Simple Jekyll plugin for creating a CDN url Liquid filter

_config.yml

#cdn
cdnurl: 'https://s3-eu-west-1.amazonaws.com/outoftime/'

cdn_url_filter.rb

module Jekyll
  module CdnUrlFilter
      
    def cdn_url(input)        
      resolvedPath = input

      # Strip the leading slash if there's any.
      if resolvedPath.start_with?('/')
        resolvedPath = resolvedPath[1..-1]
      end

      "#{@context.registers[:site].config['cdnurl']}#{resolvedPath}"
    end
  end
end

Liquid::Template.register_filter(Jekyll::CdnUrlFilter)