A rough draft for a more pythonic AWS client

draft.py

import boto3

class Cluster:
    """
    Class to handle an ECS Cluster
    """
    def __init__(self, name, boto3_session):
        assert type(boto3_session) == boto3.session.Session, "Please, provide an boto3 Session as argument!"
        self.name = name
        self.boto3_session = boto3_session
        self.ecs = boto3_session.client('ecs')
        self.__services = []

    @property
    def services(self):
        """
        Lists all the services in a cluster
        """
        if not self.__services:
            data = self.ecs.list_services(cluster=self.name)
            for item in data['serviceArns']:
                self.__services.append(Service(item, self, self.boto3_session))

        return self.__services


class Service:
    """
    Class to handle ECS Services
    """

    __description = None
    __task_definition = None
    __tasks = []

    def __init__(self, name, cluster, boto3_session):
        assert type(boto3_session) == boto3.session.Session, "Please, provide an boto3 Session as argument!"
        self.name = name
        self.cluster = cluster
        self.ecs = boto3_session.client('ecs')

    def update_description(self):
        """
        Calls AWS's describe_services (http://bit.ly/2OHJqm8) to get more data
        about the current service
        """

        data = self.ecs.describe_services(cluster=self.cluster.name, services=[self.name])

        try:
            # Do we have data?
            assert data

            # Is it in the format we expect?
            assert type(data) == dict

            # Do we have failures?
            assert len(data['failures']) == 0

            # Does the metadata points to a successful request?
            assert int(data['ResponseMetadata']['HTTPStatusCode']) < 400

            # Is there actual data in it and do we have exactly one service?
            assert len(data['services']) == 1
           
        except AssertionError as e:
            print("Found an assertion error {}".format(e))
            print("The current state of failures is: ")
            print("\n".join(data['failures']))
        else:
            self.__description = data['services'][0]

    @property
    def task_definition(self):
        if not self.__task_definition:
            if not self.__description:
                self.update_description()
                self.__task_definition = self.__description['taskDefinition']

        return self.__task_definition

def main():
    session = boto3.Session()
    cluster = Cluster("MyCluster", session)
    for service in cluster.services:
        print(service.task_definition)
if __name__ == "__main__":
    main()