def setup_new_topic()

in awscli/customizations/cloudtrail/subscribe.py [0:0]

• 34 lines of code
• 1 McCabe index (conditional complexity)

    def setup_new_topic(self, topic, custom_policy=None):
        """
        Creates a new SNS topic with an appropriate policy to let CloudTrail
        post messages to the topic.
        """
        sys.stdout.write(
            'Setting up new SNS topic {topic}...\n'.format(topic=topic))

        account_id = get_account_id(self.sts)

        # Make sure topic doesn't already exist
        # Warn but do not fail if ListTopics permissions
        # are missing from the IAM role?
        try:
            topics = self.sns.list_topics()['Topics']
        except Exception:
            topics = []
            LOG.warn('Unable to list topics, continuing...')

        if [t for t in topics if t['TopicArn'].split(':')[-1] == topic]:
            raise Exception('Topic {topic} already exists.'.format(
                topic=topic))

        region = self.sns.meta.region_name

        # Get the SNS topic policy information to allow CloudTrail
        # write-access.
        if custom_policy is not None:
            policy = custom_policy
        else:
            policy = self._get_policy(SNS_POLICY_TEMPLATE)

        policy = policy.replace('<Region>', region)\
                       .replace('<SNSTopicOwnerAccountId>', account_id)\
                       .replace('<SNSTopicName>', topic)

        topic_result = self.sns.create_topic(Name=topic)

        try:
            # Merge any existing topic policy with our new policy statements
            topic_attr = self.sns.get_topic_attributes(
                TopicArn=topic_result['TopicArn'])

            policy = self.merge_sns_policy(topic_attr['Attributes']['Policy'],
                                           policy)

            LOG.debug('Topic policy:\n{0}'.format(policy))

            # Set the topic policy
            self.sns.set_topic_attributes(TopicArn=topic_result['TopicArn'],
                                          AttributeName='Policy',
                                          AttributeValue=policy)
        except Exception:
            # Roll back topic creation
            self.sns.delete_topic(TopicArn=topic_result['TopicArn'])
            raise

        return topic_result