Creating Deployments with YAML in Kubernetes - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the kind of Kubernetes object.

Kubernetes

apiVersion: apps/v1
kind: [1]
metadata:
  name: my-deployment

Drag options to blanks, or click blank then click option'

AConfigMap

BService

CDeployment

DPod

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Pod' instead of 'Deployment' will create a single pod, not a deployment.

Using 'Service' will create a network endpoint, not a deployment.

The kind field defines the type of Kubernetes object. For creating deployments, it must be Deployment.

2fill in blank

medium

Complete the code to set the number of pod replicas.

Kubernetes

spec:
  replicas: [1]
  selector:
    matchLabels:
      app: myapp

Drag options to blanks, or click blank then click option'

A3

Bten

Czero

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using words like 'ten' instead of numbers causes errors.

Negative numbers are not allowed for replicas.

The replicas field specifies how many pod copies to run. It must be a positive integer like 3.

3fill in blank

hard

Fix the error in the container image name.

Kubernetes

containers:
- name: myapp-container
  image: [1]

Drag options to blanks, or click blank then click option'

Anginx/latest

Bnginx:latest

Cnginx latest

Dnginx_latest

Attempts:

3 left

💡 Hint

Common Mistakes

Using slash '/' instead of colon ':' causes image pull errors.

Using spaces in image names is invalid.

The container image name must use a colon : to separate the image name and tag, like nginx:latest.

4fill in blank

hard

Fill both blanks to correctly specify container ports and labels.

Kubernetes

spec:
  template:
    metadata:
      labels:
        app: [1]
    spec:
      containers:
      - name: myapp-container
        image: nginx:latest
        ports:
        - containerPort: [2]

Drag options to blanks, or click blank then click option'

Amyapp

B80

C8080

Dwebapp

Attempts:

3 left

💡 Hint

Common Mistakes

Using different labels breaks pod selection.

Using wrong port numbers causes connection issues.

The label app should match the selector label, here myapp. The common HTTP port for nginx is 80.

5fill in blank

hard

Fill all three blanks to complete the deployment spec with correct keys and values.

Kubernetes

apiVersion: apps/v1
kind: Deployment
metadata:
  name: [1]
spec:
  replicas: [2]
  selector:
    matchLabels:
      app: [3]

Drag options to blanks, or click blank then click option'

Amy-deployment

B3

Cmyapp

Ddefault

Attempts:

3 left

💡 Hint

Common Mistakes

Mismatched labels cause deployment to fail selecting pods.

Using zero or negative replicas stops pods from running.

The deployment name is my-deployment. The replicas count is 3. The label app must match the pod template label, here myapp.

Practice

1. What is the main purpose of a Deployment in Kubernetes when defined using a YAML file?

easy

A. To manage and update multiple copies of an application smoothly

B. To store data persistently across pods

C. To expose an application to the internet

D. To define network policies between pods

Solution

1. Step 1: Understand Deployment role

   A Deployment manages the lifecycle of pods, ensuring the desired number of replicas run and updates happen smoothly.

2. Step 2: Compare options

   Options B, C, and D describe other Kubernetes resources (PersistentVolume, Service, NetworkPolicy), not Deployment.

3. Final Answer:

   To manage and update multiple copies of an application smoothly -> Option A

4. Quick Check:

   Deployment = Manage app replicas and updates [OK]

Hint: Deployments control app copies and updates, not storage or networking [OK]

Common Mistakes:

• Confusing Deployment with Service or PersistentVolume
• Thinking Deployment exposes apps externally
• Assuming Deployment manages network policies

2. Which of the following YAML snippets correctly sets the number of pod replicas to 3 in a Deployment?

easy

A. replicas: 3

B. replicaCount: 3

C. count: 3

D. podReplicas: 3

Solution

1. Step 1: Identify correct replicas field

   The correct field to specify pod count in Deployment YAML is replicas.

2. Step 2: Check other options

   Fields like replicaCount, count, or podReplicas are invalid and will cause errors.

3. Final Answer:

   replicas: 3 -> Option A

4. Quick Check:

   Use 'replicas' to set pod count [OK]

Hint: Use 'replicas' exactly to set pod count in Deployment YAML [OK]

Common Mistakes:

• Using incorrect field names like replicaCount
• Misspelling 'replicas' or using camelCase
• Placing replicas under wrong YAML level

3. Given this Deployment YAML snippet, what will be the label selector used to match pods?

selector:
  matchLabels:
    app: myapp
    tier: frontend

medium

A. Pods with any label app or tier

B. Pods with label app=myapp only

C. Pods with label tier=frontend only

D. Pods with labels app=myapp and tier=frontend

Solution

1. Step 1: Understand matchLabels selector

   The matchLabels requires all listed labels to match exactly for pod selection.

2. Step 2: Analyze given labels

   Both app: myapp and tier: frontend must be present on pods to match.

3. Final Answer:

   Pods with labels app=myapp and tier=frontend -> Option D

4. Quick Check:

   matchLabels means all labels must match [OK]

Hint: matchLabels requires all labels to match exactly [OK]

Common Mistakes:

• Assuming matchLabels matches any one label
• Confusing matchLabels with matchExpressions
• Ignoring one of the labels in selector

4. You wrote this Deployment YAML but your pods are not created. What is the error?

apiVersion: apps/v1
kind: Deployment
metadata:
  name: webapp
spec:
  replicas: 2
  selector:
    matchLabels:
      app: webapp
  template:
    metadata:
      labels:
        app: frontend
    spec:
      containers:
      - name: webapp
        image: nginx

medium

A. No container ports defined

B. Incorrect apiVersion for Deployment

C. Selector labels do not match template labels

D. Missing container image tag

Solution

1. Step 1: Check selector and template labels

   The selector matchLabels: app: webapp does not match template labels: app: frontend. Labels must match exactly or Deployment creation fails.

2. Step 2: Verify other fields

   Ports are optional for pod creation; apiVersion is correct; image tag defaults to latest.

3. Final Answer:

   Selector labels do not match template labels -> Option C

4. Quick Check:

   Selector must match template labels [OK]

Hint: Selector labels must exactly match template labels [OK]

Common Mistakes:

• Assuming container ports are required for pod creation
• Thinking image tag is mandatory
• Confusing apiVersion for Deployment

5. You want to update your Deployment to run 5 replicas and change the container image to 'nginx:1.21'. Which YAML snippet correctly applies both changes?

hard

A. spec:
replicas: 5
template:
spec:
containers:
- name: nginx
image: nginx:1.21

B. spec:
replicas: 5
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.21

C. spec:
replicas: 5
containers:
- name: nginx
image: nginx:1.21

D. spec:
template:
spec:
containers:
- name: nginx
image: nginx:1.21
replicas: 5

Solution

1. Step 1: Understand Deployment spec structure

   The replicas field is directly under spec. The pod template is under spec.template, which must include metadata.labels and spec.containers.

2. Step 2: Check each option's correctness

   spec:
     replicas: 5
     template:
       spec:
         containers:
         - name: nginx
           image: nginx:1.21

   misses metadata.labels under template, which is required for selector matching.

   spec:
     replicas: 5
     containers:
     - name: nginx
       image: nginx:1.21

   places containers directly under spec, which is invalid.

   spec:
     template:
       spec:
         containers:
         - name: nginx
           image: nginx:1.21
     replicas: 5

   places replicas after template, which is allowed but missing labels in template metadata.

   spec:
     replicas: 5
     template:
       metadata:
         labels:
           app: nginx
       spec:
         containers:
         - name: nginx
           image: nginx:1.21

   correctly includes replicas, template metadata labels, and container spec with updated image.

3. Final Answer:

   spec: replicas: 5, template with metadata.labels app: nginx, containers image: nginx:1.21 -> Option B

4. Quick Check:

   replicas under spec, labels in template metadata, containers in template spec [OK]

Hint: Always include labels in template metadata for selector matching [OK]

Common Mistakes:

• Omitting labels in pod template metadata
• Placing containers outside template spec
• Misplacing replicas field