Sending data to PubSub on App Engine standard 2.7

example.py

import base64
import json

# Install google-api-python-client for Py27
import googleapiclient.discovery

def publish(data):
    # The PubSub topic is created beforehand.
    topic = 'projects/my-app-engine-project/topics/my-topic'

    # This will use the service account credentials on App Engine.
    service = googleapiclient.discovery.build('pubsub', 'v1')
    
    data_bytes = base64.b64encode(json.dumps(data))
    body = {
        'messages': [{'data': data_bytes}],
    }
    request = service.projects().topics().publish(topic=topic, body=body)
    response = request.execute()

    return response