fix(idempotency): treat empty or unparsable POWERTOOLS_IDEMPOTENCY_DISABLED as not disabled

aws_lambda_powertools/utilities/idempotency/idempotency.py

@@ -39,6 +39,20 @@
 ContextT = TypeVar("ContextT", bound="LambdaContext | DurableContextProtocol")
 
 
+def _is_idempotency_disabled() -> bool:
+    # An empty or unparsable value is easy to end up with in IaC templates and CI variables;
+    # treat it as "not disabled" instead of failing every invocation
+    value = os.getenv(constants.IDEMPOTENCY_DISABLED_ENV, "false")
+    try:
+        return strtobool(value)
+    except ValueError:
+        logger.debug(
+            f"Ignoring {constants.IDEMPOTENCY_DISABLED_ENV}={value!r}: "
+            "not a recognised boolean, idempotency stays enabled",
+        )
+        return False
+
+
 class _IdempotentHandlerDecorator(Protocol):
     # The return type is Any, as responses replayed from the persistence store are deserialized JSON
     def __call__(
@@ -106,7 +120,7 @@ def handler(event, context):
 
     # Skip idempotency controls when POWERTOOLS_IDEMPOTENCY_DISABLED has a truthy value
     # Raises a warning if not running in development mode
-    if strtobool(os.getenv(constants.IDEMPOTENCY_DISABLED_ENV, "false")):
+    if _is_idempotency_disabled():
         warnings.warn(
             message="Disabling idempotency is intended for development environments only "
             "and should not be used in production.",
@@ -216,7 +230,7 @@ def process_order(customer_id: str, order: dict, **kwargs):
     def decorate(*args, **kwargs):
         # Skip idempotency controls when POWERTOOLS_IDEMPOTENCY_DISABLED has a truthy value
         # Raises a warning if not running in development mode
-        if strtobool(os.getenv(constants.IDEMPOTENCY_DISABLED_ENV, "false")):
+        if _is_idempotency_disabled():
             warnings.warn(
                 message="Disabling idempotency is intended for development environments only "
                 "and should not be used in production.",

tests/functional/idempotency/_boto3/test_idempotency.py

@@ -1704,6 +1704,38 @@ def dummy_handler(event, context):
     assert len(persistence_store.client.method_calls) == 4
 
 
+@pytest.mark.parametrize("idempotency_disabled_value", ["", " ", "maybe", None])
+def test_idempotency_disabled_envvar_empty_or_unparsable(
+    monkeypatch,
+    lambda_context,
+    persistence_store: DynamoDBPersistenceLayer,
+    idempotency_disabled_value,
+):
+    # Scenario to validate an empty, unset or unparsable 'POWERTOOLS_IDEMPOTENCY_DISABLED'
+    # keeps idempotency enabled instead of crashing the invocation
+    mock_event = {"data": "value"}
+
+    persistence_store.client = MagicMock()
+
+    if idempotency_disabled_value is None:
+        monkeypatch.delenv("POWERTOOLS_IDEMPOTENCY_DISABLED", raising=False)
+    else:
+        monkeypatch.setenv("POWERTOOLS_IDEMPOTENCY_DISABLED", idempotency_disabled_value)
+
+    @idempotent_function(data_keyword_argument="data", persistence_store=persistence_store)
+    def dummy(data):
+        return {"message": "hello"}
+
+    @idempotent(persistence_store=persistence_store)
+    def dummy_handler(event, context):
+        return {"message": "hi"}
+
+    assert dummy(data=mock_event) == {"message": "hello"}
+    assert dummy_handler(mock_event, lambda_context) == {"message": "hi"}
+
+    assert len(persistence_store.client.method_calls) == 4
+
+
 @pytest.mark.parametrize("idempotency_config", [{"use_local_cache": True}], indirect=True)
 def test_idempotent_function_duplicates(
     idempotency_config: IdempotencyConfig,