Activerecord Tenanted

activerecord-tenanted (SQLite per tenant)

One SQLite file per tenant via the Basecamp activerecord-tenanted gem. Identity, sessions, and the tenant row live in a global database. Product data lives in storage/tenants/{env}/{tenant_key}/main.sqlite3.

This is the Herald / Cortex / Innkeeper model. It is not:

• Nebula acts_as_tenant — one database, workspace_id on every row
• Fizzy path tenancy — one database, Current.account + SCRIPT_NAME URL prefix

If the app already uses acts_as_tenant or Fizzy-style account slugs in a shared schema, do not introduce this gem.

Philosophy

1. Two base classes, two databases. GlobalRecord never sees tenant data. ApplicationRecord never sees identities.
2. No tenanted query without a tenant. User.find outside with_tenant / Current.tenant= is a bug, even in jobs and rake tasks.
3. The URL (or Current) chooses the shard. The gem's default subdomain resolver is wrong for path-based apps — disable it.
4. Jobs re-enter the tenant. Active Job does not magically carry the shard. Pass a global id (account/tenant/project) and wrap perform in with_tenant.

What Goes Where

Herald keeps Project global (so slugs/API keys exist before a shard is selected) and stores releases/subscribers in the account tenant. Cortex/Innkeeper put almost all product tables in the tenant DB. Both are fine — pick one and stay consistent.

Step 1: Gem + database.yml

# Gemfile
gem "activerecord-tenanted"

# config/database.yml — every environment
primary:
  adapter: sqlite3
  database: storage/tenants/<%= Rails.env %>/%{tenant}/main.sqlite3
  tenanted: true
  max_connection_pools: 50
global:
  adapter: sqlite3
  database: storage/<%= Rails.env %>.sqlite3
  migrations_paths: db/global_migrate
queue:
  adapter: sqlite3
  database: storage/<%= Rails.env %>_queue.sqlite3
  migrations_paths: db/queue_migrate
# cache + cable the same way

%{tenant} is the gem's placeholder. database_tasks: false on primary is optional (Herald sets it so Rails doesn't try to dump a single primary schema).

Migrations:

• db/global_migrate/ — Identity, Tenant/Account, Membership, Session. Run once.
• db/migrate/ — tenanted tables. The gem runs these per tenant.

bin/rails db:migrate          # tenanted
bin/rails db:migrate:global    # global — check the gem's task name in the app

Step 2: Two abstract classes

# app/models/application_record.rb
class ApplicationRecord < ActiveRecord::Base
  primary_abstract_class
  tenanted
end

# app/models/global_record.rb
class GlobalRecord < ActiveRecord::Base
  self.abstract_class = true
  connects_to database: { writing: :global, reading: :global }
end

New model: if it is a person, session, or the tenant row itself → GlobalRecord. If it is data inside a workspace → ApplicationRecord. Getting this wrong is the #1 bug.

Step 3: Disable subdomain resolver + default tenant

Path-based apps (all of ours) must not use the gem's subdomain resolver:

# config/initializers/tenanted.rb
Rails.application.configure do
  config.active_record_tenanted.tenant_resolver = ->(request) { nil }
  config.active_record_tenanted.default_tenant =
    Rails.env.local? ? "#{Rails.env}-tenant" : nil
  config.active_record_tenanted.tenanted_rails_records = true
  config.active_record_tenanted.connection_class = "ApplicationRecord"
end

Production default_tenant must be nil. Otherwise boot can fail with ARTENANT not set, or worse, every request shares one leftover shard. Locally a named default tenant lets console/tests boot.

tenanted_rails_records = true stores Active Storage / Action Text in the tenant DB with prefixed keys. Pair with the active-storage-multitenant skill.

Step 4: Current swaps the shard

class Current < ActiveSupport::CurrentAttributes
  attribute :identity, :session
  attribute :tenant  # or :account — pick one name and use it everywhere
  attribute :user

  def tenant=(tenant)
    super
    return if ActiveRecord::Base.shard_swapping_prohibited?

    ApplicationRecord.current_tenant =
      tenant ? tenant.external_id : ActiveRecord::Tenanted::Tenant::UNTENANTED_SENTINEL
  end
end

Herald uses Current.account= and account.tenant_key ("account-#{id}"). Cortex/Innkeeper use Current.tenant= and tenant.external_id. Same mechanism.

Reset on request end (Cortex):

resets do
  next if ActiveRecord::Base.shard_swapping_prohibited?
  ApplicationRecord.current_tenant = ActiveRecord::Tenanted::Tenant::UNTENANTED_SENTINEL
end

Step 5: Resolve tenant from the URL

Do this in a controller concern, not the gem resolver:

module TenantScoping
  extend ActiveSupport::Concern

  included do
    before_action :set_current_tenant
    before_action :set_current_user
  end

  def set_current_tenant
    record = Tenant.find_by(external_id: params[:tenant_external_id])
    Current.tenant = record if record
  end

  def set_current_user
    return unless Current.identity && Current.tenant
    Current.user = User.find_by(identity_id: Current.identity.id)
  end
end

Routes nest under the tenant key (/:tenant_external_id/... or a project slug that loads Account). Unauthenticated pages (sign-in, webhooks from vendors) skip this and wrap only the tenanted work.

Create the tenant database when the Tenant/Account is created:

after_create :provision_tenant_database

def ensure_tenant_database!
  ApplicationRecord.create_tenant(tenant_key) unless database_exists?
rescue ActiveRecord::Tenanted::TenantExistsError
  # parallel tests / retries
end

Step 6: Jobs, rake, console

def perform(tenant_external_id, record_id)
  ApplicationRecord.with_tenant(tenant_external_id) do
    Current.tenant = Tenant.find_by(external_id: tenant_external_id)
    Record.find(record_id).do_work
  end
end

Never serialize a tenanted Active Record as a GID and expect perform to load it — the job runs untenanted. Pass the global tenant key plus the record id.

Rake / one-off:

Tenant.find_each do |tenant|
  ApplicationRecord.with_tenant(tenant.external_id) do
    puts Project.count
  end
end

Public inbound webhooks with no tenant in the URL: iterate tenants (Innkeeper) or look up a global token that points at a tenant, then with_tenant. Don't query User at the top of the job.

Tests

Every test that touches tenanted models must set a tenant. Use a helper:

def with_tenant(tenant = tenants(:acme), &block)
  ApplicationRecord.with_tenant(tenant.external_id, &block)
end

Integration tests: hit a URL that includes the tenant prefix so TenantScoping runs. Don't stub Current.tenant and then assert on HTTP — the shard won't match the request.

Anti-Patterns

1. acts_as_tenant :workspace in an app that's already tenanted — two tenancy systems. Nebula is the other model; don't mix.
2. Putting Identity or Session on ApplicationRecord — those tables must survive switching shards.
3. User.find in a job without with_tenant — silent empty results or TenantNotSet.
4. Leaving the subdomain resolver on — path-based apps resolve the wrong tenant or none.
5. default_tenant in production — every process shares one database file.
6. Assuming integer PKs in tenant DBs — our tenanted tables are UUIDs. See uuid-primary-keys.
7. Creating blobs without a current tenant — "Cannot generate a Blob key without a tenant." Use with_tenant and the Active Storage skill.

Related

• Identity vs User, memberships, join codes: identity-membership
• Tenanted Active Storage / Lexxy: active-storage-multitenant
• Outbound webhooks that run in a tenant: outgoing-webhooks
• Passwordless sign-in (global Identity): magic-link-auth

See reference.md for database.yml, Herald vs Cortex naming, and shard-swap gotchas.