📦 Docker Custom Images + Node Server Dockerization Cheatsheet 🚀
Learn to build, optimize, and run custom Docker images for Node.js applications like a pro.
📁 1. Folder Structure for a Dockerized Node App
my-app/ ├── Dockerfile ├── .dockerignore ├── package.json ├── package-lock.json ├── index.js 🛠️ 2. Create a Custom Docker Image for Node.js App
✅ Sample Optimized Dockerfile
# 👷 Stage 1: Build FROM node:20-alpine AS builder # Set working directory WORKDIR /app # Install dependencies COPY package*.json ./ RUN npm ci # Copy source code COPY . . # 🧼 Prune dev dependencies RUN npm prune --production # 🚀 Stage 2: Run FROM node:20-alpine WORKDIR /app # Copy from builder stage COPY --from=builder /app . # Set environment and expose port ENV NODE_ENV=production ENV PORT=8000 EXPOSE 8000 # Run the app CMD ["npm", "start"] 🚫 3. .dockerignore File (Very Important!)
node_modules .dockerignore Dockerfile npm-debug.log .git .env Prevents unnecessary files from being copied into your image, reducing build time and size.
⚙️ 4. Build & Run Docker Image for Node App
🧱 Build the Image
# 🧪 Build with a custom tag docker build -t my-node-app . 🚀 Run the Container
# 🧪 Run interactively docker run -p 8000:8000 my-node-app # 🧪 Run in background docker run -d -p 8000:8000 my-node-app 📂 Run with Mount (Dev Mode - Hot Reload)
docker run -v ${PWD}:/app -p 8000:8000 my-node-app Mounts your current directory inside the container, ideal for development.
🔍 5. Inspect, Debug, and Clean Containers
✅ List Containers & Images
docker ps # Running containers docker ps -a # All containers docker images # Local images 🛑 Stop & Remove
docker stop <id> # Stop container docker rm <id> # Remove container docker rmi my-node-app # Remove image 🪛 Exec Into a Container
docker exec -it <id> /bin/sh # Alpine or BusyBox docker exec -it <id> /bin/bash # Ubuntu-based 📜 Logs & Details
docker logs <id> # Show logs docker inspect <id> # Low-level config info docker history my-node-app # See image layers 🧼 6. Prune & Clean Docker Environment
docker container prune # Remove stopped containers docker image prune # Remove dangling images docker volume prune # Clean volumes docker system prune -a # Remove all unused data 🛡️ 7. Best Practices for Custom Docker Images
| Practice | Benefit |
|---|---|
Use alpine base | Reduces image size drastically 📉 |
| Multi-stage builds | Keep final image clean & minimal 🧼 |
Set .dockerignore | Avoid bloat, faster builds ⚡ |
| Cache dependencies | Speeds up builds 🎯 |
| Pin base image versions | Prevents future breaking changes 🔒 |
| Avoid root user | Increases container security 🔐 |
Clean caches in RUN steps | Reduces leftover junk 🗑️ |
🚀 8. Example Node.js Server (index.js)
// index.js const express = require('express'); const app = express(); const PORT = process.env.PORT || 8000; app.get('/', (req, res) => { res.send('Hello from Dockerized Node Server 🚀'); }); app.listen(PORT, () => { console.log(`Server running on http://localhost:${PORT}`); }); 🔍 9. Image Size Analyzer Tools
docker history my-node-app # View layers and size docker image inspect my-node-app # Use Dive CLI tool dive my-node-app # Use DockerSlim to shrink it docker-slim build my-node-app 🧪 10. Docker Compose (Bonus)
# docker-compose.yml version: '3.8' services: web: build: . ports: - "8000:8000" volumes: - .:/app environment: - NODE_ENV=production # Run with: docker-compose up --build ✅ Summary of Key Docker Commands for Node Server
| Task | Command |
|---|---|
| 🧱 Build Image | docker build -t my-node-app . |
| 🚀 Run Container | docker run -p 8000:8000 my-node-app |
| 🔍 View Running | docker ps |
| 🛑 Stop Container | docker stop <id> |
| 🗑️ Prune Containers | docker container prune |
| 🧼 Clean All | docker system prune -a |
🎁 Bonus Tip
💡 To auto-rebuild and restart on file changes during dev:
npm install -D nodemon Update package.json:
"scripts": { "start": "node index.js", "dev": "nodemon index.js" } Then in Dockerfile:
RUN npm install --only=production # OR use dev mode in compose 
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