Kubernetes Deployment: how to deploy and manage stateless applications

Deployments Manage Your App Lifecycle

A Deployment is the standard way to run stateless applications on Kubernetes. It owns a ReplicaSet, which owns Pods. You declare the desired state (image version, replica count) in the Deployment — it handles creating and replacing Pods to match.

Creating a Deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  name: web-app
  namespace: production
spec:
  replicas: 3
  selector:
    matchLabels:
      app: web-app
  template:
    metadata:
      labels:
        app: web-app
    spec:
      containers:
      - name: web-app
        image: nginx:1.25
        ports:
        - containerPort: 80
        resources:
          requests:
            memory: "64Mi"
            cpu: "100m"
          limits:
            memory: "128Mi"
            cpu: "200m"

Scaling and Checking Status

# Apply the deployment
kubectl apply -f deployment.yaml

# Scale to 5 replicas
kubectl scale deployment web-app --replicas=5

# Watch rollout progress
kubectl rollout status deployment/web-app

# View rollout history
kubectl rollout history deployment/web-app

Kubernetes updates the Deployment by creating a new ReplicaSet with the new Pod template and gradually scaling it up while scaling the old ReplicaSet down. This is a rolling update — zero downtime by default.