README.md

Apartment

Multitenancy for Rails 3

Apartment provides tools to help you deal with multiple databases in your Rails environment. If you need to have certain data sequestered based on account or company, but still allow some data to exist in a common database, Apartment can help.

Installation

Rails 3

Add the following to your Gemfile:

  gem 'apartment'

That's all you need to set up the Apartment libraries. If you want to switch databases on a per-user basis, look under "Usage - Switching databases per request", below.

NOTE: You must use Rails >= 3.0.10, it contains a patch that has better postgresql schema support

Usage

Creating new Databases

Before you can switch to a new apartment database, you will need to create it. Whenever you need to create a new database, you can run the following command:

 Apartment::Database.create('database_name')

Apartment will create a new database in the following format: "environment_database_name". In the case of a sqlite database, this will be created in your 'db/migrate' foler. With other databases, the database will be created as a new DB within the system.

When you create a new database, all migrations will be run against that database, so it will be up to date when create returns.

Notes on PostgreSQL

PostgreSQL works slightly differently than other databases when creating a new DB. If you are using PostgreSQL, Apartment will set up a new schema and migrate into there. This provides better performance, and allows Apartment to work on systems like Heroku, which would not allow a full new database to be created.

Switching Databases

To switch databases using Apartment, use the following command:

Apartment::Database.switch('database_name')

When switch is called, all requests coming to ActiveRecord will be routed to the database you specify (with the exception of excluded models, see below). To return to the 'root' database, call switch with no arguments.

Switching Databases per request

You can have Apartment route to the appropriate database by adding some Rack middleware. Apartment can support many different "Elevators" that can take care of this routing to your data. In house, we use the subdomain elevator, which analyzes the subdomain of the request and switches to a database schema of the same name. It can be used like so:

# application.rb
module My Application
  class Application < Rails::Application
  
    config.middleware.use 'Apartment::Elevators::Subdomain'
  end
end

Config

Excluding models

If you have some models that should always access the 'root' database, you can specify this by configuring Apartment using Apartment.configure. This will yield a config object for you. You can set excluded models like so:

Apartment.configure do |config|
  config.excluded_models = [User, Company]        # these models will not be multi-tenanted, but remain in the global (public) namespace
end

Managing Migrations

In order to migrate all of your databases (or posgresql schemas) you need to provide a list of dbs to Apartment. You can make this dynamic by providing a Proc object to be called on migrations. This object should yield an array of string representing each database name. Example:

# Dynamically get database names to migrate
Apartment.configure do |config|
  config.database_names = lambda{ Customer.select(:database_name).map(&:database_name) }
end

# Use a static list of database names for migrate
Apartment.configure do |config|
  config.database_names = ['db1', 'db2']
end

You can then migration your databases using the rake task:

rake apartment:migrate

This basically invokes Apartment::Database.migrate(#{db_name}) for each database name supplied from Apartment.database_names

Delayed::Job

In Apartment's current state, it doesn't seem to queue jobs properly using DJ. For whatever reason, DJ jobs are created in the current schema, even though the DJ is part of the ignored models. I have to look into this further, but until then use Apartment::Delayed::Job.enqueue to ensure that queues are placed in the public schema

In order to make ActiveRecord models play nice with DJ and Apartment, include Apartment::Delayed::Requirements in any model that is being serialized by DJ. Also ensure that a database attribute is set on this model before it is serialized, to ensure that when it is fetched again, it is done so in the proper Apartment db context. For example:

class SomeModel < ActiveRecord::Base
  include Apartment::Delayed::Requirements
end

class SomeDJ

  def initialize(model)
    @model = model
    @model.database = Apartment::Database.current_database
  end

  def perform
    # do some stuff
  end
end

Contributing

• Please issue pull requests to the development branch. All development happens here, master is used for releases
• Ensure that your code is accompanied with tests. No code will be merged without tests

TODO

• Cross-database associations