Container Orchestration
Docker and Kubernetes patterns for containerized applications.
Dockerfile Best Practices
Use specific version, not :latest
FROM python:3.11-slim AS builder
Set working directory
WORKDIR /app
Copy dependency files first (better caching)
COPY requirements.txt . RUN pip install --no-cache-dir -r requirements.txt
Copy application code
COPY src/ ./src/
Production stage (multi-stage build)
FROM python:3.11-slim
WORKDIR /app
Create non-root user
RUN useradd --create-home appuser USER appuser
Copy from builder
COPY --from=builder /app /app
Set environment
ENV PYTHONUNBUFFERED=1
Health check
HEALTHCHECK --interval=30s --timeout=3s \ CMD curl -f http://localhost:8000/health || exit 1
EXPOSE 8000 CMD ["python", "-m", "uvicorn", "src.main:app", "--host", "0.0.0.0"]
Dockerfile Rules DO: - Use specific base image versions - Use multi-stage builds - Run as non-root user - Order commands by change frequency - Use .dockerignore - Add health checks
DON'T: - Use :latest tag - Run as root - Copy unnecessary files - Store secrets in image - Install dev dependencies in production
Docker Compose
docker-compose.yml
version: "3.9"
services: app: build: context: . dockerfile: Dockerfile ports: - "8000:8000" environment: - DATABASE_URL=postgres://user:pass@db:5432/app depends_on: db: condition: service_healthy healthcheck: test: ["CMD", "curl", "-f", "http://localhost:8000/health"] interval: 30s timeout: 10s retries: 3
db: image: postgres:15-alpine volumes: - postgres_data:/var/lib/postgresql/data environment: POSTGRES_USER: user POSTGRES_PASSWORD: pass POSTGRES_DB: app healthcheck: test: ["CMD-SHELL", "pg_isready -U user -d app"] interval: 10s timeout: 5s retries: 5
volumes: postgres_data:
Kubernetes Basics Deployment apiVersion: apps/v1 kind: Deployment metadata: name: app labels: app: myapp spec: replicas: 3 selector: matchLabels: app: myapp template: metadata: labels: app: myapp spec: containers: - name: app image: myapp:1.0.0 ports: - containerPort: 8000 resources: requests: memory: "128Mi" cpu: "100m" limits: memory: "256Mi" cpu: "500m" livenessProbe: httpGet: path: /health port: 8000 initialDelaySeconds: 10 periodSeconds: 30 readinessProbe: httpGet: path: /ready port: 8000 initialDelaySeconds: 5 periodSeconds: 10 env: - name: DATABASE_URL valueFrom: secretKeyRef: name: app-secrets key: database-url
Service apiVersion: v1 kind: Service metadata: name: app-service spec: selector: app: myapp ports: - port: 80 targetPort: 8000 type: ClusterIP
Ingress apiVersion: networking.k8s.io/v1 kind: Ingress metadata: name: app-ingress annotations: nginx.ingress.kubernetes.io/rewrite-target: / spec: ingressClassName: nginx rules: - host: app.example.com http: paths: - path: / pathType: Prefix backend: service: name: app-service port: number: 80
kubectl Quick Reference
Command Description
kubectl get pods List pods
kubectl logs