Google ACE Configuring Access and Security Practice Question
An engineer needs to grant a service account the ability to impersonate another service account when making API calls. Which IAM role should be assigned to the impersonating service account?
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
✓
roles/iam.serviceAccountUser
The roles/iam.serviceAccountUser role allows a principal to impersonate a service account (by getting an access token for that account). roles/iam.serviceAccountTokenCreator allows creating tokens but not full impersonation. roles/serviceusage.serviceUsageConsumer is for service usage, not impersonation. roles/iam.serviceAccountAdmin allows administrative actions but not impersonation.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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roles/iam.serviceAccountAdmin
Why it's wrong here
roles/iam.serviceAccountAdmin grants administrative permissions to create, update, delete, and manage IAM policies on service accounts, but it does not include iam.serviceAccounts.actAs or iam.serviceAccounts.implicitDelegation. This means the holder can manage the service account's lifecycle and permissions yet cannot assume its identity or use it to access other cloud resources. Therefore, while a powerful role for governance, it is the wrong choice when the goal is to grant the ability to act on behalf of the service account.
- ✗
roles/serviceusage.serviceUsageConsumer
Why it's wrong here
roles/serviceusage.serviceUsageConsumer is intended for inspecting and using enabled Google Cloud services, such as listing services, viewing quotas, and enabling/disabling services in some cases. It has no permissions on service accounts themselves, nor does it include any token generation or identity delegation capabilities. This role cannot be used to impersonate a service account or obtain credentials; it only governs interactions with the Service Usage API.
- ✓
roles/iam.serviceAccountUser
Why this is correct
roles/iam.serviceAccountUser is the correct role because it includes the permissions iam.serviceAccounts.actAs and iam.serviceAccounts.implicitDelegation. The actAs permission allows a principal to use the service account to access resources and create resources that are owned by or signed with the service account's identity. ImplicitDelegation also permits the principal to impersonate service accounts that are arranged in a delegated chain, making this the minimal standard role for granting a service account the ability to act on behalf of another entity.
- ✗
roles/iam.serviceAccountTokenCreator
Why it's wrong here
roles/iam.serviceAccountTokenCreator permits the holder to generate short-lived OAuth2 access tokens, sign blobs, and sign JWTs for the service account via permissions like iam.serviceAccounts.getAccessToken and iam.serviceAccounts.signBlob. However, it does not include iam.serviceAccounts.actAs, so it allows token creation but not the full act of impersonation in the context of starting compute resources, deploying serverless functions, or other operations where the service account's identity is assigned to a resource. It is a narrower, token-specific role and is not sufficient for general service account usage.
Go deeper
Related to this question
Learn chapter
GCP IAM and Service Accounts
Key term
IAM
Identity and Access Management (IAM) is a framework of policies and technologies that ensures the right individuals have the appropriate access to technology resources.
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.