def METHOD_NAME(self, params):
    sys.stdout.write(
        'Creating the on-premises instance configuration file named {0}'
        '...'.format(DEFAULT_CONFIG_FILE)
    )
    with open(DEFAULT_CONFIG_FILE, 'w') as f:
        f.write(
            '---\n'
            'region: {0}\n'
            'iam_user_arn: {1}\n'
            'aws_access_key_id: {2}\n'
            'aws_secret_access_key: {3}\n'.format(
                params.region,
                params.iam_user_arn,
                params.access_key_id,
                params.secret_access_key
            )
        )
    sys.stdout.write('DONE\n')