The answer is using a service account key file with `gcloud auth activate-service-account`, along with `gcloud auth login` and application default credentials. These three methods are valid because the Google Cloud SDK authenticates Cloud Function deployments by verifying that the active credentials possess the `cloudfunctions.functions.create` and `iam.serviceAccounts.actAs` permissions, which can be granted to either a user account via OAuth 2.0 or a service account via a JSON key file. On the Google Professional Cloud Developer exam, this question tests your understanding of how the SDK resolves credentials—it checks the `GOOGLE_APPLICATION_CREDENTIALS` environment variable first, then the active gcloud account, and finally the metadata server. A common trap is thinking that `gcloud auth application-default login` alone suffices for deployments; in reality, it sets ADC for client libraries, not for gcloud commands. Remember the mnemonic “Key, Login, ADC” to recall the three valid paths: service account key, user login, and application default credentials.
PCD Deploying applications Practice Question
This PCD practice question tests your understanding of deploying applications. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which THREE are valid methods for authenticating a user or service when deploying a Cloud Function via the Google Cloud SDK? (Choose 3)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Using a user account with 'gcloud auth login'
Option B is correct because 'gcloud auth login' authenticates a user account via OAuth 2.0, which is a valid method for deploying Cloud Functions. The Google Cloud SDK uses the user's credentials to authorize API calls, including deployments, making this a standard authentication approach for interactive or user-driven workflows.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Using an API key
Why it's wrong here
API keys are for simple API calls, not for Cloud SDK authentication.
✓
Using a user account with 'gcloud auth login'
Why this is correct
Valid: User accounts can authenticate via OAuth 2.0.
Related concept
Read the scenario before looking for a memorised answer.
✗
Using an OAuth 2.0 client ID
Why it's wrong here
OAuth 2.0 client IDs are for web applications, not for gcloud CLI.
✓
Using an access token obtained from the Google Cloud Console
Why this is correct
Valid: Access tokens can be used with 'gcloud auth login --access-token' or similar.
Related concept
Read the scenario before looking for a memorised answer.
✓
Using a service account key file with 'gcloud auth activate-service-account'
Why this is correct
Valid: Service account key files are used to authenticate as a service account.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between authentication methods that are valid for SDK commands versus those meant for other contexts, such as API keys for simple API access or OAuth client IDs for application flows, leading candidates to mistakenly select them as valid for gcloud deployments.
Detailed technical explanation
How to think about this question
Under the hood, 'gcloud auth login' initiates an OAuth 2.0 flow that stores a refresh token and access token in the SDK's credential store, which is then used to authenticate subsequent API calls. Service account key files (Option E) use a JSON key containing a private key to generate JWT assertions for OAuth 2.0 token exchange, enabling non-interactive deployments. Access tokens from the Google Cloud Console (Option D) are short-lived and can be passed via the 'Authorization' header or used with 'gcloud auth print-access-token' for immediate deployment tasks.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Deploying applications — This question tests Deploying applications — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Using a user account with 'gcloud auth login' — Option B is correct because 'gcloud auth login' authenticates a user account via OAuth 2.0, which is a valid method for deploying Cloud Functions. The Google Cloud SDK uses the user's credentials to authorize API calls, including deployments, making this a standard authentication approach for interactive or user-driven workflows.
What should I do if I get this PCD question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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