Docker & Kubernetes - A Practical Guide

Containers have revolutionized how we deploy applications. Let's dive into Docker and Kubernetes.

What is Docker?

Docker packages applications into containers - lightweight, standalone units that include everything needed to run.

FROM node:20-alpine
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
EXPOSE 3000
CMD ["npm", "start"]

Building Your First Image

docker build -t my-app:latest .
docker run -p 3000:3000 my-app:latest

Enter Kubernetes

Kubernetes orchestrates containers at scale:

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

Key Concepts

• Pods: Smallest deployable units
• Services: Network abstraction
• Deployments: Declarative updates
• ConfigMaps: Configuration management

Conclusion

Docker and Kubernetes are essential tools for modern development. Start with Docker, then graduate to Kubernetes as your needs grow.