Service accounts for applications in GCP - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding service account roles

You have an application running on Google Cloud that needs to read data from a Cloud Storage bucket but should not modify or delete any data. Which service account role should you assign to the application?

A roles/storage.admin

B roles/storage.objectAdmin

C roles/storage.objectViewer

D roles/owner

💡 Hint

Think about the principle of least privilege: only allow what is necessary.

The roles/storage.objectViewer role allows read-only access to objects in Cloud Storage buckets. It fits the requirement to read data without modifying or deleting it. Other roles provide broader permissions than needed.

❓ Configuration

intermediate

Service account key management

You want to securely provide your application running outside Google Cloud access to a Google Cloud API using a service account. Which method is the best practice for managing the service account key?

A Store the service account key in a secure secret manager and load it at runtime.

B Download the service account JSON key once and embed it directly in the application code.

C Create a new service account key every time the application starts.

D Share the service account key via email to all developers.

💡 Hint

Think about how to keep secrets safe and avoid exposing keys unnecessarily.

Storing the service account key in a secure secret manager and loading it at runtime is best practice. It avoids hardcoding secrets and reduces risk of exposure. Downloading and embedding keys or sharing via email are insecure. Creating new keys frequently is inefficient and can cause key sprawl.

❓ Architecture

advanced

Designing least privilege for multi-service application

You have a multi-service application on Google Cloud. Service A needs to write logs to Cloud Logging. Service B needs to read messages from a Pub/Sub subscription. Both services use separate service accounts. Which is the best way to assign permissions?

A Assign roles/logging.logWriter to Service A's service account and roles/pubsub.subscriber to Service B's service account.

B Assign roles/editor to both service accounts to cover all permissions.

C Assign roles/logging.admin to Service A's service account and roles/pubsub.admin to Service B's service account.

D Assign roles/owner to Service A's service account and roles/pubsub.viewer to Service B's service account.

💡 Hint

Remember to give only the permissions each service needs.

Assigning roles/logging.logWriter to Service A and roles/pubsub.subscriber to Service B follows the principle of least privilege. Using broad roles like editor or owner grants unnecessary permissions and increases security risk. Admin roles provide more permissions than needed.

❓ security

advanced

Detecting compromised service account keys

You suspect a service account key has been compromised. What is the immediate best action to secure your Google Cloud environment?

A Change the service account's password.

B Delete the service account entirely to revoke all access.

C Disable the service account temporarily without deleting keys.

D Rotate the compromised key by deleting it and creating a new key, then update applications.

💡 Hint

Think about how to stop unauthorized access quickly while minimizing disruption.

Rotating the compromised key by deleting it and creating a new one immediately stops unauthorized use of the old key. Deleting the entire service account can cause service disruption. Disabling the account may not revoke keys immediately. Service accounts do not have passwords.

❓ service_behavior

expert

Service account token expiration behavior

An application running on Google Compute Engine uses a service account to access Google Cloud APIs. The application obtains an access token from the metadata server. What happens when the access token expires?

A The application must manually request a new access token from the metadata server to continue API calls.

B The metadata server automatically refreshes the access token, and the application can request a new token anytime without credentials.

C The application must restart the VM to get a new access token.

D The access token never expires while the VM is running.

💡 Hint

Think about how Google Cloud manages tokens for VM service accounts.

The metadata server automatically refreshes access tokens for service accounts attached to Compute Engine VMs. Applications can request new tokens anytime without needing to manage credentials manually. Tokens do expire, but the refresh is seamless. Restarting the VM is not required.

Practice

1. What is the main purpose of a service account in Google Cloud Platform (GCP)?

easy

A. To allow applications to authenticate and access GCP resources securely

B. To create user accounts for people to log in to GCP Console

C. To store data in Google Cloud Storage buckets

D. To monitor network traffic between virtual machines

Solution

1. Step 1: Understand service account role

   A service account is a special account used by applications or virtual machines to authenticate and access Google Cloud resources securely without user intervention.

2. Step 2: Differentiate from user accounts

   User accounts are for people to log in, while service accounts are for applications or services to act on behalf of users or themselves.

3. Final Answer:

   To allow applications to authenticate and access GCP resources securely -> Option A

4. Quick Check:

   Service account = app authentication [OK]

Hint: Service accounts are for apps, not people [OK]

Common Mistakes:

• Confusing service accounts with user accounts
• Thinking service accounts store data
• Assuming service accounts monitor network

2. Which of the following is the correct way to assign a service account to a Compute Engine VM instance during creation?

easy

A. Use the --service-account flag with gcloud compute instances create

B. Add the service account email to the VM's firewall rules

C. Specify the service account in the VM's startup script

D. Create a user account with the same name as the service account

Solution

1. Step 1: Identify how to assign service accounts to VMs

   The gcloud compute instances create command supports a --service-account flag to specify which service account the VM should use.

2. Step 2: Eliminate incorrect options

   Firewall rules do not assign service accounts, startup scripts do not assign service accounts, and user accounts are unrelated to service account assignment.

3. Final Answer:

   Use the --service-account flag with gcloud compute instances create -> Option A

4. Quick Check:

   Assign service account with --service-account flag [OK]

Hint: Use --service-account flag when creating VM [OK]

Common Mistakes:

• Trying to assign service account via firewall
• Using startup scripts to assign service accounts
• Confusing user accounts with service accounts

3. Consider this Python code snippet using Google Cloud client libraries:

from google.cloud import storage

client = storage.Client()
buckets = list(client.list_buckets())
print(len(buckets))

What must be true for this code to successfully list buckets?

medium

A. The user must be logged in to GCP Console in a browser

B. The environment must have a service account with Storage Viewer role configured

C. The code must run on a VM with no service account assigned

D. No authentication is needed to list buckets

Solution

1. Step 1: Understand authentication requirement

   Google Cloud client libraries require authentication, usually via a service account or user credentials, to access resources like buckets.

2. Step 2: Identify required permissions

   To list buckets, the service account or user must have at least the Storage Viewer role to read bucket metadata.

3. Final Answer:

   The environment must have a service account with Storage Viewer role configured -> Option B

4. Quick Check:

   Service account with Storage Viewer role needed [OK]

Hint: List buckets needs Storage Viewer role on service account [OK]

Common Mistakes:

• Assuming user login in browser is enough
• Running code without any service account
• Thinking no auth is needed for bucket listing

4. You deployed an application on a GCP VM with a service account, but it fails to access Cloud Storage buckets. What is the most likely cause?

medium

A. The service account email is not the same as the VM name

B. The VM does not have an external IP address

C. The application code is missing the Cloud Storage client library import

D. The service account lacks the necessary IAM permissions for Cloud Storage

Solution

1. Step 1: Check service account permissions

   If the application cannot access Cloud Storage, the most common reason is missing IAM permissions on the service account assigned to the VM.

2. Step 2: Rule out other causes

   Lack of external IP does not block access if using private Google access; missing import causes code errors but not permission failures; service account email unrelated to VM name.

3. Final Answer:

   The service account lacks the necessary IAM permissions for Cloud Storage -> Option D

4. Quick Check:

   Missing IAM permissions cause access failure [OK]

Hint: Check IAM roles on service account first [OK]

Common Mistakes:

• Assuming external IP is required for access
• Blaming code imports without error evidence
• Confusing service account email with VM name

5. You want to deploy a serverless application on Cloud Run that accesses a Cloud SQL database securely. Which approach correctly uses a service account to grant least privilege access?

hard

A. Assign the Cloud Run service account the Storage Admin role to access Cloud SQL

B. Use the default Compute Engine service account with Owner role for Cloud Run

C. Create a service account with only Cloud SQL Client role and assign it to the Cloud Run service

D. Create a user account with Cloud SQL Admin role and embed its credentials in the app

Solution

1. Step 1: Identify least privilege principle

   Grant only the permissions needed. For Cloud SQL access, the Cloud SQL Client role is sufficient.

2. Step 2: Assign correct service account to Cloud Run

   Create a dedicated service account with Cloud SQL Client role and assign it to the Cloud Run service to avoid over-permission.

3. Step 3: Eliminate insecure or excessive options

   Using default service account with Owner role is too broad; Storage Admin role is unrelated; embedding user credentials is insecure.

4. Final Answer:

   Create a service account with only Cloud SQL Client role and assign it to the Cloud Run service -> Option C

5. Quick Check:

   Least privilege: Cloud SQL Client role on service account [OK]

Hint: Use least privilege role on dedicated service account [OK]

Common Mistakes:

• Using overly broad Owner role
• Assigning unrelated roles like Storage Admin
• Embedding user credentials in app code