kubectl apply vs create in Kubernetes - Hands-On Comparison

Understanding kubectl apply vs create

📖 Scenario: You are managing a Kubernetes cluster. You want to deploy an application using YAML files. You need to understand the difference between kubectl create and kubectl apply commands to manage your resources effectively.

🎯 Goal: Learn how to create a Kubernetes deployment using kubectl create and then update it using kubectl apply. See how these commands behave differently when managing resource changes.

📋 What You'll Learn

Create a Kubernetes deployment YAML file named nginx-deployment.yaml with specified content

Use kubectl create to create the deployment from the YAML file

Modify the YAML file to change the number of replicas

Use kubectl apply to update the deployment with the new replica count

Observe the output of both commands

💡 Why This Matters

🌍 Real World

Kubernetes is widely used to deploy and manage containerized applications. Knowing how to create and update resources with kubectl commands is essential for daily cluster operations.

💼 Career

DevOps engineers and site reliability engineers use these commands to manage application deployments, updates, and rollbacks in production environments.

1

Create the initial deployment YAML file

Create a file named nginx-deployment.yaml with the exact content below:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80

Kubernetes

# Create the file nginx-deployment.yaml with the exact content
# Your code here

Hint

Use a text editor to create nginx-deployment.yaml with the exact YAML content.

2

Create the deployment using kubectl create

Run the command kubectl create -f nginx-deployment.yaml to create the deployment in your Kubernetes cluster.

Kubernetes

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80

# Run kubectl create command below
# Your code here

Hint

Type exactly kubectl create -f nginx-deployment.yaml to create the deployment.

3

Modify the deployment YAML to change replicas

Edit the nginx-deployment.yaml file to change the replicas value from 2 to 3.

Kubernetes

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80

# Change replicas from 2 to 3 below
# Your code here

Hint

Open the YAML file and change the line replicas: 2 to replicas: 3.

4

Update the deployment using kubectl apply

Run the command kubectl apply -f nginx-deployment.yaml to update the deployment with the new replica count. Then run kubectl get deployment nginx-deployment to see the updated replicas.

Kubernetes

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80

# Run kubectl apply and then kubectl get deployment commands below
# Your code here

Hint

Type exactly kubectl apply -f nginx-deployment.yaml and then kubectl get deployment nginx-deployment.

Practice

1. What is the main difference between kubectl create and kubectl apply?

easy

A. kubectl create only creates new resources and fails if they exist; kubectl apply creates or updates resources.

B. kubectl create updates existing resources; kubectl apply deletes resources.

C. kubectl create deletes resources; kubectl apply only creates new resources.

D. kubectl create and kubectl apply do the same thing.

Solution

1. Step 1: Understand kubectl create behavior

   kubectl create makes new resources but will fail if the resource already exists.

2. Step 2: Understand kubectl apply behavior

   kubectl apply can create new resources or update existing ones safely without failing.

3. Final Answer:

   kubectl create only creates new resources and fails if they exist; kubectl apply creates or updates resources. -> Option A

4. Quick Check:

   create = new only, apply = create or update [OK]

Hint: Create fails if exists; apply updates or creates [OK]

Common Mistakes:

• Thinking create updates existing resources
• Believing apply deletes resources
• Assuming both commands behave identically

2. Which of the following is the correct syntax to create a deployment using kubectl create?

easy

A. kubectl create deployment myapp --image=nginx

B. kubectl create pod myapp --image=nginx

C. kubectl apply deployment myapp --image=nginx

D. kubectl apply -f deployment.yaml

Solution

1. Step 1: Identify kubectl create syntax for deployment

   The command kubectl create deployment myapp --image=nginx creates a deployment named myapp with the nginx image.

2. Step 2: Differentiate from kubectl apply syntax

   kubectl apply uses the -f flag with a file, not direct deployment creation.

3. Final Answer:

   kubectl create deployment myapp --image=nginx -> Option A

4. Quick Check:

   create deployment uses direct command, apply uses files [OK]

Hint: Use 'create deployment' with image flag, apply uses files [OK]

Common Mistakes:

• Using apply syntax with create command
• Mixing file flag with create deployment
• Confusing create and apply commands

3. Given the commands below, what will happen if the deployment myapp already exists?

kubectl create deployment myapp --image=nginx
kubectl apply -f deployment.yaml

medium

A. Both commands will fail because the deployment exists.

B. Both commands will update the deployment.

C. The create command will update; the apply command will fail.

D. The create command will fail; the apply command will update the deployment.

Solution

1. Step 1: Behavior of kubectl create on existing resource

   kubectl create fails if the resource already exists, so the first command will fail.

2. Step 2: Behavior of kubectl apply on existing resource

   kubectl apply updates the existing resource safely, so the second command updates the deployment.

3. Final Answer:

   The create command will fail; the apply command will update the deployment. -> Option D

4. Quick Check:

   create fails if exists; apply updates [OK]

Hint: Create fails if exists; apply updates existing resources [OK]

Common Mistakes:

• Assuming create updates existing resources
• Thinking apply fails if resource exists
• Believing both commands behave the same

4. You ran kubectl create -f service.yaml but got an error saying the service already exists. What should you do to update the service instead?

medium

A. Use kubectl replace -f service.yaml to update the service.

B. Delete the service first, then run kubectl create -f service.yaml again.

C. Use kubectl apply -f service.yaml to update the existing service.

D. Run kubectl create -f service.yaml with a different name.

Solution

1. Step 1: Understand the error cause

   kubectl create fails if the resource exists, so the error means the service is already present.

2. Step 2: Choose the correct update method

   kubectl apply safely updates existing resources without deleting them, so use kubectl apply -f service.yaml.

3. Final Answer:

   Use kubectl apply -f service.yaml to update the existing service. -> Option C

4. Quick Check:

   apply updates existing resources safely [OK]

Hint: Use apply to update existing resources, not create [OK]

Common Mistakes:

• Trying to create again without deleting
• Deleting resources unnecessarily
• Using replace without understanding its effect

5. You want to manage a deployment over time, updating its image and replicas safely without deleting it. Which command should you use and why?

hard

A. Use kubectl create deployment myapp --image=nginx repeatedly to update the deployment.

B. Use kubectl apply -f deployment.yaml because it creates or updates resources safely.

C. Use kubectl delete deployment myapp then kubectl create -f deployment.yaml to update.

D. Use kubectl replace -f deployment.yaml because it creates new resources.

Solution

1. Step 1: Identify the need for safe updates over time

   Managing a deployment means updating it multiple times without deleting or failing.

2. Step 2: Choose the command that supports create or update safely

   kubectl apply can create or update resources safely, preserving existing settings and avoiding errors.

3. Step 3: Evaluate other options

   kubectl create fails if resource exists; deleting is disruptive; replace overwrites but is less safe than apply.

4. Final Answer:

   Use kubectl apply -f deployment.yaml because it creates or updates resources safely. -> Option B

5. Quick Check:

   Manage resources over time with apply [OK]

Hint: Apply manages updates safely; create is one-time only [OK]

Common Mistakes:

• Using create repeatedly causing errors
• Deleting resources unnecessarily
• Confusing replace with apply