Registers :build permalink placeholder that is replaced with the site build time (useful for cache-busting files)

buildtime.rb

# https://articles.inqk.net/2020/02/10/jekyll-permalinks.html
# place in `_plugins` directory
module Jekyll
	module Drops
		class UrlDrop < Drop
			def build
				@context.registers[:site].time.strftime("%s")
			end
		end
	end
end

Hmmm, have had a look around the Jekyll codebase and I think there should be a .site method accessible on @obj that will get you the site. I don't know if that object has a .time method on it but maybe give that a try and see how it goes.

To be clear, rather than:

@context.registers[:site].time.strftime("%s")

you'd have:

@obj.site.time.strftime("%s")