🐳

Dockerfile Linter

Lint Dockerfile for best practices and common issues.

Input
Lint Results

📖 What is Dockerfile Linter?

Dockerfile Generator creates production-ready Dockerfiles based on your application type. Select your language/framework (Node.js, Python, Go, Java), configure settings, and get a Dockerfile following Docker best practices — multi-stage builds, non-root users, layer caching and minimal base images. Use it to containerize applications quickly without memorizing Dockerfile syntax. Everything runs in your browser.

💡 Example

Input
Language: Node.js Port: 3000 Package Manager: npm
Output
FROM node:20-alpine WORKDIR /app COPY package*.json ./ RUN npm ci --production COPY . . EXPOSE 3000 CMD ["node", "server.js"]

🛠️ Common Use Cases

  • Creating Dockerfiles for new projects without memorizing syntax
  • Following Docker best practices (multi-stage, non-root, layer caching)
  • Generating optimized Dockerfiles for CI/CD pipelines
  • Learning Dockerfile structure and common patterns
  • Quickly containerizing applications for deployment

📝 Docker Best Practices

  • Use alpine or slim base images for smaller containers
  • Copy package files first, then run install — this caches dependencies
  • Use .dockerignore to exclude node_modules, .git, etc.
  • Run as non-root user for security
  • Use multi-stage builds to separate build and runtime

⚠️ Common Mistakes

  • No .dockerignore — without it, COPY includes everything (node_modules, .git), creating bloated images
  • Running as root — containers should use a non-root user for security
  • Not caching dependencies — COPY everything before npm install means reinstalling on every code change

❓ Frequently Asked Questions

Should I use alpine or slim base images?
Alpine produces smaller images (~5MB vs ~100MB for Debian). Use alpine unless your app needs glibc-specific libraries, in which case use slim.
What is a multi-stage build?
Multi-stage builds use separate stages for building (with dev dependencies) and running (only production files). The final image is much smaller.
How do I reduce Docker image size?
Use alpine base images, multi-stage builds, .dockerignore, and combine RUN commands to reduce layers.
Is my data private?
Yes — all processing runs entirely in your browser. Your data is never sent to any server.
Is this tool free?
Completely free — no login, no usage limits, works offline once loaded.
Yes — completely free, no login required, no usage limits.
Is my data private?
Yes — all processing runs in your browser. Your data is never sent to any server.
Does it work offline?
Yes — once the page is loaded, the tool works without an internet connection.
🔒
Your data stays private. All processing happens entirely in your browser using JavaScript. Nothing is ever sent to our servers. You can even use this tool offline after the page loads.