Deployment

A Deployment in Kubernetes manages the lifecycle of a set of Pods, ensuring that the desired number of replicas are running and updated in a controlled manner. It supports rolling updates, rollbacks, and scaling, providing high availability and easy management of applications.

Deployments Manifest File

deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-tier
  labels:
    app: microservices
    tier: app
spec:
  replicas: 5
  selector:
    matchLabels:
      tier: app
  template:
    metadata:
      labels:
        app: microservices
        tier: app
    spec:
      containers:
      - name: server
        image: lrakai/microservices:server-v1
        ports:
         - containerPort: 8080
        resources:
          requests:
            cpu: 20m
        env:
          - name: REDIS_URL
            value: redis://$(DATA_TIER_SERVICE_HOST):$(DATA_TIER_SERVICE_PORT_REDIS)
          - name: PASSWORD
            valueFrom:
              secretKeyRef:
                name: app-tier-secret
                key: password
        

After make the manifest file, we apply the manifest to create deployment

kubectl apply -f deployment.yaml

Then check the deployment

# Get Deployment
kubectl get deployment -n [NAMESPACE]

in deployment we can do Rollout and Rollback

# Rollout Restart (Triggers a rolling restart)
kubectl rollout restart deployment [DEPLOYMENT_NAME] -n [NAMESPACE]

# Rollback to the previous revision
kubectl rollout undo deployment [DEPLOYMENT_NAME] -n [NAMESPACE]

# Rollback to a specific revision (optional)
kubectl rollout undo deployment [DEPLOYMENT_NAME] --to-revision=[REVISION] -n [NAMESPACE]