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Google ACE Practice Question: A Cloud Function must execute automatically every…
A Cloud Function must execute automatically every time a new object is written to a specific Cloud Storage bucket. Which trigger type should be configured for the function?
⚠ Common exam trap
Google Cloud often tests the misconception that Pub/Sub is required for Cloud Storage events, but Cloud Functions directly supports Cloud Storage triggers without needing an explicit Pub/Sub topic, making Option B a common distractor.
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 (object finalized event)
The Cloud Storage trigger (object finalized event) is the correct choice because Cloud Functions natively supports Cloud Storage events via the `google.storage.object.finalize` event type, which fires when a new object is created or an existing object is overwritten in a bucket. This trigger automatically invokes the function without requiring any intermediary service, directly binding the function to the bucket's notification system.
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 exposes a public HTTPS endpoint and fires the function only when a client sends an HTTP request to that URL. Cloud Storage does not automatically issue HTTP requests to arbitrary function URLs when a new object is created; such a configuration would require custom middleware or a separate webhook mechanism. Without an explicit caller making a request, the function remains dormant, so it cannot respond to storage uploads directly.
- ✗
Pub/Sub trigger
Why it's wrong here
A Pub/Sub trigger subscribes the function to messages published on a designated topic. While Cloud Storage can send object-change notifications to Pub/Sub, that requires separately configuring storage notification filters to publish to the topic. The function would then receive the message only indirectly via Pub/Sub, adding an extra component, whereas the Cloud Storage trigger is a single-step direct binding to the storage event itself.
- ✓
Cloud Storage trigger (object finalized event)
Why this is correct
A Cloud Storage trigger directly registers the function on the `google.cloud.storage.object.v1.finalized` event via Eventarc. When an object is uploaded or overwritten, Cloud Storage emits this event and routes it to the function automatically, with no intermediate service required. The function receives the object's metadata (e.g., bucket, name, size) in its payload, allowing immediate event-driven processing.
- ✗
Cloud Scheduler trigger
Why it's wrong here
Cloud Scheduler is a fully managed cron service that executes jobs on a defined time schedule (e.g., every hour). It does not observe or react to storage events; it can only invoke an HTTP or Pub/Sub target at fixed intervals. Using it for uploads would require polling for new objects, adding latency and running even when no object has changed, making it inefficient and not event-driven.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
Go deeper
Related to this question
Learn chapter
Google Cloud Platform Overview
Key term
Cloud storage
Cloud storage is a service that lets you save data on remote servers accessed over the internet instead of on your computer's hard drive.
Key term
Service
A service is a software component or system that performs a specific function and is available to be used by other programs or users over a network.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This ACE practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the ACE exam.