Rails - Separate Database per Subdomain

Question

I am about to begin writing a Rails application that will allow clients to have a separate subdomain for their access to our application. Thinking from a data security stand

Answer 1

Off the top of my head you could run a new server instance for each subdomain using different environment.

But that won't scale very well.

However the first few google hits for multiple rails databases turn up some new suggestions. Putting together the information in those links provides this wholly untested solution for a single server instance.

You'll need to add a database entry for each subdomain in your databases.yml. Then add a before_filter to your application controller

Update! Example reloads the database configurations dynamically. Unfortunately there's no good way to make the update rails wide without messing with your server's internals. So the database configuration will have to be reloaded on every request.

This example assumes database entries in databases.yml are named after subdomains.

config/database.yml

login: &login
  adapter: mysql
  username: rails
  password: IamAStrongPassword!
  host:  localhost

production:
  <<: *login
  database: mysite_www

subdomain1:
  <<: *login
  database: mysite_subdomain1

subdomain2:
  <<: *login
  database: mysite_subdomain2
...

app/controllers/application_controller.rb require 'erb' before_filter :switch_db_connection

def switch_db_connection
  subdomain = request.subdomains.first
  ActiveRecord::Base.configurations = YAML::load(ERB.new(IO.read(Rails.configuration.database_configuration_file)).result)
  ActiveRecord::Base.establish_connection("mysite_#{subdomain}") 
end

As I said it's completely untested. But I don't foresee any major problems. If it doesn't work hopefully it puts you on the right track.