Hello,

I need to have cookie store #1 on a.example.com

and I need to have cookie store #2 on b.example.com and on example.com

One method was to change cookie name per subdomain / domain, however 

 request.env['rack.session.options'][:key] = "custom_name"

does not seem to work with Rails 5.

Another method was to dynamically set cookie domain names with middleware

class DomainSession
  def initialize(app)
    @app = app
  end

  def call(env)
    if env["SERVER_NAME"].start_with?("system.")
      env["rack.session.options"][:domain] = ".#{env["SERVER_NAME"]}"
    else
      env["rack.session.options"][:domain] = env["SERVER_NAME"].split(".").size < 3 ?
                                                 ".#{env["SERVER_NAME"]}" :
                                                 ".#{env["SERVER_NAME"].split(".")[1..-1].join(".")}"
    end
    @app.call(env)
  end
end

 However, this does not work too, because ".example.com" includes "system" as for its "." in the beginning, I think that's how cookies work.

Could you help? Thanks.