Upgraded Rails to 6, getting Blocked host Error

Question

I needed the new function in ActiveStorage to resize_to_fill so I upgraded to Ruby 2.5.1 and Rails 6.

ruby \'2.5.1\'

gem \"rails\", github: \"rails/rails\"
         


        

Answer 1

In Rails 6 Action Pack introduced ActionDispatch::HostAuthorization and by default allows only [IPAddr.new(“0.0.0.0/0”), IPAddr.new(“::/0”), “localhost”]

You can add arrays of RegExp, Proc, IPAddr and String or a single String in the file config/application.rb like this

class Application < Rails::Application
  config.hosts << "xxxxxxx-xxxxxxx.c9users.io"
  ...
end

From "https://drivy.engineering/rails-6-unnoticed-features":

Rails 6 added a new middleware called ActionDispatch::HostAuthorization allowing you to whitelist some hosts for your application and preventing Host header attacks. You can easily configure it with a String, IPAddr, Proc and RegExp (useful when dealing with wildcard domains).