How do I detect the current page in a Jekyll tag plugin?

Turns out we can also do this like:

  def render(context)
    page_url = context.environments.first["page"]["url"]

Which is not obvious but it doesn't require patching the code.

context['page'] seems to return a hash with most of the properties of the current page, including url and path

so the actual page object can be retrieved with

context.registers[:site].pages.detect { |p| p.path==context['page']['path'] }