Add multiple subdomains to your rails 7 app.

Subdomains are a great way to organize different parts of your app. You might have an api subdomain, news subdomain, etc.

routes.rb

constraints subdomain: 'my-subdomain' do
  # add routes
end

development.rb

Add new hosts to your development.rb configuration.

config.hosts << "my-subdomain.my-domain.local"

Development Environment

Add development subdomain(s) to your /etc/hosts file so it routes to your development server

127.0.0.1 my-subdomain.my-domain.local

Don't forget to add port 3000! You'll go this url in your browser. my-subdomain.my-domain.local:3000

Heroku

DNS Configuration

Add a CNAME record for each subdomain in your DNS configuration.

Use the domain name and DNS Target from Heroku.

That's it! You should be good to go.