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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result = set_function_code(data, function)
    arn = func_arn(function)
    func_details = arn_to_lambda.get(arn)
    result.update(format_func_details(func_details))
    if isinstance(result, Response):
        return result
    return jsonify(result or {})
@app.route('%s/functions/<function>/code' % PATH_ROOT, methods=['GET'])
def get_function_code(function):
    """ Get the code of an existing function
        ---
        operationId: 'getFunctionCode'
        parameters:
    """
    arn = func_arn(function)
    lambda_cwd = arn_to_lambda[arn].cwd
    tmp_file = '%s/%s' % (lambda_cwd, LAMBDA_ZIP_FILE_NAME)
    return Response(load_file(tmp_file, mode='rb'),
            mimetype='application/zip',
            headers={'Content-Disposition': 'attachment; filename=lambda_archive.zip'})
@app.route('%s/functions/<function>/configuration' % PATH_ROOT, methods=['GET'])
def get_function_configuration(function):
    """ Get the configuration of an existing function
        ---
        operationId: 'getFunctionConfiguration'
        parameters:
    """
    arn = func_arn(function)
    lambda_details = arn_to_lambda.get(arn)
    if not lambda_details: