Service accounts for applications in GCP - Step-by-Step Execution

Process Flow - Service accounts for applications

Create Service Account

↓

Assign Roles/Permissions

↓

Application Uses Service Account

↓

Service Account Authenticates

↓

Access GCP Resources

↓

Perform Allowed Actions

↓

End

This flow shows how a service account is created, given permissions, then used by an application to access GCP resources securely.

Execution Sample

GCP

gcloud iam service-accounts create app-sa --display-name="App Service Account"
gcloud projects add-iam-policy-binding my-project --member="serviceAccount:[e-mail]" --role="roles/storage.objectViewer"
# Application uses app-sa key to authenticate and access storage

Create a service account, assign it a role to view storage objects, then the application uses it to access storage.

Process Table

Step	Action	Resource Affected	Result	Notes
1	Create service account 'app-sa'	IAM Service Accounts	Service account 'app-sa' created	Ready for permission assignment
2	Assign 'storage.objectViewer' role to 'app-sa'	IAM Policy Binding	Role assigned to 'app-sa'	Allows read access to storage objects
3	Application authenticates using 'app-sa' credentials	Authentication	Authentication successful	App can now act as 'app-sa'
4	Application requests storage object list	Cloud Storage	Access granted, object list returned	Permission check passed
5	Application tries to delete storage object	Cloud Storage	Access denied	No delete permission assigned
6	End	-	Execution stops	Application limited by assigned roles

💡 Execution stops because application only has read permission, no further actions allowed.

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5	Final
Service Account 'app-sa'	Not created	Created	Created with role	Authenticated	Authenticated	Authenticated	Authenticated
Permissions	None	None	storage.objectViewer	storage.objectViewer	storage.objectViewer	storage.objectViewer	storage.objectViewer
Application Access	None	None	None	Allowed to read storage	Allowed to read storage	Denied delete storage	Denied delete storage

Key Moments - 2 Insights

Why can't the application delete storage objects even though it uses the service account?

Because the service account was only given the 'storage.objectViewer' role, which allows read-only access. This is shown in execution_table step 5 where delete is denied.

What happens if the service account is not assigned any role?

The application cannot access any resources because the service account has no permissions. This is implied before step 2 in the execution_table.

Visual Quiz - 3 Questions

Look at the execution table, at which step does the application successfully authenticate using the service account?

A Step 2

B Step 3

C Step 4

D Step 5

💡 Hint

Check the 'Result' column for authentication success in the execution_table.

According to the variable tracker, what permission does the service account have after step 2?

A storage.admin

B No permissions

C storage.objectViewer

D storage.objectCreator

💡 Hint

Look at the 'Permissions' row after step 2 in the variable_tracker.

If the application needed to delete storage objects, what change would you make in the execution table?

A Assign 'storage.objectAdmin' role to the service account

B Remove the service account

C Change authentication method

D No change needed

💡 Hint

Refer to step 5 where delete is denied due to insufficient permissions.

Concept Snapshot

Service accounts are special accounts for applications to access GCP resources.
Create a service account, assign roles to grant permissions.
Applications authenticate using service account credentials.
Permissions control what actions the app can perform.
Least privilege: assign only needed roles for security.

Full Transcript

Service accounts let applications securely access Google Cloud resources. First, create a service account. Then assign it roles that define what it can do, like reading storage objects. The application uses the service account's credentials to authenticate. Once authenticated, the app can perform actions allowed by the assigned roles. For example, if the service account has only read permissions, the app cannot delete storage objects. This keeps access secure and limited to what is necessary.

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