The update_function_configuration currently returns an empty dict no matter what but certain lambda libraries (ie, Zappa) require a realistic return value... which is simply the current config after being updated.

https://github.com/localstack/localstack/blob/9cba1010dfcbf2b7672df4d7da46b7e8ab287f64/localstack/services/awslambda/lambda_api.py#L872

https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/lambda.html#Lambda.Client.update_function_configuration

There might also be some other magic enriching that result but my quick read-through looks like it's an empty dict.



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TEST_LAMBDA_CUSTOM_RUNTIME, get_content=True)
        testutil.create_lambda_function(
            func_name=TEST_LAMBDA_NAME_CUSTOM_RUNTIME,
            zip_file=zip_file,
            handler='function.handler',
            runtime=LAMBDA_RUNTIME_CUSTOM_RUNTIME
        )
        result = self.lambda_client.invoke(
            FunctionName=TEST_LAMBDA_NAME_CUSTOM_RUNTIME,
            Payload=b'{"text":"bar with \'quotes\\""}')
        result_data = result['Payload'].read()
        self.assertEqual(result['StatusCode'], 200)
        self.assertEqual(
            to_str(result_data).strip(),
            """Echoing request: '{"text": "bar with \'quotes\\""}'""")
        
        expected = ['.*Custom Runtime Lambda handler executing.']
        self.check_lambda_logs(
            TEST_LAMBDA_NAME_CUSTOM_RUNTIME, expected_lines=expected)
        
        testutil.delete_lambda_function(TEST_LAMBDA_NAME_CUSTOM_RUNTIME)
class TestDotNetCoreRuntimes(LambdaTestBase):
    @classmethod
    def setUpClass(cls):
        cls.lambda_client = aws_stack.connect_to_service('lambda')
        
        zip_file = TEST_LAMBDA_DOTNETCORE2
        cls.zip_file_content = None
        with open(zip_file, 'rb') as file_obj:
            cls.zip_file_content = file_obj.read()