Etapa 1: criar um novo ledger

Nesta etapa, você cria um novo ledger do Amazon QLDB chamado vehicle-registration.

Para criar um novo ledger

1. Examine o arquivo a seguir (constants.py), que contém valores constantes usados por todos os outros programas deste tutorial.

   # 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.
   
   
   class Constants:
       """
       Constant values used throughout this tutorial.
       """
       LEDGER_NAME = "vehicle-registration"
   
       VEHICLE_REGISTRATION_TABLE_NAME = "VehicleRegistration"
       VEHICLE_TABLE_NAME = "Vehicle"
       PERSON_TABLE_NAME = "Person"
       DRIVERS_LICENSE_TABLE_NAME = "DriversLicense"
   
       LICENSE_NUMBER_INDEX_NAME = "LicenseNumber"
       GOV_ID_INDEX_NAME = "GovId"
       VEHICLE_VIN_INDEX_NAME = "VIN"
       LICENSE_PLATE_NUMBER_INDEX_NAME = "LicensePlateNumber"
       PERSON_ID_INDEX_NAME = "PersonId"
   
       JOURNAL_EXPORT_S3_BUCKET_NAME_PREFIX = "qldb-tutorial-journal-export"
       USER_TABLES = "information_schema.user_tables"
       S3_BUCKET_ARN_TEMPLATE = "arn:aws:s3:::"
       LEDGER_NAME_WITH_TAGS = "tags"
   
       RETRY_LIMIT = 4

2. Use o programa a seguir (create_ledger.py) para criar um ledger chamado vehicle-registration.

   # 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
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   qldb_client = client('qldb')
   
   LEDGER_CREATION_POLL_PERIOD_SEC = 10
   ACTIVE_STATE = "ACTIVE"
   
   
   def create_ledger(name):
       """
       Create a new ledger with the specified name.
   
       :type name: str
       :param name: Name for the ledger to be created.
   
       :rtype: dict
       :return: Result from the request.
       """
       logger.info("Let's create the ledger named: {}...".format(name))
       result = qldb_client.create_ledger(Name=name, PermissionsMode='ALLOW_ALL')
       logger.info('Success. Ledger state: {}.'.format(result.get('State')))
       return result
   
   
   def wait_for_active(name):
       """
       Wait for the newly created ledger to become active.
   
       :type name: str
       :param name: The ledger to check on.
   
       :rtype: dict
       :return: Result from the request.
       """
       logger.info('Waiting for ledger to become active...')
       while True:
           result = qldb_client.describe_ledger(Name=name)
           if result.get('State') == ACTIVE_STATE:
               logger.info('Success. Ledger is active and ready to use.')
               return result
           logger.info('The ledger is still creating. Please wait...')
           sleep(LEDGER_CREATION_POLL_PERIOD_SEC)
   
   
   def main(ledger_name=Constants.LEDGER_NAME):
       """
       Create a ledger and wait for it to be active.
       """
       try:
           create_ledger(ledger_name)
           wait_for_active(ledger_name)
       except Exception as e:
           logger.exception('Unable to create the ledger!')
           raise e
   
   
   if __name__ == '__main__':
       main()

   nota

   • Na chamada create_ledger, você deve especificar um nome de ledger e um modo de permissões. Recomendamos o uso do modo de permissões STANDARD para maximizar a segurança dos dados do seu ledger.

   • Ao criar um ledger, a proteção contra exclusão é habilitada, por padrão. Esse é um atributo que impede que um ledger seja excluído por qualquer usuário. Você tem a opção de desativar a proteção contra exclusão na criação do ledger usando a API QLDB ou o AWS Command Line Interface (AWS CLI).

   • Se preferir, especifique também tags para anexar ao ledger.

3. Para executar o programa, digite o comando a seguir.

   python create_ledger.py

Para verificar sua conexão com o novo ledger, vá para Etapa 2: Testar a conectividade com o ledger.