Docker Best Practices for Node.js Applications

Docker has become essential for deploying Node.js applications. Here's how to do it right.

The Basics

A simple Dockerfile works, but we can do much better with some optimizations.

Multi-Stage Builds

Separate build and runtime stages for smaller images. Your final image only contains what's needed to run, not build.

Layer Caching

Docker caches layers. Order your instructions from least to most frequently changing:

1. Base image (rarely changes)
2. System dependencies (rarely changes)
3. package.json (changes occasionally)
4. npm install (triggered by package.json changes)
5. Source code (changes frequently)

Security Best Practices

• Don't run as root - Create a non-root user
• Use specific versions - Don't use node:latest
• Scan for vulnerabilities - Use docker scan or Snyk

Health Checks

Add health checks so orchestrators know if your app is healthy.

Environment Variables

Don't bake secrets into your image. Pass them at runtime.

Conclusion

Good Docker practices lead to faster builds, smaller images, more secure deployments, and easier debugging. Start simple, then optimize as needed.