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

The Blocked Host is a new feature of Rails 6. You can add this pattern to your config/environments/development.rb to have no worries of that in case of dynamic urls

config.hosts << /[a-z0-9]+\.c9users\.io/

Also for ngrok user, just replace above c9users by ngrok

Source: https://github.com/MikeRogers0/puma-ngrok-tunnel

Answer 2

This article worked for me:

1. The first option is to whitelist the hostnames in config/environments/development.rb:

   Rails.application.configure do
     config.hosts << "hostname" # Whitelist one hostname
     config.hosts << /application\.local\Z/ # Whitelist a test domain
   end
   

2. The second option is to clear the entire whitelist, which lets through requests for all hostnames:

   Rails.application.configure do
     config.hosts.clear
   end
   

Credit goes to Manfred Stienstra.

Answer 3

As I said above in my comment, here's what I did. Reposted due to down-votes.

I added Rails.application.config.hosts << "xxxxxxx-xxxxxxx.c9users.io" to config/application.rb and it fixed my test app fine. Then I did it to my real app and it also worked. The problem is, Devise threw an error as well, which apparently won't be fixed until at least Rails 6 beta. I guess I'm going back to Carrierwave for my image sizing needs until ActiveStorage is more mature.

Answer 4

If you want to disable this functionality on your development environment, you can set

config.hosts = nil in config/environments/development.rb.

Answer 5

Simple solution:

Add this line to config/environments/development.rb

config.hosts << /[a-z0-9]+\.ngrok\.io/

Restart your rails server and it will work

Answer 6

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).