Google ACE Setting Up a Cloud Solution Environment Practice Question
A developer needs to authenticate to Google Cloud from their local machine to run application code that reads from Cloud Storage. They use a service account. Which gcloud command should they use to obtain application credentials?
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
✓
gcloud auth activate-service-account --key-file=KEY_FILE
The command 'gcloud auth application-default login' obtains user credentials for Application Default Credentials (ADC). For a service account, they would use 'gcloud auth activate-service-account' or set the GOOGLE_APPLICATION_CREDENTIALS environment variable.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
gcloud auth login
Why it's wrong here
The `gcloud auth login` command triggers an interactive OAuth flow that authenticates you as a Google user account, not as a service account. It stores user credentials in the gcloud config directory and is intended for human users accessing Cloud Console or gcloud with their own identity. It cannot use a service account's JSON key file, so it is fundamentally the wrong tool for authenticating as a service account.
- ✗
gcloud config set account service-account@project.iam.gserviceaccount.com
Why it's wrong here
The `gcloud config set account` command merely changes the active account property in your gcloud configuration to point to an already-authenticated identity. It does not perform any authentication handshake or validate credentials; it only tells gcloud which existing credential set to use in subsequent commands. If the service account has not been previously authenticated via `activate-service-account`, this command will not establish any credentials and will lead to authentication failures.
- ✗
gcloud auth application-default login
Why it's wrong here
The `gcloud auth application-default login` command creates User Application Default Credentials (ADC) that are used by Google Cloud client libraries to discover credentials, not by gcloud itself. It authenticates with a human user's account, typically via a browser OAuth flow, and stores credentials for ADC, not for a service account. To authenticate as a service account for ADC, you would set the `GOOGLE_APPLICATION_CREDENTIALS` environment variable or use an attached service account—not this command.
- ✓
gcloud auth activate-service-account --key-file=KEY_FILE
Why this is correct
The command `gcloud auth activate-service-account --key-file=KEY_FILE` is the correct way to authenticate gcloud with a service account using its private key JSON file. It reads the key file, derives the service account email, and establishes that identity as the active authenticated account for gcloud CLI operations. This command both authenticates and activates the service account in one step, enabling subsequent gcloud commands to inherit that identity.
Go deeper
Related to this question
Learn chapter
Google Cloud Platform Overview
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.
Key term
Service account
A service account is a special type of account used by an application or a virtual machine, rather than a human user, to authenticate and interact with cloud services and APIs securely.
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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.