The Complete Guide to Docker: Everything You Need to Know About Container Technology 🐳🌐

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🔍 What is Docker?

It’s a container-based virtualization technology, an open-source platform that allows you to package your applications along with their dependencies and run them anywhere.
> 💡 Traditional virtualization (VM) vs Docker > – VM: hardware virtualization → heavy (in GB) > – Docker: OS kernel sharing → lightweight and fast (in MB) > (Image: VM vs Docker structure comparison).

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✨ Docker core concepts

1️⃣ Images (e.g., `ubuntu’)

• Executable read-only templates (e.g. ubuntu:22.04, nginx:latest)
• Organized in a Layer structure for efficient management

2️⃣ Containers (e.g., buntu:04, ginx:latest)

• The isolated process that ran the image

  docker run -d -p 8080:80 --name my_nginx nginx # Run NGINX container

3️⃣ Dockerfile Dockerfile for building an image

• Blueprint for building the image

  FROM python:3.9
  WORKDIR /app
  COPY requirements.txt .
  RUN pip install -r requirements.txt
  COPY . .
  CMD ["python", "app.py"]

4️⃣ Docker Hub **Docker Hub

• Public image repository (e.g., hub.docker.com) (Image: Docker Hub interface).

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⚙️ Docker Architecture

• Docker daemon (Dockerd): background service
• Docker Client: Handles user commands (docker run, etc.)
• Registry: image repository (Docker Hub, Private Registry)

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🛠️ From installation to practice

1️⃣ How to install (Ubuntu example)

sudo apt-get update
sudo apt-get install docker-ce docker-ce-cli containerd.io

2️⃣ Basic Command Checklist

3️⃣ Lab: Containerizing a Node.js App

Dockerfile

FROM node:18
WORKDIR /usr/src/app
COPY package*.json ./
RUN npm install
COPY . .
EXPOSE 3000
CMD ["node", "server.js"]

**Build and Run

docker build -t my-node-app . # Build the image
docker run -p 3000:3000 my-node-app # Run the container

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🚀 Docker Compose

**Manage multi-container applications

# docker-compose.yml
version: '3.8'
services:
  web:
    image: nginx:alpine
    ports:
      - "80:80"
  db:
    image: postgres:14
    environment:
      POSTGRES_PASSWORD: mysecretpass

docker-compose up -d # Start the service

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📌 Precautions when using Docker

1. Containers are stateless.
   • Must use Volume for data persistence

     docker run -v /host/path:/container/path mysql

2. Set up security
   • Minimize root privileges → Use USER directive
3. optimize the image
   • Reduce size with multi-stage builds

     FROM golang:1.20 AS builder
     # build stages...
     FROM alpine:latest
     COPY --from=builder /app/binary . # Final image only contains build results

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💡 Docker’s transformative value.

• Dev/Ops environment consistency** → Solve the “it works on my local…” problem ✨
• CI/CD pipeline core (Jenkins, GitLab CI integration)
• Cloud-native ecosystem foundation (Kubernetes, AWS ECS, etc.)

> 🎯 “Docker is an essential tool for modern software development, > and has completely changed the paradigm of application deployment!” **.

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🔮 Docker Learning Resources

1. the official documentation – the most accurate source of information 💯
2. Play with Docker – online hands-on lab environment
3. Docker Community – GitHub, Stack Overflow

> **🚀 Get started with Docker today! > bash > docker run hello-world # Run your first container! >

(GIF: Flow of running a Docker container).