Cloud Digital Leader Practice Question: Google Cloud products, services, and solutions
A developer wants to run a small piece of code that resizes images whenever a new image is uploaded to Cloud Storage. The code runs for less than a second and should only be triggered by the upload event. No always-on server is needed. Which Google Cloud service is ideal?
⚠ Common exam trap
Google Cloud often tests the distinction between event-driven serverless (Cloud Functions) and container-based serverless (Cloud Run), where candidates mistakenly choose Cloud Run because it 'can run code' without realizing it requires an HTTP endpoint and cannot be directly triggered by Cloud Storage events without an intermediary like Eventarc.
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 triggered by Cloud Storage object creation events.
Cloud Functions is the ideal serverless compute service for event-driven, short-lived tasks like image resizing triggered by Cloud Storage uploads. It automatically scales to zero when idle, charges only for execution time (sub-second in this case), and natively binds to Cloud Storage object creation events via the `google.storage.object.finalize` trigger, eliminating the need for any always-on infrastructure.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
A Compute Engine VM that runs continuously, checking for new uploads every minute.
Why it's wrong here
A Compute Engine VM that runs continuously, polling Cloud Storage every minute represents an always-on architecture. It incurs hourly compute costs and requires ongoing maintenance (OS patching, monitoring), even when no uploads occur. Additionally, polling introduces up to 60 seconds of latency and does not scale elastically; the VM may be over-provisioned or under-provisioned for varying upload rates. This contradicts the serverless, event-driven model required.
- ✓
Cloud Functions triggered by Cloud Storage object creation events.
Why this is correct
Cloud Functions triggered by Cloud Storage object creation events are the correct solution because they implement an event-driven, serverless architecture. Each upload to the bucket emits a notification that automatically invokes the function, which resizes the image and returns—no server runs between events. Costs are incurred only for the actual compute time during execution, and the function scales instantly with every individual upload, providing synchronous, low-latency processing.
- ✗
Cloud Run with a permanent container that listens for uploads.
Why it's wrong here
A permanent Cloud Run container contradicts the requirement for no always-on server, implying continuous resource consumption unnecessary for a short-lived, event-driven task. The scenario demands a service that scales to zero and only activates upon the specific upload event. Cloud Run is ideal for containerised web services or APIs that need to be continuously available for incoming requests, scaling down to zero instances when idle, but not for a perpetually running listener as described.
- ✗
BigQuery scheduled query that processes new uploads daily.
Why it's wrong here
A BigQuery scheduled query processes data only at fixed intervals, which cannot react to uploads immediately—introducing up to 24 hours of delay. More fundamentally, BigQuery is a data warehouse for running SQL analytics on tabular data; it is not designed to execute arbitrary code such as image resizing. The service would require cumbersome workarounds (e.g., using UDFs or external scripts) and still lacks the event-driven trigger that the scenario demands. Thus it is both the wrong tool and the wrong execution model.
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
Cloud Digital Transformation
Key term
Cloud Functions
Cloud Functions are serverless compute services that let you run single-purpose code in response to events without managing servers.
Key term
Serverless
Serverless is a cloud computing model where the cloud provider manages the servers, and you only pay for the actual compute time your code uses, without having to worry about provisioning or maintaining infrastructure.
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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.