docker-gen is a Go CLI tool that generates configuration files from Docker container metadata using Go templates. It connects to the Docker daemon, lists containers based on configurable filters (exposed ports, labels, etc.), and renders templates with container data (IPs, ports, environment variables, labels, networks). The generated output can be written to files or stdout, and docker-gen can notify services by running commands or sending signals to containers when the output changes. It supports watching Docker events for automatic regeneration with configurable debouncing. The architecture is a single binary with well-separated internal packages: config parsing, Docker client abstraction, container context extraction, template engine with custom functions (filtering, grouping, sorting, nginx-specific quoting/HSTS validation), and a generator that orchestrates event listening, signal handling, and file generation. The codebase is mature, extensively tested, and demonstrates high craftsmanship in its generic template helper functions (deepGet, where, groupBy, sortBy) which are reusable beyond this project. It is primarily used as part of the nginx-proxy ecosystem to auto-generate reverse proxy configurations, but can be adapted for any file generation from Docker metadata.