Kubernetes Deployments¶

Overview¶

This guide covers deployment strategies, configurations, and best practices for managing application deployments in Kubernetes.

Prerequisites¶

Basic understanding of Kubernetes concepts
Knowledge of kubectl commands
Familiarity with YAML configuration
Understanding of container lifecycle

Learning Objectives¶

Understand deployment strategies
Learn deployment configuration
Master rolling updates
Implement deployment patterns
Handle deployment rollbacks

Deployment Basics¶

Basic Deployment Structure¶

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80

Deployment Components¶

metadata: Name and labels for the deployment
spec.replicas: Number of desired pods
spec.selector: How the deployment finds pods to manage
spec.template: Pod template specification

Deployment Strategies¶

Rolling Update¶

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0

Blue-Green Deployment¶

# Blue deployment
apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-blue
spec:
  template:
    metadata:
      labels:
        app: myapp
        version: blue

---
# Green deployment
apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-green
spec:
  template:
    metadata:
      labels:
        app: myapp
        version: green

Canary Deployment¶

# Main deployment
apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-main
spec:
  replicas: 9
  template:
    metadata:
      labels:
        app: myapp
        version: stable

---
# Canary deployment
apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-canary
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: myapp
        version: canary

Configuration Management¶

Environment Variables¶

apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-deployment
spec:
  template:
    spec:
      containers:
      - name: app
        image: myapp:1.0
        env:
        - name: DATABASE_URL
          value: "postgresql://db:5432"
        - name: API_KEY
          valueFrom:
            secretKeyRef:
              name: app-secrets
              key: api-key

ConfigMaps¶

apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  app.properties: |
    environment=production
    log.level=info

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-deployment
spec:
  template:
    spec:
      containers:
      - name: app
        volumeMounts:
        - name: config-volume
          mountPath: /etc/config
      volumes:
      - name: config-volume
        configMap:
          name: app-config

Rolling Updates¶

Update Strategy¶

apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-deployment
spec:
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0
  minReadySeconds: 5

Commands for Updates¶

# Update image
kubectl set image deployment/app-deployment app=myapp:2.0

# Check rollout status
kubectl rollout status deployment/app-deployment

# Pause rollout
kubectl rollout pause deployment/app-deployment

# Resume rollout
kubectl rollout resume deployment/app-deployment

Rollback Management¶

Rollback Configuration¶

apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-deployment
spec:
  revisionHistoryLimit: 10

Rollback Commands¶

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

# Rollback to previous version
kubectl rollout undo deployment/app-deployment

# Rollback to specific revision
kubectl rollout undo deployment/app-deployment --to-revision=2

Best Practices¶

Use declarative configuration
Implement proper health checks
Set resource limits
Use meaningful labels
Configure proper update strategy
Maintain revision history
Implement proper monitoring

Common Pitfalls¶

Insufficient health checks
Poor resource management
Missing rollback strategy
Inadequate monitoring
Poor version control
Insufficient testing

Implementation Examples¶

Complete Deployment Configuration¶

apiVersion: apps/v1
kind: Deployment
metadata:
  name: web-app
  labels:
    app: web
    environment: production
spec:
  replicas: 3
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0
  selector:
    matchLabels:
      app: web
  template:
    metadata:
      labels:
        app: web
    spec:
      containers:
      - name: web-app
        image: nginx:1.14.2
        ports:
        - containerPort: 80
        resources:
          requests:
            memory: "64Mi"
            cpu: "250m"
          limits:
            memory: "128Mi"
            cpu: "500m"
        livenessProbe:
          httpGet:
            path: /health
            port: 80
          initialDelaySeconds: 3
          periodSeconds: 3
        readinessProbe:
          httpGet:
            path: /ready
            port: 80
          initialDelaySeconds: 5
          periodSeconds: 5
        env:
        - name: ENVIRONMENT
          valueFrom:
            configMapKeyRef:
              name: app-config
              key: environment
        - name: API_KEY
          valueFrom:
            secretKeyRef:
              name: app-secrets
              key: api-key
        volumeMounts:
        - name: config-volume
          mountPath: /etc/config
      volumes:
      - name: config-volume
        configMap:
          name: app-config

Resources for Further Learning¶

Practice Exercises¶

Create a basic deployment
Implement rolling updates
Configure blue-green deployment
Set up canary deployment
Manage deployment rollbacks