feat(apigateway): ignore trailing slashes in routes (APIGatewayRestResolver)

aws_lambda_powertools/event_handler/api_gateway.py

@@ -46,6 +46,7 @@
 # API GW/ALB decode non-safe URI chars; we must support them too
 _UNSAFE_URI = "%<> \[\]{}|^"  # noqa: W605
 _NAMED_GROUP_BOUNDARY_PATTERN = rf"(?P\1[{_SAFE_URI}{_UNSAFE_URI}\\w]+)"
+_ROUTE_REGEX = "^{}$"
 
 
 class ProxyEventType(Enum):
@@ -562,7 +563,7 @@ def _has_debug(debug: Optional[bool] = None) -> bool:
         return powertools_dev_is_set()
 
     @staticmethod
-    def _compile_regex(rule: str):
+    def _compile_regex(rule: str, base_regex: str = _ROUTE_REGEX):
         """Precompile regex pattern
 
         Logic
@@ -592,7 +593,7 @@ def _compile_regex(rule: str):
         NOTE: See #520 for context
         """
         rule_regex: str = re.sub(_DYNAMIC_ROUTE_PATTERN, _NAMED_GROUP_BOUNDARY_PATTERN, rule)
-        return re.compile("^{}$".format(rule_regex))
+        return re.compile(base_regex.format(rule_regex))
 
     def _to_proxy_event(self, event: Dict) -> BaseProxyEvent:
         """Convert the event dict to the corresponding data class"""
@@ -819,6 +820,24 @@ def __init__(
         """Amazon API Gateway REST and HTTP API v1 payload resolver"""
         super().__init__(ProxyEventType.APIGatewayProxyEvent, cors, debug, serializer, strip_prefixes)
 
+    # override route to ignore trailing "/" in routes for REST API
+    def route(
+        self,
+        rule: str,
+        method: Union[str, Union[List[str], Tuple[str]]],
+        cors: Optional[bool] = None,
+        compress: bool = False,
+        cache_control: Optional[str] = None,
+    ):
+        # remove trailing "/" character from route rule for correct routing behaviour
+        return super().route(rule.rstrip("/"), method, cors, compress, cache_control)
+
+    # Override _compile_regex to exclude trailing slashes for route resolution
+    @staticmethod
+    def _compile_regex(rule: str, base_regex: str = _ROUTE_REGEX):
+
+        return super(APIGatewayRestResolver, APIGatewayRestResolver)._compile_regex(rule, "^{}/*$")
+
 
 class APIGatewayHttpResolver(ApiGatewayResolver):
     current_event: APIGatewayProxyEventV2

tests/e2e/event_handler/handlers/alb_handler.py

@@ -4,7 +4,7 @@
 
 
 @app.post("/todos")
-def hello():
+def todos():
     payload = app.current_event.json_body
 
     body = payload.get("body", "Hello World")
@@ -22,5 +22,10 @@ def hello():
     )
 
 
+@app.get("/hello")
+def hello():
+    return Response(status_code=200, content_type=content_types.TEXT_PLAIN, body="Hello World")
+
+
 def lambda_handler(event, context):
     return app.resolve(event, context)

tests/e2e/event_handler/handlers/api_gateway_http_handler.py

@@ -8,7 +8,7 @@
 
 
 @app.post("/todos")
-def hello():
+def todos():
     payload = app.current_event.json_body
 
     body = payload.get("body", "Hello World")
@@ -26,5 +26,10 @@ def hello():
     )
 
 
+@app.get("/hello")
+def hello():
+    return Response(status_code=200, content_type=content_types.TEXT_PLAIN, body="Hello World")
+
+
 def lambda_handler(event, context):
     return app.resolve(event, context)

tests/e2e/event_handler/handlers/api_gateway_rest_handler.py

@@ -8,7 +8,7 @@
 
 
 @app.post("/todos")
-def hello():
+def todos():
     payload = app.current_event.json_body
 
     body = payload.get("body", "Hello World")
@@ -26,5 +26,10 @@ def hello():
     )
 
 
+@app.get("/hello")
+def hello():
+    return Response(status_code=200, content_type=content_types.TEXT_PLAIN, body="Hello World")
+
+
 def lambda_handler(event, context):
     return app.resolve(event, context)

tests/e2e/event_handler/handlers/lambda_function_url_handler.py

@@ -8,7 +8,7 @@
 
 
 @app.post("/todos")
-def hello():
+def todos():
     payload = app.current_event.json_body
 
     body = payload.get("body", "Hello World")
@@ -26,5 +26,10 @@ def hello():
     )
 
 
+@app.get("/hello")
+def hello():
+    return Response(status_code=200, content_type=content_types.TEXT_PLAIN, body="Hello World")
+
+
 def lambda_handler(event, context):
     return app.resolve(event, context)

tests/e2e/event_handler/infrastructure.py

@@ -64,6 +64,11 @@ def _create_api_gateway_http(self, function: Function):
             integration=apigwv2integrations.HttpLambdaIntegration("TodosIntegration", function),
         )
 
+        apigw.add_routes(
+            path="/hello",
+            methods=[apigwv2.HttpMethod.GET],
+            integration=apigwv2integrations.HttpLambdaIntegration("HelloIntegration", function),
+        )
         CfnOutput(self.stack, "APIGatewayHTTPUrl", value=(apigw.url or ""))
 
     def _create_api_gateway_rest(self, function: Function):
@@ -72,6 +77,9 @@ def _create_api_gateway_rest(self, function: Function):
         todos = apigw.root.add_resource("todos")
         todos.add_method("POST", apigwv1.LambdaIntegration(function, proxy=True))
 
+        hello = apigw.root.add_resource("hello")
+        hello.add_method("GET", apigwv1.LambdaIntegration(function, proxy=True))
+
         CfnOutput(self.stack, "APIGatewayRestUrl", value=apigw.url)
 
     def _create_lambda_function_url(self, function: Function):

tests/e2e/event_handler/test_paths_ending_with_slash.py

@@ -0,0 +1,95 @@
+import pytest
+from requests import HTTPError, Request
+
+from tests.e2e.utils import data_fetcher
+
+
+@pytest.fixture
+def alb_basic_listener_endpoint(infrastructure: dict) -> str:
+    dns_name = infrastructure.get("ALBDnsName")
+    port = infrastructure.get("ALBBasicListenerPort", "")
+    return f"http://{dns_name}:{port}"
+
+
+@pytest.fixture
+def alb_multi_value_header_listener_endpoint(infrastructure: dict) -> str:
+    dns_name = infrastructure.get("ALBDnsName")
+    port = infrastructure.get("ALBMultiValueHeaderListenerPort", "")
+    return f"http://{dns_name}:{port}"
+
+
+@pytest.fixture
+def apigw_rest_endpoint(infrastructure: dict) -> str:
+    return infrastructure.get("APIGatewayRestUrl", "")
+
+
+@pytest.fixture
+def apigw_http_endpoint(infrastructure: dict) -> str:
+    return infrastructure.get("APIGatewayHTTPUrl", "")
+
+
+@pytest.fixture
+def lambda_function_url_endpoint(infrastructure: dict) -> str:
+    return infrastructure.get("LambdaFunctionUrl", "")
+
+
+def test_api_gateway_rest_trailing_slash(apigw_rest_endpoint):
+    # GIVEN
+    url = f"{apigw_rest_endpoint}hello/"
+    body = "Hello World"
+    status_code = 200
+
+    # WHEN
+    response = data_fetcher.get_http_response(
+        Request(
+            method="GET",
+            url=url,
+        )
+    )
+
+    # THEN
+    assert response.status_code == status_code
+    # response.content is a binary string, needs to be decoded to compare with the real string
+    assert response.content.decode("ascii") == body
+
+
+def test_api_gateway_http_trailing_slash(apigw_http_endpoint):
+    # GIVEN the URL for the API ends in a trailing slash API gateway should return a 404
+    url = f"{apigw_http_endpoint}hello/"
+
+    # WHEN
+    with pytest.raises(HTTPError):
+        data_fetcher.get_http_response(
+            Request(
+                method="GET",
+                url=url,
+            )
+        )
+
+
+def test_lambda_function_url_trailing_slash(lambda_function_url_endpoint):
+    # GIVEN the URL for the API ends in a trailing slash it should behave as if there was not one
+    url = f"{lambda_function_url_endpoint}hello/"  # the function url endpoint already has the trailing /
+
+    # WHEN
+    with pytest.raises(HTTPError):
+        data_fetcher.get_http_response(
+            Request(
+                method="GET",
+                url=url,
+            )
+        )
+
+
+def test_alb_url_trailing_slash(alb_multi_value_header_listener_endpoint):
+    # GIVEN url has a trailing slash - it should behave as if there was not one
+    url = f"{alb_multi_value_header_listener_endpoint}/hello/"
+
+    # WHEN
+    with pytest.raises(HTTPError):
+        data_fetcher.get_http_response(
+            Request(
+                method="GET",
+                url=url,
+            )
+        )

tests/events/albEventPathTrailingSlash.json

@@ -0,0 +1,28 @@
+{
+    "requestContext": {
+      "elb": {
+        "targetGroupArn": "arn:aws:elasticloadbalancing:us-east-2:123456789012:targetgroup/lambda-279XGJDqGZ5rsrHC2Fjr/49e9d65c45c6791a"
+      }
+    },
+    "httpMethod": "GET",
+    "path": "/lambda/",
+    "queryStringParameters": {
+      "query": "1234ABCD"
+    },
+    "headers": {
+      "accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8",
+      "accept-encoding": "gzip",
+      "accept-language": "en-US,en;q=0.9",
+      "connection": "keep-alive",
+      "host": "lambda-alb-123578498.us-east-2.elb.amazonaws.com",
+      "upgrade-insecure-requests": "1",
+      "user-agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36",
+      "x-amzn-trace-id": "Root=1-5c536348-3d683b8b04734faae651f476",
+      "x-forwarded-for": "72.12.164.125",
+      "x-forwarded-port": "80",
+      "x-forwarded-proto": "http",
+      "x-imforwards": "20"
+    },
+    "body": "Test",
+    "isBase64Encoded": false
+  }

tests/events/apiGatewayProxyEventPathTrailingSlash.json

@@ -0,0 +1,80 @@
+{
+    "version": "1.0",
+    "resource": "/my/path",
+    "path": "/my/path/",
+    "httpMethod": "GET",
+    "headers": {
+      "Header1": "value1",
+      "Header2": "value2"
+    },
+    "multiValueHeaders": {
+      "Header1": [
+        "value1"
+      ],
+      "Header2": [
+        "value1",
+        "value2"
+      ]
+    },
+    "queryStringParameters": {
+      "parameter1": "value1",
+      "parameter2": "value"
+    },
+    "multiValueQueryStringParameters": {
+      "parameter1": [
+        "value1",
+        "value2"
+      ],
+      "parameter2": [
+        "value"
+      ]
+    },
+    "requestContext": {
+      "accountId": "123456789012",
+      "apiId": "id",
+      "authorizer": {
+        "claims": null,
+        "scopes": null
+      },
+      "domainName": "id.execute-api.us-east-1.amazonaws.com",
+      "domainPrefix": "id",
+      "extendedRequestId": "request-id",
+      "httpMethod": "GET",
+      "identity": {
+        "accessKey": null,
+        "accountId": null,
+        "caller": null,
+        "cognitoAuthenticationProvider": null,
+        "cognitoAuthenticationType": null,
+        "cognitoIdentityId": null,
+        "cognitoIdentityPoolId": null,
+        "principalOrgId": null,
+        "sourceIp": "192.168.0.1/32",
+        "user": null,
+        "userAgent": "user-agent",
+        "userArn": null,
+        "clientCert": {
+          "clientCertPem": "CERT_CONTENT",
+          "subjectDN": "www.example.com",
+          "issuerDN": "Example issuer",
+          "serialNumber": "a1:a1:a1:a1:a1:a1:a1:a1:a1:a1:a1:a1:a1:a1:a1:a1",
+          "validity": {
+            "notBefore": "May 28 12:30:02 2019 GMT",
+            "notAfter": "Aug  5 09:36:04 2021 GMT"
+          }
+        }
+      },
+      "path": "/my/path",
+      "protocol": "HTTP/1.1",
+      "requestId": "id=",
+      "requestTime": "04/Mar/2020:19:15:17 +0000",
+      "requestTimeEpoch": 1583349317135,
+      "resourceId": null,
+      "resourcePath": "/my/path",
+      "stage": "$default"
+    },
+    "pathParameters": null,
+    "stageVariables": null,
+    "body": "Hello from Lambda!",
+    "isBase64Encoded": true
+  }