Declarative vs Imperative way of creating Kubernetes objects

ByJerry Richard

There are 2 ways to create an object in a Kubernetes cluster, either imperative or declarative. Let’s see a few simple examples to understand these two ways.

Imperative:

The imperative way is basically to create Kubernetes objects using direct kubectl commands

Let’s try creating a pod, deployment, and services using the imperative way

Create a Pod

kubectl run nginx --image=nginx

Create a deployment

kubectl create deployment --image=nginx nginx

Create a Service

kubectl expose pod redis --port=6489 --name service --dry-run=client -o yaml

We can even generate definition files using commands (This would help you better in certification exam)

kubectl create deployment nginx --image=nginx --dry-run=client -o yaml > deployment.yaml

Then we can add needed information in the definition files to create the object

Declarative:

Creating Kubernetes object using definition files (YAML). Let us try to make a pod using a declarative way

Create a YAML file with pod definition:

apiVersion: v1
kind: Pod
metadata:
  name: nginx
spec:
  containers:
  - name: nginx
    image: nginx
    ports:
    - containerPort: 80

Remember, You don’t need to remember this definition and syntax for creating a YAML file. You can just visit “kubernetes.io” -> Seach for pod -> Get the pod definition YAML file and create the object

kubectl create -f <pod_definition.yaml>
kubectl apply -f <pod_definition.yaml>

This is similar to all other Kubernetes objects like Service, deployment, pod, etc. It is necessary to learn both ways and use them accordingly. Checkout

Reference: https://kubernetes.io/docs/reference/kubectl/conventions/

Check here for more Kubernetes certification tips

Jerry Richard

Jerry grew up in a small town where he enjoyed playing video games. Once out of the nest, he pursued a Bachelor's degree in Computer Engineering. After college, he ultimately landed in the IT industry. Currently, he has over 10 years of experience. In his spare time, Jerry enjoys spending time with his family.

He is creator of this website - learnerkb.com, A website dedicated to share the mistake and experience learned.

Check my bio for more information About Me

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