Day 32 Launching your Kubernetes Cluster with Deployment

What is Pod in k8s?

A Pod (as in a pod of whales or pea pod) is a group of one or more containers, with shared storage and network resources, and a specification for how to run the containers. A Pod's contents are always co-located and co-scheduled, and run in a shared context. A Pod models an application-specific "logical host": it contains one or more application containers that are relatively tightly coupled. In non-cloud contexts, applications executed on the same physical or virtual machine are analogous to cloud applications executed on the same logical host.

What is Deployment in k8s?

A Deployment provides declarative updates for Pods and ReplicaSets.

You describe a desired state in a Deployment, and the Deployment Controller changes the actual state to the desired state at a controlled rate. You can define Deployments to create new ReplicaSets or to remove existing Deployments and adopt all their resources with new Deployments.

Here are the key aspects of a Kubernetes Deployment:

1. Desired State

2. Rolling Updates and Rollbacks

3. Scaling

4. High Availability

5. Self-healing

Task:

Create one Deployment file to deploy a sample todo-app on K8s using the "Auto-healing" and "Auto-Scaling" feature

First set up the Kubernetes cluster with the master node and the worker node.

now create a manifest file for our nodo-todo application

apiVersion: apps/v1
kind: Deployment
metadata:
  name: todo-app
  labels:
    app: todo
spec:
  replicas: 2
  selector:
    matchLabels:
      app: todo
  template:
    metadata:
      labels:
        app: todo
    spec:
      containers:
      - name: todo
        image: rishikeshops/todo-app
        ports:
        - containerPort: 3000

Create the deployment using kubectl apply -f todo-deployment.yml

Scale the replicas of deployment if required

Here I have scaled the replicas to 2,

using
kubectl scale --replicas=2 deploy/todo-deployment.yml

So I encourage you to try this on your own and let me know in the comment section about your learning experience

Thank you for reading!

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