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Imran
Imran

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🚀 Master Docker: A DevOps-Grade Tutorial for Developers and Engineers 🐳

#webdev #devops #docker #development


📌 Why Docker?

Docker eliminates "it works on my machine" problems by containerizing apps along with their environments. It’s the backbone of modern DevOps, enabling reproducible builds, fast deployments, and scalable infrastructure.

Whether you're building microservices, APIs, frontends, or full-stack SaaS apps—Docker is essential.

🔧 Prerequisites:
✅ Basic CLI knowledge
✅ A project or app to test Docker with (Node.js used here, but language doesn't matter)

🛠️ 1. Install Docker

🖥️ macOS / Windows
➡️ Install Docker Desktop: https://www.docker.com/products/docker-desktop

sudo apt update sudo apt install docker.io -y sudo systemctl start docker sudo systemctl enable docker
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Verify
docker --version

🐳 2. Understand Docker’s Core Concepts

Concept Description
Image A blueprint of your app (like a class)
Container A running instance of an image
Dockerfile Instructions to build your image
Volume Persistent storage for containers
Network Allows containers to communicate
Registry Stores images (like Docker Hub or GitHub Container Registry)

🚀 3. Running Your First Container

docker run hello-world
Explanation:

  • Pulls the hello-world image
  • Runs it inside a new container
  • Shows a success message

🧱 4. Create and Use a Dockerfile

Step-by-step: Let's Dockerize a Node.js app.
Project:

mkdir myapp && cd myapp npm init -y npm i express echo "require('express')().listen(3000)" > index.js
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DockerFile :

# Base image FROM node:18 # Set working directory WORKDIR /app # Copy files COPY package*.json ./ RUN npm install COPY . . # Expose and run EXPOSE 3000 CMD ["node", "index.js"]
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Build and Run:

docker build -t myapp . docker run -p 3000:3000 myapp
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📦 5. Use Volumes (Dev Mode)

So changes reflect without rebuilds:

docker run -p 3000:3000 -v $(pwd):/app myapp
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🔁 6. Docker Compose – Multi-Container Apps

Example: Node.js app + MongoDB

<pre> version: '3.9' services: app: build: . ports: - "3000:3000" volumes: - .:/app environment: - NODE_ENV=development depends_on: - mongo mongo: image: mongo volumes: - mongodata:/data/db ports: - "27017:27017" volumes: mongodata: </pre>
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*** Run: ***

docker-compose up --build
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💡7. Multi-Stage Docker Builds

Reduce image size and isolate build from production:

# Stage 1: Build FROM node:18 AS builder WORKDIR /app COPY . . RUN npm install && npm run build # Stage 2: Runtime FROM node:18-slim WORKDIR /app COPY --from=builder /app/dist . CMD ["node", "server.js"]
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🧰 8. Helpful Docker Commands 

docker ps -a # List all containers docker images # List images docker logs <container> # Logs docker exec -it <container> bash # Enter container docker stop <id> # Stop container docker rm <id> # Remove container docker rmi <image> # Remove image
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🔐 9. Docker Security Best Practices

✅ Use minimal base images (alpine, node:slim)
✅ Use .dockerignore like .gitignore
✅ Run as non-root if possible
✅ Use image scanning tools:

docker scout quickview # or trivy image myapp
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🔄 10. Real DevOps CI/CD with Docker

GitHub Actions Example:

<pre> name: Docker CI on: push: branches: [ main ] jobs: build: runs-on: ubuntu-latest steps: - uses: actions/checkout@v3 - name: Build Docker image run: docker build -t myorg/myapp:${{ github.sha }} . - name: Push to Docker Hub run: | echo "${{ secrets.DOCKER_PASS }}" | docker login -u ${{ secrets.DOCKER_USER }} --password-stdin docker push myorg/myapp:${{ github.sha }} </pre>
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🧪 11. Advanced Real-World Scenarios

📌 Run PostgreSQL + Adminer for Dev:

services: db: image: postgres environment: POSTGRES_PASSWORD: pass adminer: image: adminer ports: - "8080:8080"
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🧩 Host React or Next.js with Nginx:

FROM node:18 AS builder WORKDIR /app COPY . . RUN npm install && npm run build FROM nginx:alpine COPY --from=builder /app/build /usr/share/nginx/html
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🧼 12. Clean Up Resources 

docker system prune -a docker volume prune docker image prune
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🧠 Conclusion: Docker is DevOps

Once you’ve mastered Docker:

  • Build fast, reproducible workflows
  • Deploy secure, production-ready images
  • Use in CI/CD pipelines
  • Plug into Kubernetes or serverless platforms

💬 Want More?

Let me know in the comments if you want a follow-up:

  • 🧭 Kubernetes for Docker users
  • 🛠️ Docker + Ansible + Terraform workflow
  • 🧠 Docker debugging & profiling tools

🧑‍💻 Connect With Me

📺 YouTube: Codewithimran
🐙 GitHub: Codewithimran
💡 LinkedIn: Codewithimran

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