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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if isinstance(e, ClientError):
            return e.get_response()
        return error_response('Unknown error: %s %s' % (e, traceback.format_exc()))
@app.route('%s/functions/<function>' % PATH_ROOT, methods=['GET'])
def get_function(function):
    """ Get details for a single function
        ---
        operationId: 'getFunction'
        parameters:
            - name: 'request'
              in: body
            - name: 'function'
              in: path
    """
    funcs = do_list_functions()
    for func in funcs:
        if func['FunctionName'] == function:
            result = {
                'Configuration': func,
                'Code': {
                    'Location': '%s/code' % request.url
                }
            }
            lambda_details = arn_to_lambda.get(func['FunctionArn'])
            if lambda_details.concurrency is not None:
                result['Concurrency'] = lambda_details.concurrency
            return jsonify(result)
    return not_found_error(func_arn(function))
@app.route('%s/functions/' % PATH_ROOT, methods=['GET'])
def list_functions():