What is deployment

A Deployment in Kubernetes is a resource object that provides declarative updates to applications. It manages the creation and scaling of a set of Pods, ensuring that the desired number of replicas are running at any given time. Deployments allow you to define the desired state of your application, and Kubernetes will automatically manage the underlying Pods to match that state.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: web-app
  labels:
    app: web-app
spec:
  replicas: 3

  selector:
    matchLabels:
      app: web-app

  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 1

  template:
    metadata:
      labels:
        app: web-app
    spec:
      containers:
        - name: web
          image: nginx:1.25-alpine
          ports:
            - containerPort: 80

          resources:
            requests:
              cpu: "100m"
              memory: "128Mi"
            limits:
              cpu: "500m"
              memory: "256Mi"

          readinessProbe:
            httpGet:
              path: /
              port: 80
            initialDelaySeconds: 5
            periodSeconds: 10

          livenessProbe:
            httpGet:
              path: /
              port: 80
            initialDelaySeconds: 15
            periodSeconds: 20