Step 8 (optional): Clean up resources - Amazon Quantum Ledger Database (Amazon QLDB)

Step 8 (optional): Clean up resources

You can continue using the vehicle-registration ledger. However, if you no longer need it, you should delete it.

To delete the ledger

  1. Use the following program (delete_ledger.py) to delete your vehicle-registration ledger and all of its contents.

    # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX-License-Identifier: MIT-0
#
# Permission is hereby granted, free of charge, to any person obtaining a copy of this
# software and associated documentation files (the "Software"), to deal in the Software
# without restriction, including without limitation the rights to use, copy, modify,
# merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
# INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
# PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#
# This code expects that you have AWS credentials setup per:
# https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
from logging import basicConfig, getLogger, INFO
from time import sleep

from boto3 import client

from pyqldbsamples.constants import Constants
from pyqldbsamples.describe_ledger import describe_ledger

logger = getLogger(__name__)
basicConfig(level=INFO)
qldb_client = client('qldb')

LEDGER_DELETION_POLL_PERIOD_SEC = 20


def delete_ledger(ledger_name):
    """
    Send a request to QLDB to delete the specified ledger.

    :type ledger_name: str
    :param ledger_name: Name for the ledger to be deleted.

    :rtype: dict
    :return: Result from the request.
    """
    logger.info('Attempting to delete the ledger with name: {}...'.format(ledger_name))
    result = qldb_client.delete_ledger(Name=ledger_name)
    logger.info('Success.')
    return result


def wait_for_deleted(ledger_name):
    """
    Wait for the ledger to be deleted.

    :type ledger_name: str
    :param ledger_name: The ledger to check on.
    """
    logger.info('Waiting for the ledger to be deleted...')
    while True:
        try:
            describe_ledger(ledger_name)
            logger.info('The ledger is still being deleted. Please wait...')
            sleep(LEDGER_DELETION_POLL_PERIOD_SEC)
        except qldb_client.exceptions.ResourceNotFoundException:
            logger.info('Success. The ledger is deleted.')
            break


def set_deletion_protection(ledger_name, deletion_protection):
    """
    Update an existing ledger's deletion protection.

    :type ledger_name: str
    :param ledger_name: Name of the ledger to update.

    :type deletion_protection: bool
    :param deletion_protection: Enable or disable the deletion protection.

    :rtype: dict
    :return: Result from the request.
    """
    logger.info("Let's set deletion protection to {} for the ledger with name {}.".format(deletion_protection,
                                                                                          ledger_name))
    result = qldb_client.update_ledger(Name=ledger_name, DeletionProtection=deletion_protection)
    logger.info('Success. Ledger updated: {}'.format(result))


def main(ledger_name=Constants.LEDGER_NAME):
    """
    Delete a ledger.
    """
    try:
        set_deletion_protection(ledger_name, False)
        delete_ledger(ledger_name)
        wait_for_deleted(ledger_name)
    except Exception as e:
        logger.exception('Unable to delete the ledger.')
        raise e


if __name__ == '__main__':
    main()
    Note

    If deletion protection is enabled for your ledger, you must first disable it before you can delete the ledger using the QLDB API.

    The delete_ledger.py file also has a dependency on the following program (describe_ledger.py).

    # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX-License-Identifier: MIT-0
#
# Permission is hereby granted, free of charge, to any person obtaining a copy of this
# software and associated documentation files (the "Software"), to deal in the Software
# without restriction, including without limitation the rights to use, copy, modify,
# merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
# INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
# PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#
# This code expects that you have AWS credentials setup per:
# https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
from logging import basicConfig, getLogger, INFO

from boto3 import client

from pyqldbsamples.constants import Constants

logger = getLogger(__name__)
basicConfig(level=INFO)
qldb_client = client('qldb')


def describe_ledger(ledger_name):
    """
    Describe a ledger.

    :type ledger_name: str
    :param ledger_name: Name of the ledger to describe.
    """
    logger.info('describe ledger with name: {}.'.format(ledger_name))
    result = qldb_client.describe_ledger(Name=ledger_name)
    result.pop('ResponseMetadata')
    logger.info('Success. Ledger description: {}.'.format(result))
    return result


def main(ledger_name=Constants.LEDGER_NAME):
    """
    Describe a QLDB ledger.
    """
    try:
        describe_ledger(ledger_name)
    except Exception as e:
        logger.exception('Unable to describe a ledger.')
        raise e


if __name__ == '__main__':
    main()

  2. To run the program, enter the following command.

    python delete_ledger.py