fix(event_handler): CORS Origin for ALBResolver multi-headers (#4385)

Author: leandrodamascena

aws_lambda_powertools/event_handler/api_gateway.py

@@ -43,7 +43,7 @@
     validation_error_definition,
     validation_error_response_definition,
 )
-from aws_lambda_powertools.event_handler.util import _FrozenDict
+from aws_lambda_powertools.event_handler.util import _FrozenDict, extract_origin_header
 from aws_lambda_powertools.shared.cookies import Cookie
 from aws_lambda_powertools.shared.functions import powertools_dev_is_set
 from aws_lambda_powertools.shared.json_encoder import Encoder
@@ -782,7 +782,8 @@ def __init__(
 
     def _add_cors(self, event: ResponseEventT, cors: CORSConfig):
         """Update headers to include the configured Access-Control headers"""
-        self.response.headers.update(cors.to_dict(event.get_header_value("Origin")))
+        extracted_origin_header = extract_origin_header(event.resolved_headers_field)
+        self.response.headers.update(cors.to_dict(extracted_origin_header))
 
     def _add_cache_control(self, cache_control: str):
         """Set the specified cache control headers for 200 http responses. For non-200 `no-cache` is used."""
@@ -2129,7 +2130,8 @@ def _not_found(self, method: str) -> ResponseBuilder:
         headers = {}
         if self._cors:
             logger.debug("CORS is enabled, updating headers.")
-            headers.update(self._cors.to_dict(self.current_event.get_header_value("Origin")))
+            extracted_origin_header = extract_origin_header(self.current_event.resolved_headers_field)
+            headers.update(self._cors.to_dict(extracted_origin_header))
 
             if method == "OPTIONS":
                 logger.debug("Pre-flight request detected. Returning CORS with null response")

aws_lambda_powertools/event_handler/util.py

@@ -1,3 +1,8 @@
+from typing import Any, Dict
+
+from aws_lambda_powertools.utilities.data_classes.shared_functions import get_header_value
+
+
 class _FrozenDict(dict):
     """
     A dictionary that can be used as a key in another dictionary.
@@ -11,3 +16,27 @@ class _FrozenDict(dict):
 
     def __hash__(self):
         return hash(frozenset(self.keys()))
+
+
+def extract_origin_header(resolver_headers: Dict[str, Any]):
+    """
+    Extracts the 'origin' or 'Origin' header from the provided resolver headers.
+
+    The 'origin' or 'Origin' header can be either a single header or a multi-header.
+
+    Args:
+        resolver_headers (Dict): A dictionary containing the headers.
+
+    Returns:
+        Optional[str]: The value(s) of the origin header or None.
+    """
+    resolved_header = get_header_value(
+        headers=resolver_headers,
+        name="origin",
+        default_value=None,
+        case_sensitive=False,
+    )
+    if isinstance(resolved_header, list):
+        return resolved_header[0]
+
+    return resolved_header

docs/index.md

@@ -89,7 +89,7 @@ You can install Powertools for AWS Lambda (Python) using your favorite dependenc
             === "CDK"
 
                 ```python hl_lines="13 19"
-                --8<-- "examples/homepage/install/x86_64/cdk.py"
+                --8<-- "examples/homepage/install/x86_64/cdk_x86.py"
                 ```
 
             === "Terraform"
@@ -101,7 +101,7 @@ You can install Powertools for AWS Lambda (Python) using your favorite dependenc
             === "Pulumi"
 
                 ```python hl_lines="21-27"
-                --8<-- "examples/homepage/install/x86_64/pulumi.py"
+                --8<-- "examples/homepage/install/x86_64/pulumi_x86.py"
                 ```
 
             === "Amplify"
@@ -127,7 +127,7 @@ You can install Powertools for AWS Lambda (Python) using your favorite dependenc
             === "CDK"
 
                 ```python hl_lines="13 19"
-                --8<-- "examples/homepage/install/arm64/cdk.py"
+                --8<-- "examples/homepage/install/arm64/cdk_arm64.py"
                 ```
 
             === "Terraform"
@@ -139,7 +139,7 @@ You can install Powertools for AWS Lambda (Python) using your favorite dependenc
             === "Pulumi"
 
                 ```python hl_lines="21-27"
-                --8<-- "examples/homepage/install/arm64/pulumi.py"
+                --8<-- "examples/homepage/install/arm64/pulumi_arm64.py"
                 ```
 
             === "Amplify"
@@ -275,7 +275,7 @@ Compared with the [public Layer ARN](#lambda-layer) option, SAR allows you to ch
     === "CDK"
 
         ```python hl_lines="7 16-20 23-27"
-        --8<-- "examples/homepage/install/sar/cdk.py"
+        --8<-- "examples/homepage/install/sar/cdk_sar.py"
         ```
 
     === "Terraform"

examples/homepage/install/arm64/cdk.py renamed to examples/homepage/install/arm64/cdk_arm64.py

@@ -12,6 +12,12 @@ disable_error_code = annotation-unchecked
 [mypy-jmespath]
 ignore_missing_imports=True
 
+[mypy-pulumi.*]
+ignore_missing_imports=True
+
+[mypy-pulumi_aws.*]
+ignore_missing_imports=True
+
 [mypy-aws_encryption_sdk.*]
 ignore_missing_imports=True
 

examples/homepage/install/arm64/pulumi.py renamed to examples/homepage/install/arm64/pulumi_arm64.py

@@ -12,6 +12,9 @@
     "Header1": [
       "value1"
     ],
+    "Origin": [
+      "https://aws.amazon.com"
+    ],
     "Header2": [
       "value1",
       "value2"