Purpose¶

You have a layered architecture (presentation → application → domain) and want to enforce that dependencies only flow downward. The domain layer should have no outward dependencies.

Configuration¶

rules:
  - name: domain-isolation
    modules: my_app.domain
    allow:
      standard_library: ["*"]
      third_party: []
      local: [my_app.domain]

  - name: application-layer
    modules: my_app.application
    allow:
      standard_library: ["*"]
      third_party: [pydantic]
      local:
        - my_app.application
        - my_app.domain

  - name: presentation-layer
    modules: my_app.presentation
    allow:
      standard_library: ["*"]
      third_party: [fastapi, pydantic]
      local:
        - my_app.presentation
        - my_app.application
        - my_app.domain

Result¶

If my_app.domain.models imports sqlalchemy:

my_app/domain/models.py:3
    [domain-isolation] my_app.domain.models → sqlalchemy (third_party)

Found 1 violation(s).

If my_app.application.service imports fastapi:

my_app/application/service.py:1
    [application-layer] my_app.application.service → fastapi (third_party)

Found 1 violation(s).