Embed gists in markdown files of a jekyll application by creating a custom Liquid tag

jekyll_gist_tag.rb

require 'cgi'
require 'digest/md5'
require 'net/https'
require 'uri'

module Jekyll
  class GistTag < Liquid::Tag
    def initialize(tag_name, text, token)
      super
      @text           = text
      @cache_disabled = false
      @cache_folder   = File.expand_path "../_gist_cache", File.dirname(__FILE__)
      FileUtils.mkdir_p @cache_folder
    end

    def render(context)
      @text.strip!
      if @text.include? " "
        gist, *rest = @text.split(/ /)
        file = rest[0]
      else
        gist = @text
      end
        script_url = script_url_for gist, file
        code       = get_cached_gist(gist, file) || get_gist_from_web(gist, file)
        html_output_for script_url, code
    end

    def html_output_for(script_url, code)
      code = CGI.escapeHTML code
      "<script src='#{script_url}'></script><div><noscript><pre><code>#{code}</code></pre></noscript></div>"
    end

    def script_url_for(gist_id, filename)
      "https://gist.github.com/#{gist_id}.js?file=#{filename}"
    end

    def get_gist_url_for(gist, file)
      "https://raw.github.com/gist/#{gist}/#{file}"
    end

    def cache(gist, file, data)
      cache_file = get_cache_file_for gist, file
      File.open(cache_file, "w") do |io|
        io.write data
      end
    end

    def get_cached_gist(gist, file)
      return nil if @cache_disabled
      cache_file = get_cache_file_for gist, file
      File.read cache_file if File.exist? cache_file
    end

    def get_cache_file_for(gist, file)
      bad_chars = /[^a-zA-Z0-9\-_.]/
      gist      = gist.gsub bad_chars, ''
      unless file.nil?
        file      = file.gsub bad_chars, ''
      end
      md5       = Digest::MD5.hexdigest "#{gist}-#{file}"
      File.join @cache_folder, "#{gist}-#{file}-#{md5}.cache"
    end

    def get_gist_from_web(gist, file)
      gist_url          = get_gist_url_for gist, file
      raw_uri           = URI.parse gist_url
      https             = Net::HTTP.new raw_uri.host, raw_uri.port
      https.use_ssl     = true
      https.verify_mode = OpenSSL::SSL::VERIFY_NONE
      request           = Net::HTTP::Get.new raw_uri.request_uri
      data              = https.request request
      data              = data.body
      cache gist, file, data unless @cache_disabled
      data
    end
  end

  class GistTagNoCache < GistTag
    def initialize(tag_name, text, token)
      super
      @cache_disabled = true
    end
  end
end

Liquid::Template.register_tag('gist', Jekyll::GistTag)
Liquid::Template.register_tag('gistnocache', Jekyll::GistTagNoCache)

This is a fork of imathis/gist_tag.rb which is not working since gists ID contains none-digit characters.

Getting started :

• Create a _plugins directory in your jekyll application.
• Add a file named gist.rb in the _plugins folder.
• Paste the content of the gist_tag.rb of this gist.

Usage:
{% gist {gistID} {filename} %}

The filename parameter is optional.