Cloud Digital Leader Google Cloud Products and Services Practice Question
A developer wants to trigger a serverless function whenever a new object is uploaded to a Cloud Storage bucket. Which Google Cloud service should they use?
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 Functions
Cloud Functions is an event-driven serverless compute service that can be triggered by Cloud Storage events such as object finalise/create. Cloud Run can also be triggered by events via Eventarc, but Cloud Functions is the simpler choice for small code snippets triggered by events. Dataflow and App Engine are not designed for event-triggered functions from Cloud Storage.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Cloud Functions
Why this is correct
Cloud Functions is the correct choice because it is Google Cloud's event-driven serverless compute service designed to respond directly to Cloud Storage events. Specifically, Cloud Functions natively subscribes to the `google.storage.object.finalize` event, which is emitted whenever an object is uploaded or overwritten in a bucket. This background function type requires no custom intermediary, as the event is delivered automatically and the function can immediately process the object, making it the most direct and efficient mechanism for triggering on object uploads.
- ✗
Cloud Run
Why it's wrong here
Cloud Run deploys containerised applications that respond to HTTP requests, but it lacks native event-arc triggers for Cloud Storage object finalisation events; the correct service, Cloud Functions, directly subscribes to bucket notifications via Pub/Sub. It is tempting because Cloud Run can handle HTTP-triggered workloads and might be chosen for containerised code, but it would require a custom intermediary like Eventarc to receive storage events, adding unnecessary complexity.
- ✗
App Engine
Why it's wrong here
App Engine is a Platform-as-a-Service (PaaS) solution built for hosting web applications and services that respond to HTTP requests. While App Engine can scale automatically and be written in various languages, it does not have a native Cloud Storage event trigger; it cannot subscribe directly to `google.storage.object.finalize` events. To act on object uploads, an App Engine app would need to receive an HTTP notification routed through a separate service like Pub/Sub or a third-party webhook, adding extra moving parts and latency. This indirect approach is neither natural nor recommended compared to Cloud Functions' built-in event integration.
- ✗
Dataflow
Why it's wrong here
Dataflow is a managed service for executing Apache Beam pipelines, primarily intended for batch and stream data processing at scale. It does not serve as an event trigger mechanism for Cloud Storage; rather, it is the downstream processing engine that would consume data after some trigger initiates a job. To react to an object finalization event, you would still need something like Cloud Functions or Pub/Sub to invoke the Dataflow job, since Dataflow itself has no native subscription to `google.storage.object.finalize`. This makes Dataflow an unnecessary and incorrect layer for the simple act of triggering on an upload, as it is designed to process data, not to originate event-driven responses.
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
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Cloud Digital Transformation
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
Cloud Functions
Cloud Functions are serverless compute services that let you run single-purpose code in response to events without managing servers.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This GCDL 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 GCDL exam.