chore: last cleanups

Signed-off-by: heitorlessa <[email protected]>

Author: heitorlessa

aws_lambda_powertools/event_handler/api_gateway.py

@@ -206,7 +206,7 @@ def __init__(
         cors: bool,
         compress: bool,
         cache_control: Optional[str],
-        middlewares: Optional[List[Callable[..., Any]]],
+        middlewares: Optional[List[Callable[..., Response]]],
     ):
         """
 
@@ -225,9 +225,8 @@ def __init__(
             Whether or not to enable gzip compression for this route
         cache_control: Optional[str]
             The cache control header value, example "max-age=3600"
-        middlewares: Optional[List[Callable[..., Any]]]
-            The list of route middlewares. These are called in the order they are
-            provided.
+        middlewares: Optional[List[Callable[..., Response]]]
+            The list of route middlewares to be called in order.
         """
         self.method = method.upper()
         self.rule = rule
@@ -238,9 +237,7 @@ def __init__(
         self.cache_control = cache_control
         self.middlewares = middlewares or []
 
-        """
-        _middleware_stack_built is used to ensure the middleware stack is only built once.
-        """
+        # _middleware_stack_built is used to ensure the middleware stack is only built once.
         self._middleware_stack_built = False
 
     def __call__(
@@ -258,7 +255,7 @@ def __call__(
         ----------
         router_middlewares: List[Callable]
             The list of Router Middlewares (assigned to ALL routes)
-        app: Callable
+        app: "ApiGatewayResolver"
             The ApiGatewayResolver instance to pass into the middleware stack
         route_arguments: Dict[str, str]
             The route arguments to pass to the app function (extracted from the Api Gateway
@@ -267,13 +264,11 @@ def __call__(
         Returns
         -------
         Union[Dict, Tuple, Response]
-            Returns an API Response object in ALL cases, excepting when the original API route
-            handler is called which may also return a Dict or Tuple response.
+            API Response object in ALL cases, except when the original API route
+            handler is called which may also return a Dict, Tuple, or Response.
         """
 
-        # Check self._middleware_stack_built to ensure the middleware stack is only built once.
-        # This will save CPU time when an API route is processed multiple times.
-        #
+        # Save CPU cycles by building middleware stack once
         if not self._middleware_stack_built:
             self._build_middleware_stack(router_middlewares=router_middlewares)
 
@@ -312,14 +307,16 @@ def _build_middleware_stack(self, router_middlewares: List[Callable[..., Any]])
         middleware handlers is applied in the order of being added to the handler.
         """
         all_middlewares = router_middlewares + self.middlewares
+        logger.debug(f"Building middleware stack: {all_middlewares}")
 
         # IMPORTANT:
         # this must be the last middleware in the stack (tech debt for backward
-        # compatability purposes)
+        # compatibility purposes)
         #
-        # This adapter will call the registered API passing only the expected route arguments extracted from the path
+        # This adapter will:
+        #   1. Call the registered API passing only the expected route arguments extracted from the path
         # and not the middleware.
-        # This adapter will adapt the response type of the route handler (Union[Dict, Tuple, Response])
+        #   2. Adapt the response type of the route handler (Union[Dict, Tuple, Response])
         # and normalise into a Response object so middleware will always have a constant signature
         all_middlewares.append(_registered_api_adapter)
 
@@ -450,31 +447,42 @@ def route(
 
     def use(self, middlewares: List[Callable[..., Response]]) -> None:
         """
-        Add a list of middlewares to the global router middleware list
+        Add one or more global middlewares that run before/after route specific middleware.
 
-        These middlewares will be called in insertion order and
-        before any middleware registered at the route level.
+        NOTE: Middlewares are called in insertion order.
+
+        Parameters
+        ----------
+        middlewares: List[Callable[..., Response]]
+            List of global middlewares to be used
+
+        Examples
+        --------
 
-        Example
-        -------
         Add middlewares to be used for every request processed by the Router.
 
-        ```
-        my_custom_middleware = new CustomMiddleware()
+        ```python
+        from aws_lambda_powertools import Logger
+        from aws_lambda_powertools.event_handler import APIGatewayRestResolver, Response
+        from aws_lambda_powertools.event_handler.middlewares import NextMiddleware
 
-        app.use([my_custom_middleware])
+        logger = Logger()
+        app = APIGatewayRestResolver()
 
-        ```
+        def log_request_response(app: APIGatewayRestResolver, next_middleware: NextMiddleware) -> Response:
+            logger.info("Incoming request", path=app.current_event.path, request=app.current_event.raw_event)
 
-        Parameters
-        ----------
-        middlewares - List of middlewares to be used
+            result = next_middleware(app)
+            logger.info("Response received", response=result.__dict__)
 
-        Returns
-        -------
-        None
+            return result
 
+        app.use(middlewares=[log_request_response])
 
+
+        def lambda_handler(event, context):
+            return app.resolve(event, context)
+        ```
         """
         self._router_middlewares = self._router_middlewares + middlewares
 
@@ -646,14 +654,14 @@ def lambda_handler(event, context):
     def _push_processed_stack_frame(self, frame: str):
         """
         Add Current Middleware to the Middleware Stack Frames
-        The stack frames will be used when excpetions are thrown and Powertools
+        The stack frames will be used when exceptions are thrown and Powertools
         debug is enabled by developers.
         """
         self.processed_stack_frames.append(frame)
 
     def _reset_processed_stack(self):
         """Reset the Processed Stack Frames"""
-        self.processed_stack_frames = []
+        self.processed_stack_frames.clear()
 
     def append_context(self, **additional_context):
         """Append key=value data as routing context"""
@@ -832,6 +840,7 @@ def __init__(
         self._debug = self._has_debug(debug)
         self._strip_prefixes = strip_prefixes
         self.context: Dict = {}  # early init as customers might add context before event resolution
+        self.processed_stack_frames = []
 
         # Allow for a custom serializer or a concise json serialization
         self._serializer = serializer or partial(json.dumps, separators=(",", ":"), cls=Encoder)
@@ -1005,8 +1014,7 @@ def _resolve(self) -> ResponseBuilder:
             if match_results:
                 logger.debug("Found a registered route. Calling function")
                 # Add matched Route reference into the Resolver context
-                self.append_context(_route=route)
-                self.append_context(_path=path)
+                self.append_context(_route=route, _path=path)
 
                 return self._call_route(route, match_results.groupdict())  # pass fn args
 

aws_lambda_powertools/event_handler/middlewares/base.py

@@ -18,64 +18,64 @@ def __name__(self) -> str:  # noqa A003
 
 
 class BaseMiddlewareHandler(Generic[EventHandlerInstance], ABC):
-    """
-    Base class for Middleware Handlers
+    """Base implementation for Middlewares to run code before and after in a chain.
+
 
     This is the middleware handler function where middleware logic is implemented.
-    Here you have the option to execute code before and after the next handler in the
-    middleware chain is called.  The next middleware handler is represented by `next_middleware`.
+    The next middleware handler is represented by `next_middleware`, returning a Response object.
+
+    Examples
+    --------
 
+    **Correlation ID Middleware**
 
     ```python
+    import requests
 
-    # Place code here for actions BEFORE the next middleware handler is called
-    # or optionally raise an exception to short-circuit the middleware execution chain
+    from aws_lambda_powertools import Logger
+    from aws_lambda_powertools.event_handler import APIGatewayRestResolver, Response
+    from aws_lambda_powertools.event_handler.middlewares import BaseMiddlewareHandler, NextMiddleware
 
-    # Get the response from the NEXT middleware handler (optionally injecting custom
-    # arguments into the next_middleware call)
-    result: Response = next_middleware(app, my_custom_arg="handled")
+    app = APIGatewayRestResolver()
+    logger = Logger()
 
-    # Place code here for actions AFTER the next middleware handler is called
 
-    return result
-    ```
+    class CorrelationIdMiddleware(BaseMiddlewareHandler):
+        def __init__(self, header: str):
+            super().__init__()
+            self.header = header
 
-    To implement ERROR style middleware wrap the call to `next_middleware` in a `try..except`
-    block - you can also catch specific types of errors this way so your middleware only handles
-    specific types of exceptions.
+        def handler(self, app: APIGatewayRestResolver, next_middleware: NextMiddleware) -> Response:
+            # BEFORE logic
+            request_id = app.current_event.request_context.request_id
+            correlation_id = app.current_event.get_header_value(
+                name=self.header,
+                default_value=request_id,
+            )
 
-    for example:
+            # Call next middleware or route handler ('/todos')
+            response = next_middleware(app)
 
-    ```python
+            # AFTER logic
+            response.headers[self.header] = correlation_id
 
-    try:
-        result: Response = next_middleware(app, my_custom_arg="handled")
-    except MyCustomValidationException as e:
-        # Make sure we send back a 400 response for any Custom Validation Exceptions.
-        result.status_code = 400
-        result.body = {"message": "Failed validation"}
-        logger.exception(f"Failed validation when handling route: {app.current_event.path}")
+            return response
 
-    return result
-    ```
 
-    To short-circuit the middleware execution chain you can either raise an exception to cause
-    the function call stack to unwind naturally OR you can simple not call the `next_middleware`
-    handler to get the response from the next middleware handler in the chain.
+    @app.get("/todos", middlewares=[CorrelationIdMiddleware(header="x-correlation-id")])
+    def get_todos():
+        todos: requests.Response = requests.get("https://jsonplaceholder.typicode.com/todos")
+        todos.raise_for_status()
 
-    for example:
-    If you wanted to ensure API callers cannot call a DELETE verb on your API (regardless of defined routes)
-    you could do so with the following middleware implementation.
+        # for brevity, we'll limit to the first 10 only
+        return {"todos": todos.json()[:10]}
 
-    ```python
-    # If invalid http_method is used - return a 405 error
-    # and return early to short-circuit the middleware execution chain
-    if app.current_event.http_method == "DELETE":
-        return Response(status_code=405, body={"message": "DELETE verb not allowed"})
 
+    @logger.inject_lambda_context
+    def lambda_handler(event, context):
+        return app.resolve(event, context)
 
-    # Call the next middleware in the chain (needed for when condition above is valid)
-    return next_middleware(app)
+    ```
 
     """
 
@@ -111,7 +111,7 @@ def __call__(self, app: EventHandlerInstance, next_middleware: NextMiddleware) -
         ----------
         app: ApiGatewayResolver
             An instance of an Event Handler that implements ApiGatewayResolver
-        next_middleware: Callable[..., Any]
+        next_middleware: NextMiddleware
             The next middleware handler in the chain
 
         Returns