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

I found a different solution that works a little easier, but makes the assumption you have a database for each Subdomain:

application_controller.rb

before_filter :subdomain_change_database

def subdomain_change_database
  if request.subdomain.present? && request.subdomain != "www"
    # 'SOME_PREFIX_' + is optional, but would make DBs easier to delineate
    ActiveRecord::Base.establish_connection(website_connection('SOME_PREFIX_' + request.subdomain ))
  end
end

# Return regular connection hash but with database name changed
# The database name is a attribute (column in the database)
def website_connection(subdomain)
  default_connection.dup.update(:database => subdomain)
end

# Regular database.yml configuration hash
def default_connection
  @default_config ||= ActiveRecord::Base.connection.instance_variable_get("@config").dup
end

This will switch to a database like mydb_subdomain. This is a complete replacement database option, but it makes it super easy to roll out multiple versions.

Answer 2

Turns out I just asked a really similar question but quite a bit further along in development - I've included three ideas for how to go about securely using a single database in there.

Answer 3

Here is some code I use for this very problem:

application_controller.rb

before_filter :set_database

helper_method :current_website

# I use the entire domain, just change to find_by_subdomain and pass only the subdomain
def current_website    
  @website ||= Website.find_by_domain(request.host)
end

def set_database
  current_website.use_database
end

# Bonus - add view_path
def set_paths
  self.prepend_view_path current_website.view_path unless current_website.view_path.blank?
end

Website.rb

def use_database
  ActiveRecord::Base.establish_connection(website_connection)
end

# Revert back to the shared database
def revert_database
  ActiveRecord::Base.establish_connection(default_connection)
end

private

# Regular database.yml configuration hash
def default_connection
  @default_config ||= ActiveRecord::Base.connection.instance_variable_get("@config").dup
end

# Return regular connection hash but with database name changed
# The database name is a attribute (column in the database)
def website_connection
  default_connection.dup.update(:database => database_name)
end

Hope this helps!

Answer 4

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.