subscriber.py

import argparse

def list_subscriptions_in_topic(project_id, topic_name):
    from google.cloud import pubsub_v1
    publisher = pubsub_v1.PublisherClient()
    topic_path = publisher.topic_path(project_id, topic_name)
    for subscription in publisher.list_topic_subscriptions(topic_path):
        print(subscription)


def create_subscription(project_id, topic_name, subscription_name):
    from google.cloud import pubsub_v1
    subscriber = pubsub_v1.SubscriberClient()
    topic_path = subscriber.topic_path(project_id, topic_name)
    subscription_path = subscriber.subscription_path(
        project_id, subscription_name)
    subscription = subscriber.create_subscription(
        subscription_path, topic_path)
    print('Subscription created: {}'.format(subscription))

def receive_messages(project_id, subscription_name):
    import time
    from google.cloud import pubsub_v1
    subscriber = pubsub_v1.SubscriberClient()
    subscription_path = subscriber.subscription_path(
        project_id, subscription_name)

    def callback(message):
        print('Received message: {}'.format(message))
        message.ack()
        
    subscriber.subscribe(subscription_path, callback=callback)
    print('Listening for messages on {}'.format(subscription_path))
    while True:
        time.sleep(60)

if __name__ == '__main__':
    parser = argparse.ArgumentParser(
        description=__doc__,
        formatter_class=argparse.RawDescriptionHelpFormatter
    )
    parser.add_argument('project_id', help='Your Google Cloud project ID')

    subparsers = parser.add_subparsers(dest='command')
    list_in_topic_parser = subparsers.add_parser(
        'list_in_topic', help=list_subscriptions_in_topic.__doc__)
    list_in_topic_parser.add_argument('topic_name')

    create_parser = subparsers.add_parser(
        'create', help=create_subscription.__doc__)
    create_parser.add_argument('topic_name')
    create_parser.add_argument('subscription_name')

    receive_parser = subparsers.add_parser(
        'receive', help=receive_messages.__doc__)
    receive_parser.add_argument('subscription_name')

    args = parser.parse_args()

    if args.command == 'list_in_topic':
        list_subscriptions_in_topic(args.project_id, args.topic_name)
    elif args.command == 'create':
        create_subscription(
            args.project_id, args.topic_name, args.subscription_name)
    elif args.command == 'receive':
        receive_messages(args.project_id, args.subscription_name)