Service accounts in Kubernetes - Mini Project: Build & Apply

Kubernetes Service Accounts Setup

📖 Scenario: You are managing a Kubernetes cluster for a small team. You want to create a service account to allow a pod to access the Kubernetes API securely without using the default service account.

🎯 Goal: Learn how to create a Kubernetes service account, configure it, and verify it is correctly set up for use by pods.

📋 What You'll Learn

Create a service account named my-service-account in the default namespace

Add a label app: demo to the service account

List the service accounts in the default namespace to verify creation

Display the details of the created service account

💡 Why This Matters

🌍 Real World

Service accounts let pods securely access the Kubernetes API without using user credentials. This is important for automation and security.

💼 Career

Understanding service accounts is essential for Kubernetes administrators and DevOps engineers to manage permissions and secure workloads.

1

Create a service account

Create a Kubernetes service account named my-service-account in the default namespace using kubectl.

Kubernetes

# Use kubectl to create the service account
# Your code here

Hint

Use the kubectl create serviceaccount command with the --namespace option.

2

Add a label to the service account

Add a label app=demo to the service account my-service-account in the default namespace using kubectl.

Kubernetes

kubectl create serviceaccount my-service-account --namespace=default
# Add label app=demo to my-service-account
# Your code here

Hint

Use kubectl label serviceaccount with the service account name and label key-value.

3

List service accounts to verify

List all service accounts in the default namespace using kubectl to verify that my-service-account exists.

Kubernetes

kubectl create serviceaccount my-service-account --namespace=default
kubectl label serviceaccount my-service-account app=demo --namespace=default
# List service accounts in default namespace
# Your code here

Hint

Use kubectl get serviceaccounts with the --namespace option.

4

Show details of the service account

Display detailed information about the service account my-service-account in the default namespace using kubectl.

Kubernetes

kubectl get serviceaccounts --namespace=default
# Show detailed info of my-service-account
# Your code here

Hint

Use kubectl describe serviceaccount with the service account name and namespace.

Practice

1. What is the main purpose of a ServiceAccount in Kubernetes?

easy

A. To schedule pods on specific nodes

B. To give a pod an identity and control its permissions inside the cluster

C. To manage network policies between pods

D. To store container images for pods

Solution

1. Step 1: Understand what identity means in Kubernetes

   A ServiceAccount provides an identity for pods so they can authenticate to the Kubernetes API.

2. Step 2: Recognize the role of permissions

   ServiceAccounts are linked to permissions (via Roles or ClusterRoles) to control what pods can do.

3. Final Answer:

   To give a pod an identity and control its permissions inside the cluster -> Option B

4. Quick Check:

   ServiceAccount = Pod identity and permissions [OK]

Hint: ServiceAccount = pod identity + permissions [OK]

Common Mistakes:

• Confusing ServiceAccount with image storage
• Thinking ServiceAccount manages pod scheduling
• Mixing ServiceAccount with network policies

2. Which of the following is the correct YAML snippet to create a ServiceAccount named my-service-account?

easy

A. apiVersion: apps/v1
kind: Deployment
metadata:
name: my-service-account

B. apiVersion: v1
kind: Pod
metadata:
name: my-service-account

C. apiVersion: v1
kind: ServiceAccount
metadata:
name: my-service-account

D. apiVersion: v1
kind: Namespace
metadata:
name: my-service-account

Solution

1. Step 1: Identify the correct kind for ServiceAccount

   The kind must be ServiceAccount to create a service account resource.

2. Step 2: Check the apiVersion and metadata

   ServiceAccount uses apiVersion: v1 and metadata with the name field.

3. Final Answer:

   apiVersion: v1 kind: ServiceAccount metadata: name: my-service-account -> Option C

4. Quick Check:

   ServiceAccount YAML uses kind: ServiceAccount [OK]

Hint: ServiceAccount YAML always uses kind: ServiceAccount [OK]

Common Mistakes:

• Using wrong kind like Pod or Deployment
• Wrong apiVersion for ServiceAccount
• Confusing Namespace with ServiceAccount

3. Given this command: kubectl get serviceaccount default -o jsonpath='{.secrets[0].name}', what does it output?

medium

A. The name of the first secret linked to the default ServiceAccount

B. The list of all pods using the default ServiceAccount

C. The token value inside the secret

D. An error because jsonpath is invalid

Solution

1. Step 1: Understand the command structure

   The command fetches the ServiceAccount named 'default' and extracts the first secret's name using jsonpath.

2. Step 2: Interpret the jsonpath expression

   The expression {.secrets[0].name} selects the name of the first secret linked to the ServiceAccount.

3. Final Answer:

   The name of the first secret linked to the default ServiceAccount -> Option A

4. Quick Check:

   jsonpath extracts secret name from ServiceAccount [OK]

Hint: jsonpath {.secrets[0].name} gets first secret name [OK]

Common Mistakes:

• Thinking it lists pods instead of secrets
• Expecting secret token value instead of secret name
• Assuming jsonpath syntax is wrong

4. You created a ServiceAccount but your pod fails to use it. Which of these is the most likely cause?

medium

A. The ServiceAccount was created in a different namespace

B. The pod image is missing

C. The ServiceAccount has no secrets linked

D. The pod spec does not specify the ServiceAccount name

Solution

1. Step 1: Check namespace consistency

   ServiceAccounts are namespace-scoped. If the pod is in one namespace but the ServiceAccount in another, the pod cannot use it.

2. Step 2: Verify pod spec and ServiceAccount existence

   Even if the ServiceAccount exists in the same namespace, the pod must specify the ServiceAccount name in its spec to use it.

3. Final Answer:

   The pod spec does not specify the ServiceAccount name -> Option D

4. Quick Check:

   Pod spec must specify serviceAccountName to use it [OK]

Hint: Pod spec must specify serviceAccountName [OK]

Common Mistakes:

• Forgetting to specify serviceAccountName in pod spec
• Assuming missing secrets cause pod failure
• Blaming pod image unrelated to ServiceAccount

5. You want a pod to use a custom ServiceAccount named app-sa and access the Kubernetes API with limited permissions. Which steps should you follow?

hard

A. Create the ServiceAccount app-sa, create a Role with permissions, bind the Role to app-sa, then specify serviceAccountName: app-sa in the pod spec

B. Create a RoleBinding for the default ServiceAccount, then deploy the pod without specifying serviceAccountName

C. Create a ClusterRole with full permissions and assign it to the pod directly

D. Deploy the pod first, then create the ServiceAccount and Role

Solution

1. Step 1: Create the custom ServiceAccount

   Define and create app-sa in the pod's namespace to give the pod an identity.

2. Step 2: Define permissions and bind them

   Create a Role with limited permissions and bind it to app-sa using a RoleBinding.

3. Step 3: Specify the ServiceAccount in the pod spec

   Set serviceAccountName: app-sa in the pod spec so the pod uses this identity and permissions.

4. Final Answer:

   Create the ServiceAccount app-sa, create a Role with permissions, bind the Role to app-sa, then specify serviceAccountName: app-sa in the pod spec -> Option A

5. Quick Check:

   Custom ServiceAccount + Role + RoleBinding + pod spec = correct setup [OK]

Hint: Create SA, Role, RoleBinding, then assign SA to pod [OK]

Common Mistakes:

• Assigning permissions to default ServiceAccount instead of custom
• Creating ClusterRole with too many permissions
• Deploying pod before creating ServiceAccount and Role