Presentation from RedDotRubyConf 2011 in Singapore. It explains multi-tenancy and why it is increasingly required for Rails development. Four of the many approaches are covered in some detail (including what resources we have available for re-use) and I end with a naive question (& call to action?) .. "Isn't it about time there was a 'Rails Way'?"

4. Three Thoughts for Today

5. A GENERAL MODEL

7. Tenancy Models

8. Tenancy Models Social networks, LBS, Web 2.0 MSP/ASP, PaaS, IaaS Business, Enterprise 2.0, SaaS The same idea can manifest itself across the continuum – depending how you approach it

9. Tenancy Models Social networks, LBS, Web 2.0 MSP/ASP, PaaS, IaaS Business, Enterprise 2.0, SaaS Hardware/infrastructure challenge Application architecture challenge Explicit Rails support.. ..but our usage increasingly extends here

10. Tenancy Considerations

11. Key Concern: Data Partitioning

12. RE-USE / RE-INVENT

22. gem install multitenant class User < ActiveRecord::Base belongs_to :account belongs_to_tenant :account belongs_to :project end = simple_form_for [user] do |f| = f.error_messages = f.input :name = f.association :project user = User.find(1) => #<User id: 1, name: &quot;a1-u1&quot;, account_id: 1 ..> Account.find(2).projects.first.id => 3 # set the current tenant Multitenant.current_tenant = user.account Project.where(:id => 3).present? => false # but we can still assign an inaccessible project: user.update_attributes(:project_id => 3).valid? => true # we can’t access the association user.project => nil # but the invalid key is persisted user.project_id => 3 Since all tenant-related models are scoped, our app will display valid options to the user But what if someone sneaks in with some form-injection?

25. Schema Partitioning User Queries Account Customer Project -- default search path: ‘$user’,PUBLIC PUBLIC

26. Schema Partitioning User Queries Account Customer Project PUBLIC User Account Customer Project TENANT1 SET search_path TO TENANT1, ‘$user’, PUBLIC;

27. Schema Partitioning User Queries Account Customer Project PUBLIC Customer Project TENANT1 SET search_path TO TENANT1, ‘$user’, PUBLIC;

31. LESSONS LEARNT AND TTD

32. Think about the End-user Experience My SaaS Site Tenant 1 Tenant 2 Tenant 3 Users Users Users

36. TAKEAWAYS