Event triggered functions in GCP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

What happens when a Cloud Function is triggered by a Pub/Sub event?

You have a Google Cloud Function set to trigger on a Pub/Sub topic message. What is the expected behavior when a new message is published to that topic?

A The Cloud Function runs on a fixed schedule unrelated to message publishing.

B The Cloud Function runs once for each message published to the topic.

C The Cloud Function runs only if the message contains a specific attribute named 'trigger'.

D The Cloud Function runs only once regardless of how many messages are published.

💡 Hint

Think about how event-driven systems respond to each event.

Cloud Functions triggered by Pub/Sub run once for each message published to the topic. Each message is an event that causes the function to execute.

❓ Architecture

intermediate

Choosing the right trigger for a Cloud Function

You want to run a Cloud Function whenever a new file is uploaded to a Cloud Storage bucket. Which trigger should you configure?

A Trigger the function on Cloud Storage 'finalize' event.

B Trigger the function on HTTP request.

C Trigger the function on Pub/Sub topic messages.

D Trigger the function on Cloud Scheduler job.

💡 Hint

Consider which event corresponds to file uploads in Cloud Storage.

The 'finalize' event in Cloud Storage triggers when a new object is created or overwritten, which matches file uploads.

❓ security

advanced

Securing event-triggered Cloud Functions

You have a Cloud Function triggered by Pub/Sub messages. How can you ensure only authorized publishers can trigger the function?

A Set IAM permissions so only authorized identities can publish to the Pub/Sub topic.

B Add a secret token in the message payload and verify it inside the function.

C Make the Cloud Function public and rely on message content validation.

D Use a firewall rule to block all incoming traffic except from known IPs.

💡 Hint

Think about controlling who can send messages to the event source.

By restricting who can publish to the Pub/Sub topic via IAM, you control who can trigger the function. This is the recommended security practice.

❓ Configuration

advanced

Handling retries in event-triggered Cloud Functions

You deploy a Cloud Function triggered by Cloud Storage events. If the function fails, what is the default retry behavior?

A The function retries only if manually triggered again.

B The function is never retried; failed executions are discarded immediately.

C The function retries only once after a fixed delay of 5 minutes.

D The function is retried automatically until it succeeds or the event expires.

💡 Hint

Consider how event delivery guarantees work in Cloud Functions.

Cloud Functions triggered by Cloud Storage events automatically retry on failure until the event expires or the function succeeds.

✅ Best Practice

expert

Optimizing Cloud Function cold start times for event triggers

You notice your event-triggered Cloud Function has high cold start latency. Which approach best reduces cold start delays?

A Increase the function timeout to allow longer execution time.

B Disable concurrency to force single execution at a time.

C Keep the function code small and dependencies minimal to speed startup.

D Use a larger memory allocation to slow down the function.

💡 Hint

Think about what affects how fast a function starts.

Smaller code and fewer dependencies reduce the time needed to load and start the function, lowering cold start latency.