Enable binary support by default for ALB events (#528)

Fixes #513.
adamchainz · Oct 7, 2024 · facd679 · facd679
1 parent bbafe4b
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diff --git a/CHANGELOG.rst b/CHANGELOG.rst
@@ -10,6 +10,10 @@ Changelog
 
   Thanks to Zoe Guillen for the report in `PR #496 <https://github.com/adamchainz/apig-wsgi/pull/496>`__.
 
+* Enable binary support by default for ALB events.
+
+  Thanks to Oliver Ford for the report in `Issue #513 <https://github.com/adamchainz/apig-wsgi/issues/513>`__.
+
 * Treat the content-type header "application/problem+json" as non binary by default.
 
   Thanks to Ido Savion in `PR #503 <https://github.com/adamchainz/apig-wsgi/pull/503>`__.

diff --git a/src/apig_wsgi/__init__.py b/src/apig_wsgi/__init__.py
@@ -75,13 +75,23 @@ def handler(event: dict[str, Any], context: Any) -> dict[str, Any]:
             version = event.get("version", "1.0")
 
         if version in ("1.0", "alb"):
-            # Binary support deafults 'off' on version 1
-            event_binary_support = binary_support or False
             environ = get_environ_v1(
                 event,
                 context,
                 encode_query_params=(version == "1.0"),
             )
+            if version == "1.0":
+                # Binary support defaults to 'off' on version 1
+                if binary_support is None:
+                    event_binary_support = False
+                else:
+                    event_binary_support = binary_support
+            else:
+                # Binary support defaults to 'on' on ALBs
+                if binary_support is None:
+                    event_binary_support = True
+                else:
+                    event_binary_support = binary_support
             response: BaseResponse = V1Response(
                 binary_support=event_binary_support,
                 non_binary_content_type_prefixes=non_binary_prefixes_tuple,

diff --git a/tests/test_apig_wsgi.py b/tests/test_apig_wsgi.py
@@ -257,6 +257,34 @@ def test_get_binary_support_binary(self, simple_app: App) -> None:
             "body": b64encode(b"\x13\x37").decode("utf-8"),
         }
 
+    def test_get_binary_support_alb_default(self, simple_app: App) -> None:
+        simple_app.handler = make_lambda_handler(simple_app)
+        simple_app.headers = [("Content-Type", "application/octet-stream")]
+        simple_app.response = b"\x13\x37"
+
+        response = simple_app.handler(make_alb_event(), None)
+
+        assert response == {
+            "statusCode": 200,
+            "multiValueHeaders": {"Content-Type": ["application/octet-stream"]},
+            "isBase64Encoded": True,
+            "body": b64encode(b"\x13\x37").decode("utf-8"),
+        }
+
+    def test_get_binary_support_alb_enabled(self, simple_app: App) -> None:
+        simple_app.handler = make_lambda_handler(simple_app, binary_support=True)
+        simple_app.headers = [("Content-Type", "application/octet-stream")]
+        simple_app.response = b"\x13\x37"
+
+        response = simple_app.handler(make_alb_event(), None)
+
+        assert response == {
+            "statusCode": 200,
+            "multiValueHeaders": {"Content-Type": ["application/octet-stream"]},
+            "isBase64Encoded": True,
+            "body": b64encode(b"\x13\x37").decode("utf-8"),
+        }
+
     @parametrize_default_text_content_type
     def test_get_binary_support_binary_default_text_with_gzip_content_encoding(
         self, simple_app: App, text_content_type: str