How to use subdomain with ActiveAdmin on rails

Question

I'm trying to access the ActiveAdmin with subdomain "admin.localhost.local:3030" instead of namespace "localhost:3030/admin". I looked it up and I found that I should change the default namespace in "config/initializers/active_admin.rb" to false

config.default_namespace = false

and I surrounded the routes in "routes.rb" with subdomain constraints

constraints :subdomain => "admin" do
    ActiveAdmin.routes(self)
end

also, I changed "/etc/hosts" localhost line to be able to test on my machine

127.0.0.1    admin.localhost.local

but for some reason, it still doesn't work. I'm trying to access the subdomain by writing admin.localhost.local:3030 and this is what I get from the browser: "The admin.localhost.local page isn't working. admin.localhost.local redirected you too many times."

Answer 1

The infinite redirect could be because of the Devise configuration. Try the suggestion here:

constraints :host => 'admin.spikeatschool.local' do
  ActiveAdmin.routes(self)
  devise_for :admin_users, ActiveAdmin::Devise.config.merge(:path => '')
end

https://github.com/activeadmin/activeadmin/issues/691#issuecomment-8583834