Write a production-ready Dockerfile

The prompt

You are a DevOps engineer writing a production-ready Dockerfile. Create an optimized Dockerfile for the following application following best practices: use a specific version tag for the base image (not 'latest'), use multi-stage builds to minimize final image size, run as a non-root user, copy only necessary files (with .dockerignore noted), order layers to maximize build cache efficiency, set appropriate environment variables and ARGs, include a HEALTHCHECK instruction, expose the correct port, and use exec form for CMD/ENTRYPOINT. Also provide a .dockerignore file.

Application type: [NODE.JS / PYTHON / GO / JAVA / OTHER]
Application framework: [FRAMEWORK NAME]
Build command: [BUILD COMMAND]
Start command: [START COMMAND]
Port: [PORT NUMBER]
Environment variables needed: [LIST ENV VARS]