Docker Multi-Stage Builds & Production Kubernetes Deployment Guide

Deploying microservices to production requires minimal container images, zero-downtime rolling updates, and self-healing cluster orchestration. Learn how to write multi-stage Dockerfiles that reduce image sizes from 850MB to 45MB, and configure Kubernetes Horizontal Pod Autoscalers (HPA).

1. Production Multi-Stage Dockerfile for Spring Boot / Java 21

# Stage 1: Build & Package Application
FROM eclipse-temurin:21-jdk-alpine AS builder
WORKDIR /app
COPY .mvn/ .mvn
COPY mvnw pom.xml ./
RUN ./mvnw dependency:go-offline
COPY src ./src
RUN ./mvnw package -DskipTests

# Stage 2: Minimal Distroless Production Runtime Container
FROM eclipse-temurin:21-jre-alpine AS runner
WORKDIR /app
RUN addgroup -S appgroup && adduser -S appuser -G appgroup
USER appuser
COPY --from=builder /app/target/*.jar app.jar

EXPOSE 8080
ENTRYPOINT ["java", "-XX:+UseG1GC", "-XX:MaxRAMPercentage=75.0", "-jar", "app.jar"]

2. Kubernetes Deployment Spec with Health Probes & Resource Limits

apiVersion: apps/v1
kind: Deployment
metadata:
  name: backend-api
  labels:
    app: backend-api
spec:
  replicas: 3
  selector:
    matchLabels:
      app: backend-api
  template:
    metadata:
      labels:
        app: backend-api
    spec:
      containers:
      - name: api
        image: registry.company.com/backend-api:v2.4.0
        ports:
        - containerPort: 8080
        resources:
          requests:
            memory: "256Mi"
            cpu: "250m"
          limits:
            memory: "512Mi"
            cpu: "500m"
        livenessProbe:
          httpGet:
            path: /actuator/health/liveness
            port: 8080
          initialDelaySeconds: 20
          periodSeconds: 10
        readinessProbe:
          httpGet:
            path: /actuator/health/readiness
            port: 8080
          initialDelaySeconds: 15
          periodSeconds: 5

3. Kubernetes Horizontal Pod Autoscaler (HPA v2) Manifest

apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: backend-api-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: backend-api
  minReplicas: 3
  maxReplicas: 20
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 75
  - type: Resource
    resource:
      name: memory
      target:
        type: Utilization
        averageUtilization: 80

4. Helm Chart Chart.yaml & Values.yaml Strategy

# Chart.yaml
apiVersion: v2
name: backend-service
version: 1.0.0
appVersion: "2.4.0"
description: Production Helm chart for microservice deployments

# values.yaml
replicaCount: 3
image:
  repository: registry.company.com/backend-api
  pullPolicy: IfNotPresent
  tag: "v2.4.0"

service:
  type: ClusterIP
  port: 8080

ingress:
  enabled: true
  className: nginx
  annotations:
    cert-manager.io/cluster-issuer: "letsencrypt-prod"
  hosts:
    - host: api.company.com
      paths:
        - path: /
          pathType: Prefix

5. Related DevOps Resources

• 📖 Docker CLI Cheatsheet & Command Reference
• 📖 DevOps & Cloud Infrastructure Learning Roadmap
• 📖 Python 3.12 & FastAPI Microservices Guide

6. Frequently Asked Questions (FAQ)