Google PCA Practice Question: Managing and Provisioning a Solution Infrastructure
A developer is writing a Cloud Function that processes files uploaded to a Cloud Storage bucket. Which trigger should they use?
⚠ Common exam trap
PCA often tests the appropriate trigger for a given event source, and candidates might choose Pub/Sub because Cloud Storage can publish to Pub/Sub, but the direct Cloud Storage trigger is the intended answer for simplicity and native integration.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Cloud Storage trigger
To process files uploaded to a Cloud Storage bucket, the developer should use a Cloud Storage trigger. This trigger type is specifically designed to invoke a Cloud Function in response to events in a Cloud Storage bucket, such as object creation, deletion, or metadata updates.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
HTTP trigger
Why it's wrong here
An HTTP trigger only invokes the function when an HTTP request arrives at its endpoint, so uploads to the bucket never reach it. It is tempting because HTTP triggers suit synchronous request-response APIs, such as a webhook or REST endpoint, which is the correct choice when an external client calls the function directly.
- ✗
Firestore trigger
Why it's wrong here
Firestore triggers fire on document create, update, and delete events in Firestore, so they never receive Cloud Storage object events. Cloud Storage uploads require an Eventarc or Cloud Storage trigger. Firestore triggers suit reacting to database writes, such as syncing a document change to another service.
- ✓
Cloud Storage trigger
Why this is correct
A Cloud Storage trigger fires the function in response to object events such as finalise or delete in a bucket, which is exactly the upload-processing pattern described. Eventarc delivers these Cloud Storage events, so no polling or manual invocation is needed.
- ✗
Pub/Sub trigger
Why it's wrong here
A Pub/Sub trigger fires on messages published to a topic, not on object creation events, so bucket uploads would need separate notification wiring. It is tempting because Pub/Sub triggers suit asynchronous event streams and decoupled publishers, which is correct when another service publishes messages to a topic.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Google Cloud exam blueprint
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