WIP: Implemented support for CORS in start-api command

samcli/commands/local/lib/local_api_service.py

@@ -100,7 +100,7 @@ def _make_routing_list(api_provider):
         routes = []
         for api in api_provider.get_all():
             route = Route(methods=[api.method], function_name=api.function_name, path=api.path,
-                          binary_types=api.binary_media_types)
+                          binary_types=api.binary_media_types, cors=api.cors)
             routes.append(route)
 
         return routes

samcli/commands/local/lib/provider.py

@@ -229,7 +229,7 @@ def __hash__(self):
         return hash(self.path) * hash(self.method) * hash(self.function_name)
 
 
-Cors = namedtuple("Cors", ["AllowOrigin", "AllowMethods", "AllowHeaders"])
+Cors = namedtuple("Cors", ["allow_origin", "allow_methods", "allow_headers", "max_age"])
 
 
 class ApiProvider(object):

samcli/commands/local/lib/sam_api_provider.py

@@ -6,7 +6,7 @@
 from six import string_types
 
 from samcli.commands.local.lib.swagger.parser import SwaggerParser
-from samcli.commands.local.lib.provider import ApiProvider, Api
+from samcli.commands.local.lib.provider import ApiProvider, Api, Cors
 from samcli.commands.local.lib.sam_base_provider import SamBaseProvider
 from samcli.commands.local.lib.swagger.reader import SamSwaggerReader
 from samcli.commands.validate.lib.exceptions import InvalidSamDocumentException
@@ -127,6 +127,7 @@ def _extract_from_serverless_api(self, logical_id, api_resource, collector):
         body = properties.get("DefinitionBody")
         uri = properties.get("DefinitionUri")
         binary_media = properties.get("BinaryMediaTypes", [])
+        cors = properties.get("Cors", {})
 
         if not body and not uri:
             # Swagger is not found anywhere.
@@ -146,6 +147,13 @@ def _extract_from_serverless_api(self, logical_id, api_resource, collector):
         collector.add_binary_media_types(logical_id, parser.get_binary_media_types())  # Binary media from swagger
         collector.add_binary_media_types(logical_id, binary_media)  # Binary media specified on resource in template
 
+        collector.add_cors(logical_id, Cors(
+            allow_origin=cors.get("AllowOrigin"),
+            allow_methods=cors.get("AllowMethods"),
+            allow_headers=cors.get("AllowHeaders"),
+            max_age=cors.get("MaxAge")
+        ))
+
     @staticmethod
     def _merge_apis(collector):
         """
@@ -387,6 +395,23 @@ def add_binary_media_types(self, logical_id, binary_media_types):
             else:
                 LOG.debug("Unsupported data type of binary media type value of resource '%s'", logical_id)
 
+    def add_cors(self, logical_id, cors):
+        """
+        Stores the CORS configuration for the API with given logical ID
+
+        Parameters
+        ----------
+        logical_id : str
+            LogicalId of the AWS::Serverless::Api resource
+
+        apis : samcli.commands.local.lib.provider.Cors
+            CORS configuration for the given resource
+        """
+        old_properties = self._get_properties(logical_id)
+        self.by_resource[logical_id] = self.Properties(apis=old_properties.apis,
+                                                       binary_media_types=old_properties.binary_media_types,
+                                                       cors=cors)
+
     def _get_apis_with_config(self, logical_id):
         """
         Returns the list of APIs in this resource along with other extra configuration such as binary media types,

samcli/local/apigw/local_apigw_service.py

@@ -18,18 +18,20 @@
 
 class Route(object):
 
-    def __init__(self, methods, function_name, path, binary_types=None):
+    def __init__(self, methods, function_name, path, binary_types=None, cors=None):
         """
         Creates an ApiGatewayRoute
 
         :param list(str) methods: List of HTTP Methods
         :param function_name: Name of the Lambda function this API is connected to
         :param str path: Path off the base url
+        :param Cors cors: Cors configuration for the route
         """
         self.methods = methods
         self.function_name = function_name
         self.path = path
         self.binary_types = binary_types or []
+        self.cors = cors
 
 
 class LocalApigwService(BaseLocalService):
@@ -43,7 +45,7 @@ def __init__(self, routing_list, lambda_runner, static_dir=None, port=None, host
 
         Parameters
         ----------
-        routing_list list(ApiGatewayCallModel)
+        routing_list list(Route)
             A list of the Model that represent the service paths to create.
         lambda_runner samcli.commands.local.lib.local_lambda.LocalLambdaRunner
             The Lambda runner class capable of invoking the function
@@ -81,10 +83,18 @@ def create(self):
                                                        path):
                 self._dict_of_routes[route_key] = api_gateway_route
 
+            methods = api_gateway_route.methods.copy()
+            if api_gateway_route.cors is not None:
+                methods.append('OPTIONS')
+
+                route_key = self._route_key('OPTIONS', api_gateway_route.path)
+                if route_key not in self._dict_of_routes:
+                    self._dict_of_routes[route_key] = api_gateway_route
+
             self._app.add_url_rule(path,
                                    endpoint=path,
                                    view_func=self._request_handler,
-                                   methods=api_gateway_route.methods,
+                                   methods=methods,
                                    provide_automatic_options=False)
 
         self._construct_error_handling()
@@ -141,6 +151,9 @@ def _request_handler(self, **kwargs):
         """
         route = self._get_current_route(request)
 
+        if request.method == 'OPTIONS':
+            return self.service_response('', LocalApigwService._cors_to_headers(route.cors), 200)
+
         try:
             event = self._construct_event(request, self.port, route.binary_types)
         except UnicodeDecodeError:
@@ -358,3 +371,31 @@ def _should_base64_encode(binary_types, request_mimetype):
 
         """
         return request_mimetype in binary_types or "*/*" in binary_types
+
+
+    @staticmethod
+    def _cors_to_headers(cors):
+        """
+        Convert CORS object to headers dictionary
+
+        Parameters
+        ----------
+        cors list(samcli.commands.local.lib.provider.Cors)
+            CORS configuration objcet
+
+        Returns
+        -------
+            Dictionary with CORS headers
+
+        """
+        headers = {}
+        if cors.allow_origin is not None:
+            headers['Access-Control-Allow-Origin'] = cors.allow_origin[1:-1]
+        if cors.allow_methods is not None:
+            headers['Access-Control-Allow-Methods'] = cors.allow_methods[1:-1]
+        if cors.allow_headers is not None:
+            headers['Access-Control-Allow-Headers'] = cors.allow_headers[1:-1]
+        if cors.max_age is not None:
+            headers['Access-Control-Max-Age'] = cors.max_age[1:-1]
+
+        return headers