Get pdl running in your project in three steps.

Step 1: Create a Config File¶

Create .python-dependency-linter.yaml in your project root and define your dependency rules:

rules:
  - name: domain-isolation
    modules: contexts.*.domain
    allow:
      standard_library: [dataclasses, typing]
      third_party: [pydantic]
      local: [contexts.*.domain]

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

This config defines two rules:

• domain-isolation — modules under contexts.*.domain can only import dataclasses, typing, pydantic, and other domain modules.
• application-dependency — modules under contexts.*.application can import any standard library, pydantic, and application or domain modules.

You can also use pyproject.toml. See Configuration for details.

Step 2: Run the Linter¶

From your project root, run:

pdl check

pdl automatically discovers the config file by searching upward from the current working directory.

Step 3: Review the Output¶

Violations are reported with the file path, line number, rule name, and the dependency direction:

contexts/boards/domain/models.py:6
    [domain-isolation] contexts.boards.domain.models → contexts.boards.application.service (local)

contexts/boards/domain/models.py:9
    [domain-isolation] contexts.boards.domain.models → sqlalchemy (third_party)

Found 2 violation(s).

Fix the reported imports and re-run pdl check until no violations remain.

Next Steps¶

• Learn all available config options in Configuration.
• See rule details and pattern options in the Guide.