Docker for Node.js Developers: Containers from Zero to Production

Why Docker?

Docker packages your application and all its dependencies into a portable container. The classic "it works on my machine" problem disappears because dev, staging, and production all run the identical container image.

Writing a Dockerfile

Start from an official node image, set the working directory, copy package files first, run npm ci, then copy the rest of the source. Build the app and expose the port. Use a multi-stage build to keep the final image small — the builder stage can install dev dependencies without polluting production.

Docker Compose for Local Development

Use docker-compose.yml to define your app and its dependencies (MongoDB, Redis, etc.) as services. A single docker compose up starts everything. Volumes mount local code so changes reflect immediately without rebuilding the image.

Production Best Practices

Run containers as a non-root user. Set NODE_ENV=production to disable development error messages. Use .dockerignore to exclude node_modules and .git. Pin dependency versions in package.json and use npm ci instead of npm install for reproducible builds.