has_remote_file_modified: Ruby method to examine the http header and see if a file is newer on the remote system

has_remote_file_modified.rb

class Chef
  class Recipe
    def has_remote_file_modified(uri, filepath)
      require 'net/http'

      http = Net::HTTP.new(uri.host, uri.port)
      req = Net::HTTP::Head.new(uri.path)
      if uri.user
        req.basic_auth uri.user, uri.password
      end
      resp = http.request(req).to_hash
      server_date = Time.httpdate(resp['last-modified'].first)
      file_date = File.mtime(filepath)
      file_date < server_date
    end
  end
end