAULT_4XX": {
+          "responseParameters": {
+            "gatewayresponse.header.Access-Control-Allow-Origin": "'*'"
+          }
+        },
+        "DEFAULT_5XX": {
+          "responseParameters": {
+            "gatewayresponse.header.Access-Control-Allow-Origin": "'*'"
+          }
+        }
+      }
+    }
+
+In this config file, we set up the Default 4XX and Default 5XX API Gateway
+responses to set the Access-Control-Allow-Origin header on responses. This can
+help out with CORS setup so that any error responses are still allowed across
+different origins. For more examples of what you can set, check out the
+`AWS API Gateway docs
+<https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-swagger-extensions-gateway-responses.html>`_
+
+
+
 Per Lambda Examples
 ~~~~~~~~~~~~~~~~~~~
 

tests/unit/deploy/test_deployer.py

@@ -1309,11 +1309,30 @@ def test_can_generate_swagger_builder(self):
             lambda_function=None,
         )
         app = Chalice(app_name='foo')
-        config = Config.create(chalice_app=app)
+        api_gateway_responses = {
+            "DEFAULT_4XX": {
+                "responseParameters": {
+                    "gatewayresponse.header.Access-Control-Allow-Origin":
+                        "'domain.com'"
+                },
+                "responseTemplates": {
+                    "application/json": "{\"message\": test 4xx b }"
+                }
+            },
+            "INVALID_API_KEY": {
+                "statusCode": "429",
+                "responseTemplates": {
+                    "application/json": "{\"message\": test forbidden }"
+                }
+            }
+        }
+        config = Config.create(chalice_app=app,
+                               api_gateway_responses=api_gateway_responses)
         p = SwaggerBuilder(generator)
         p.handle(config, rest_api)
         assert rest_api.swagger_doc == {'swagger': '2.0'}
-        generator.generate_swagger.assert_called_with(app, rest_api)
+        generator.generate_swagger.assert_called_with(
+            app, rest_api, api_gateway_responses=api_gateway_responses)
 
 
 class TestDeploymentPackager(object):

tests/unit/deploy/test_swagger.py

@@ -148,6 +148,33 @@ def test_apigateway_integration_generation(sample_app, swagger_gen):
     assert responses['default'] == {'statusCode': '200'}
 
 
+def test_can_inject_api_gateway_responses(sample_app, swagger_gen):
+    api_gateway_responses = {
+        "DEFAULT_4XX": {
+            "responseParameters": {
+                "gatewayresponse.header.Access-Control-Allow-Origin":
+                    "'domain.com'"
+            },
+            "responseTemplates": {
+                "application/json": "{\"message\": test 4xx b }"
+            }
+        },
+        "INVALID_API_KEY": {
+            "statusCode": "429",
+            "responseTemplates": {
+                "application/json": "{\"message\": test forbidden }"
+            }
+        }
+    }
+    doc = swagger_gen.generate_swagger(
+        sample_app, api_gateway_responses=api_gateway_responses)
+
+    assert 'x-amazon-apigateway-gateway-responses' in doc
+
+    assert doc['x-amazon-apigateway-gateway-responses'] == \
+        api_gateway_responses
+
+
 def test_can_add_url_captures_to_params(sample_app, swagger_gen):
     @sample_app.route('/path/{capture}')
     def foo(name):