Deployments & Rolling Updates

A Deployment manages a set of identical Pod replicas via a ReplicaSet, ensuring desired pod counts and handling seamless, zero-downtime application updates.

1. Production Deployment Manifest

apiVersion: apps/v1
kind: Deployment
metadata:
  name: api-deployment
spec:
  replicas: 3 # Maintain 3 pod instances across cluster
  selector:
    matchLabels:
      app: api-server
  template:
    metadata:
      labels:
        app: api-server
    spec:
      containers:
        - name: api-container
          image: myusername/api:v1.0
          ports:
            - containerPort: 3000

2. Scaling & Rollout Management Commands

# 1. Imperative Scaling (Scale to 5 replicas)
kubectl scale deployment/api-deployment --replicas=5

# 2. Update Image Version (Triggers Zero-Downtime Rolling Update)
kubectl set image deployment/api-deployment api-container=myusername/api:v2.0

# 3. Monitor Rollout Progress
kubectl rollout status deployment/api-deployment

# 4. Instant Rollback to Previous Version (if bug detected!)
kubectl rollout undo deployment/api-deployment