Multi-tenancy in Rails applications

 https://softwarebrothers.co/blog/multi-tenancy-in-ruby-on-rails-many-tenants-in-one-application/

Building a Multi-Tenant Ruby-on-Rails app

 https://blog.appsignal.com/2020/12/02/building-a-multi-tenant-ruby-on-rails-app-with-subdomains.html

Association Defaults in Ecto (Designing secure and scalable multi-tenant applications in Elixir)

https://twitter.com/slab/status/1375128887538057217?s=21 

https://slab.com/blog/association-defaults-in-ecto/