Cloud Functions with Pub/Sub triggers in GCP - Mini Project: Build & Apply

Cloud Functions with Pub/Sub triggers

📖 Scenario: You are building a simple cloud function that reacts to messages published on a Pub/Sub topic. This function will process incoming messages and log their content.

🎯 Goal: Create a Google Cloud Function triggered by a Pub/Sub topic. The function should receive messages, decode them, and log the message data.

📋 What You'll Learn

Create a Pub/Sub topic named my-topic

Create a Cloud Function named process_pubsub_message

Configure the Cloud Function to trigger on messages published to my-topic

The function should decode the base64 message data and log it

💡 Why This Matters

🌍 Real World

Cloud Functions triggered by Pub/Sub are commonly used to process events asynchronously, such as processing user uploads, notifications, or IoT device messages.

💼 Career

Understanding how to connect Pub/Sub with Cloud Functions is essential for cloud developers and engineers working on event-driven architectures in Google Cloud.

1

Create the Pub/Sub topic

Create a Pub/Sub topic named my-topic using the gcloud CLI command.

GCP

# Use the gcloud command to create the topic
# Your code here

Need a hint?

Use the gcloud pubsub topics create command followed by the topic name.

2

Write the Cloud Function code

Write a Python function named process_pubsub_message that accepts event and context parameters. Inside the function, decode the base64 message data from event['data'] and assign it to a variable called message.

GCP

def process_pubsub_message(event, context):
    # Decode the Pub/Sub message data
    # Your code here

Need a hint?

Use the base64 module to decode event['data'] and then decode bytes to a UTF-8 string.

3

Add logging of the message

Inside the process_pubsub_message function, import the logging module and add a line to log the decoded message using logging.info().

GCP

gcloud pubsub topics create my-topic

def process_pubsub_message(event, context):
    import base64
    import logging
    message = base64.b64decode(event['data']).decode('utf-8')
    # Log the message
    # Your code here

Need a hint?

Use logging.info() to log the message with a descriptive text.

4

Deploy the Cloud Function with Pub/Sub trigger

Deploy the Cloud Function named process_pubsub_message using the gcloud CLI. Set the runtime to python39, the trigger to the Pub/Sub topic my-topic, and the entry point to process_pubsub_message.

GCP

gcloud pubsub topics create my-topic

def process_pubsub_message(event, context):
    import base64
    import logging
    message = base64.b64decode(event['data']).decode('utf-8')
    logging.info(f'Received message: {message}')

# Deploy the function using gcloud
# Your code here

Need a hint?

Use gcloud functions deploy with the correct flags for runtime, trigger-topic, and entry-point.