fix: Allow for case insensitive header names

samcli/local/apigw/service.py

@@ -14,6 +14,23 @@
 LOG = logging.getLogger(__name__)
 
 
+class CaseInsensitiveDict(dict):
+    """
+    Implement a simple case insensitive dictionary for storing headers. To preserve the original
+    case of the given Header (e.g. X-FooBar-Fizz) this only touches the get and contains magic
+    methods rather than implementing a __setitem__ where we normalize the case of the headers.
+    """
+
+    def __getitem__(self, key):
+        matches = [v for k, v in self.items() if k.lower() == key.lower()]
+        if not matches:
+            raise KeyError(key)
+        return matches[0]
+
+    def __contains__(self, key):
+        return key.lower() in [k.lower() for k in self.keys()]
+
+
 class Route(object):
 
     def __init__(self, methods, function_name, path, binary_types=None):
@@ -270,7 +287,7 @@ def _parse_lambda_output(lambda_output, binary_types, flask_request):
             raise TypeError("Lambda returned %{s} instead of dict", type(json_output))
 
         status_code = json_output.get("statusCode") or 200
-        headers = json_output.get("headers") or {}
+        headers = CaseInsensitiveDict(json_output.get("headers") or {})
         body = json_output.get("body") or "no data"
         is_base_64_encoded = json_output.get("isBase64Encoded") or False
 

tests/functional/function_code.py

@@ -63,6 +63,15 @@
 }
 """
 
+API_GATEWAY_CONTENT_TYPE_LOWER = """
+exports.handler = function(event, context, callback){
+    body = JSON.stringify("hello")
+
+    response = {"statusCode":200,"headers":{"content-type":"text/plain"},"body":body,"isBase64Encoded":false}
+    context.done(null, response);
+}
+"""
+
 API_GATEWAY_ECHO_BASE64_EVENT = """
 exports.base54request = function(event, context, callback){
 

tests/functional/local/apigw/test_service.py

@@ -10,7 +10,7 @@
 from mock import Mock
 
 from samcli.local.apigw.service import Route, Service
-from tests.functional.function_code import nodejs_lambda, API_GATEWAY_ECHO_EVENT, API_GATEWAY_BAD_PROXY_RESPONSE, API_GATEWAY_ECHO_BASE64_EVENT
+from tests.functional.function_code import nodejs_lambda, API_GATEWAY_ECHO_EVENT, API_GATEWAY_BAD_PROXY_RESPONSE, API_GATEWAY_ECHO_BASE64_EVENT, API_GATEWAY_CONTENT_TYPE_LOWER
 from samcli.commands.local.lib import provider
 from samcli.local.lambdafn.runtime import LambdaRuntime
 from samcli.commands.local.lib.local_lambda import LocalLambdaRunner
@@ -63,6 +63,58 @@ def test_non_proxy_response(self):
         self.assertEquals(response.headers.get('Content-Type'), "application/json")
 
 
+class TestService_ContentType(TestCase):
+    @classmethod
+    def setUpClass(cls):
+        cls.code_abs_path = nodejs_lambda(API_GATEWAY_CONTENT_TYPE_LOWER)
+
+        # Let's convert this absolute path to relative path. Let the parent be the CWD, and codeuri be the folder
+        cls.cwd = os.path.dirname(cls.code_abs_path)
+        cls.code_uri = os.path.relpath(cls.code_abs_path, cls.cwd)  # Get relative path with respect to CWD
+
+        cls.function_name = "name"
+
+        cls.function = provider.Function(name=cls.function_name, runtime="nodejs4.3", memory=256, timeout=5,
+                                         handler="index.handler", codeuri=cls.code_uri, environment=None,
+                                         rolearn=None)
+
+        cls.base64_response_function = provider.Function(name=cls.function_name, runtime="nodejs4.3", memory=256, timeout=5,
+                                                         handler="index.handler", codeuri=cls.code_uri, environment=None,
+                                                         rolearn=None)
+
+        cls.mock_function_provider = Mock()
+        cls.mock_function_provider.get.return_value = cls.function
+
+        list_of_routes = [
+                          Route(['GET'], cls.function_name, '/'),
+                          ]
+
+        cls.service, cls.port, cls.url, cls.scheme = make_service(list_of_routes, cls.mock_function_provider, cls.cwd)
+        cls.service.create()
+        t = threading.Thread(name='thread', target=cls.service.run, args=())
+        t.setDaemon(True)
+        t.start()
+
+    @classmethod
+    def tearDownClass(cls):
+        shutil.rmtree(cls.code_abs_path)
+
+    def setUp(self):
+        # Print full diff when comparing large dictionaries
+        self.maxDiff = None
+
+    def test_calling_service_root(self):
+        expected = "hello"
+
+        response = requests.get(self.url)
+
+        actual = response.json()
+
+        self.assertEquals(actual, expected)
+        self.assertEquals(response.status_code, 200)
+        self.assertEquals(response.headers.get('content-type'), "text/plain")
+
+
 class TestService_EventSerialization(TestCase):
     @classmethod
     def setUpClass(cls):

tests/unit/local/apigw/test_service.py

@@ -5,7 +5,7 @@
 
 from parameterized import parameterized, param
 
-from samcli.local.apigw.service import Service, Route
+from samcli.local.apigw.service import Service, Route, CaseInsensitiveDict
 from samcli.local.lambdafn.exceptions import FunctionNotFound
 
 
@@ -525,3 +525,36 @@ def test_should_base64_encode_returns_true(self, test_case_name, binary_types, m
     ])
     def test_should_base64_encode_returns_false(self, test_case_name, binary_types, mimetype):
         self.assertFalse(Service._should_base64_encode(binary_types, mimetype))
+
+
+class TestService_CaseInsensiveDict(TestCase):
+
+    def setUp(self):
+        self.data = CaseInsensitiveDict({
+            'Content-Type': 'text/html',
+            'Browser': 'APIGW',
+        })
+
+    def test_contains_lower(self):
+        self.assertTrue('content-type' in self.data)
+
+    def test_contains_title(self):
+        self.assertTrue('Content-Type' in self.data)
+
+    def test_contains_upper(self):
+        self.assertTrue('CONTENT-TYPE' in self.data)
+
+    def test_contains_browser_key(self):
+        self.assertTrue('Browser' in self.data)
+
+    def test_contains_not_in(self):
+        self.assertTrue('Dog-Food' not in self.data)
+
+    def test_setitem_found(self):
+        self.data['Browser'] = 'APIGW'
+
+        self.assertTrue(self.data['browser'])
+
+    def test_keyerror(self):
+        with self.assertRaises(KeyError):
+            self.data['does-not-exist']