Integrate Ruff into Your Python Application and CI Pipeline: Step-by-Step Guide with Benchmarks

todo_app/
├── app/
│   ├── __init__.py
│   ├── main.py
│   └── utils.py
├── tests/
│   └── test_main.py
├── pyproject.toml
├── requirements.txt
└── .github/
    └── workflows/
        └── lint.yml

from app.utils import add_task, list_tasks

def main():
    print("Welcome to the To-Do App")
    add_task("Learn Ruff")
    add_task("Integrate Ruff in CI")
    print("Your Tasks:")
    for task in list_tasks():
        print(f"- {task}")

if __name__ == "__main__":
    main()

tasks = []

def add_task(task: str):
    """Add a task to the list."""
    if not task:
        raise ValueError("Task cannot be empty")
    tasks.append(task)

def list_tasks():
    """Return all tasks."""
    return tasks

from app.utils import add_task, list_tasks

def test_add_task():
    add_task("Task 1")
    assert "Task 1" in list_tasks()

pip install ruff

ruff --version

[tool.ruff]
# Maximum line length (similar to Black’s default)
line-length = 88

# Specify Python version for compatibility
target-version = "py311"

# Select rulesets to enforce
# Common rule groups:
#   E/F = Pycodestyle (errors & warnings)
#   W = general warnings
#   I = import sorting
#   UP = pyupgrade rules (modernize code)
#   N = naming conventions
select = ["E", "F", "W", "I", "UP"]

# Ignore specific rule codes if desired
ignore = [
    "E501",  # ignore line length errors (if you rely on Black)
]

# Exclude certain paths (like virtualenvs or migrations)
exclude = ["venv", "build", "__pycache__", "migrations"]

# Show fixes when applying --fix
show-fixes = true

# Respect .gitignore patterns
respect-gitignore = true

# Auto-detect per-file ignores if necessary
per-file-ignores = { "tests/test_*.py" = ["S101"] }

# Enable incremental mode (optional, speeds up re-runs)
cache-dir = ".ruff_cache"

[tool.ruff.lint.isort]
# Sort imports intelligently
known-first-party = ["app"]
combine-as-imports = true

repos:
  - repo: https://github.com/astral-sh/ruff-pre-commit
    rev: v0.6.15
    hooks:
      - id: ruff
        args: [--fix]
      - id: ruff-format

pip install pre-commit
pre-commit install

name: Ruff Linting CI

on:
  push:
    branches: [ main ]
  pull_request:
    branches: [ main ]

jobs:
  lint:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout code
        uses: actions/checkout@v4

      - name: Set up Python
        uses: actions/setup-python@v5
        with:
          python-version: "3.11"

      - name: Install Ruff
        run: pip install ruff

      # 🔹 Recommended: lint the code (no fixes)
      - name: Run Ruff Linter
        run: ruff check . --output-format=github

      # 🔹 Optional: Check formatting
      - name: Check Ruff Formatting
        run: ruff format --check .

ruff check .        # Lint check
ruff check . --fix  # Auto-fix issues
ruff format .       # Format code
pytest              # Run tests