koi-server

https://github.com/JustinWoodring/Koi

Koi is a ruby-based Gemini server that supports .erb templating, and static files, and handles TLS certs for you. Koi is designed to make hosting Gemini CGI pages a joyful and tranquil experience, uniting the conceptual beauty of a simple web with developer happiness. By using a combination of Ruby powered ERB templating and traditional static file serving we distill a solution offering the best of both worlds.