Docker & Kubernetes for Beginners

Containerization has revolutionized how we deploy applications. This guide introduces Docker and Kubernetes from the ground up.

What is Docker?

Docker packages your application and its dependencies into a standardized unit called a container. Containers are:

• - Portable: Run anywhere Docker is installed
• Isolated: Don't interfere with other applications
• Lightweight: Share the host OS kernel

Your First Dockerfile

WORKDIR /app

COPY package*.json ./ RUN npm ci --only=production

COPY . .

EXPOSE 3000 CMD ["node", "server.js"] ```

Essential Docker Commands

# Build an image

# Run a container docker run -p 3000:3000 myapp:latest

# List running containers docker ps

# Stop a container docker stop ```

What is Kubernetes?

Kubernetes (K8s) orchestrates containers at scale. It handles:

• - Scaling: Run multiple instances of your app
• Load balancing: Distribute traffic automatically
• Self-healing: Restart failed containers
• Rolling updates: Deploy without downtime

Basic Kubernetes Concepts

Pods The smallest deployable unit. Usually contains one container.

Deployments Manage pod replicas and updates.

Services Expose pods to network traffic.

Your First Deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: myapp
        image: myapp:latest
        ports:
        - containerPort: 3000

Conclusion

Docker and Kubernetes are essential skills for modern developers. Start with Docker, understand containers, then graduate to Kubernetes for production deployments.