Koi is another 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.

This server operates in every capacity as a static file server, unless the file it is serving begins with . i.e. hidden files or the file ends a .erb extension.

Files ending with a .erb extension use the ERB markup syntax to generate responses that are assumed to be `gemtext`, under most circumstances. That said, each file is executed with it’s directory as the PWD and it injects binds the following into the ERB environment:

These object can be set to override default gemtext generation. This particular property changes the response code with the raw Gemini code for a given response e.g. 10 is input required.

This is the metadata object of the response that can be overridden to supply supplementary info for a given response. e.g. a redirect URL, a new content type header, a query description text.

This can be used to return arbitrary content and overrides what .erb evaluates to if set. You could theoretically generate and serve images from an .erb by setting this property with the correct mime type set in the metadata.

Here is a contrived example that demonstates the power of ERB templating in this context:

# Search my posts

<% if request.query == "" %>
   <% @response_status = 10 %>
   <% @response_metadata = "Enter a filter term" %>
<% end %>

<% `ls`.split("\n").select {|x| x.start_with?(@request.query) and x.end_with?(".gmi")}.each do |item| %>
    => gemini://mysite.com/posts/<%= item %>
<% end %>

Running your own server is as simple as installing one gem: `koi` and pointing it at a cert and key that you might even generate using `koi`.

# Defaults are -s nil -b 0.0.0.0 -p 1965 -e (.erb enabled)

koi -s /home/user/public_gmi

OR

koi -s /home/user/public_gmi -b 0.0.0.0 -p 1965

OR

koi -s /home/user/public_gmi -b 0.0.0.0 -p 1965 --no-erb

OR

koi -s /home/user/public_gmi -b 0.0.0.0 -p 1965 -e -k key.pem -c cert.pem

FOR CERTIFICATE GENERATION

koi -g COMMONNAME

No AI tools were used at any point during developemnt or documentation. This project was expressly 100% hand-written by a human.