Static code checks

The static code checks in Airflow are used to verify that the code meets certain quality standards. All the static code checks can be run through pre-commit hooks.

The pre-commit hooks perform all the necessary installation when you run them for the first time. See the table below to identify which pre-commit checks require the Breeze Docker images.

You can also run some static code check via Breeze environment using available bash scripts.

Pre-commit hooks

Pre-commit hooks help speed up your local development cycle and place less burden on the CI infrastructure. Consider installing the pre-commit hooks as a necessary prerequisite.

The pre-commit hooks by default only check the files you are currently working on and make them fast. Yet, these checks use exactly the same environment as the CI tests use. So, you can be sure your modifications will also work for CI if they pass pre-commit hooks.

We have integrated the fantastic pre-commit framework in our development workflow. To install and use it, you need at least Python 3.8 locally.

Installing pre-commit hooks

It is the best to use pre-commit hooks when you have your local virtualenv for Airflow activated since then pre-commit hooks and other dependencies are automatically installed. You can also install the pre-commit hooks manually using pip install.

pip install pre-commit

After installation, pre-commit hooks are run automatically when you commit the code and they will only run on the files that you change during your commit, so they are usually pretty fast and do not slow down your iteration speed on your changes. There are also ways to disable the pre-commits temporarily when you commit your code with --no-verify switch or skip certain checks that you find to much disturbing your local workflow. See Available pre-commit checks and Using pre-commit

The current list of prerequisites is limited to xmllint:

• on Linux, install via sudo apt install libxml2-utils
• on macOS, install via brew install libxml2

Some pre-commit hooks also require the Docker Engine to be configured as the static checks are executed in the Docker environment (See table in the Available pre-commit checks . You should build the images locally before installing pre-commit checks as described in BREEZE.rst.

Sometimes your image is outdated and needs to be rebuilt because some dependencies have been changed. In such cases, the Docker-based pre-commit will inform you that you should rebuild the image.

In case you do not have your local images built, the pre-commit hooks fail and provide instructions on what needs to be done.

Enabling pre-commit hooks

To turn on pre-commit checks for commit operations in git, enter:

pre-commit install

To install the checks also for pre-push operations, enter:

pre-commit install -t pre-push

For details on advanced usage of the install method, use:

pre-commit install --help

Available pre-commit checks

This table lists pre-commit hooks used by Airflow. The Image column indicates which hooks require Breeze Docker image to be built locally.

ID	Description	Image
black	Run black (Python formatter)
blacken-docs	Run black on Python code blocks in documentation files
check-aiobotocore-optional	Check if aiobotocore is an optional dependency only
check-airflow-config-yaml-consistent	Check consistency between config.yml and default_config.cfg
check-airflow-provider-compatibility	Check compatibility of Providers with Airflow
check-apache-license-rat	Check if licenses are OK for Apache
check-base-operator-partial-arguments	Check BaseOperator and partial() arguments
check-base-operator-usage	Check BaseOperator[Link] core imports Check BaseOperator[Link] other imports
check-boring-cyborg-configuration	Checks for Boring Cyborg configuration consistency
check-breeze-top-dependencies-limited	Breeze should have small number of top-level dependencies
check-builtin-literals	Require literal syntax when initializing builtin types
check-changelog-has-no-duplicates	Check changelogs for duplicate entries
check-core-deprecation-classes	Verify usage of Airflow deprecation classes in core
check-daysago-import-from-utils	Make sure days_ago is imported from airflow.utils.dates
check-decorated-operator-implements-custom-name	Check @task decorator implements custom_operator_name
check-docstring-param-types	Check that docstrings do not specify param types
check-example-dags-urls	Check that example dags url include provider versions
check-executables-have-shebangs	Check that executables have shebang
check-extra-packages-references	Checks setup extra packages
check-extras-order	Check order of extras in Dockerfile
check-for-inclusive-language	Check for language that we do not accept as community
check-hooks-apply	Check if all hooks apply to the repository
check-incorrect-use-of-LoggingMixin	Make sure LoggingMixin is not used alone
check-init-decorator-arguments	Check model __init__ and decorator arguments are in sync
check-lazy-logging	Check that all logging methods are lazy
check-links-to-example-dags-do-not-use-hardcoded-versions	Verify example dags do not use hard-coded version numbers
check-merge-conflict	Check that merge conflicts are not being committed
check-newsfragments-are-valid	Check newsfragments are valid
check-no-airflow-deprecation-in-providers	Do not use DeprecationWarning in providers
check-no-providers-in-core-examples	No providers imports in core example DAGs
check-no-relative-imports	No relative imports
check-only-new-session-with-provide-session	Check NEW_SESSION is only used with @provide_session
check-persist-credentials-disabled-in-github-workflows	Check that workflow files have persist-credentials disabled
check-pre-commit-information-consistent	Validate hook IDs & names and sync with docs
check-provide-create-sessions-imports	Check provide_session and create_session imports
check-provider-yaml-valid	Validate provider.yaml files
check-providers-init-file-missing	Provider init file is missing
check-providers-subpackages-init-file-exist	Provider subpackage init files are there
check-pydevd-left-in-code	Check for pydevd debug statements accidentally left
check-revision-heads-map	Check that the REVISION_HEADS_MAP is up-to-date
check-safe-filter-usage-in-html	Don't use safe in templates
check-setup-order	Check order of dependencies in setup.cfg and setup.py
check-start-date-not-used-in-defaults	start_date not to be defined in default_args in example_dags
check-system-tests-present	Check if system tests have required segments of code
check-system-tests-tocs	Check that system tests is properly added
check-tests-unittest-testcase	Check that unit tests do not inherit from unittest.TestCase
check-urlparse-usage-in-code	Don't use urlparse in code
check-xml	Check XML files with xmllint
codespell	Run codespell to check for common misspellings in files
compile-www-assets	Compile www assets
compile-www-assets-dev	Compile www assets in dev mode
create-missing-init-py-files-tests	Create missing init.py files in tests
debug-statements	Detect accidentally committed debug statements
detect-private-key	Detect if private key is added to the repository
doctoc	Add TOC for Markdown and RST files
end-of-file-fixer	Make sure that there is an empty line at the end
fix-encoding-pragma	Remove encoding header from Python files
flynt	Run flynt string format converter for Python
identity	Print input to the static check hooks for troubleshooting
insert-license	Add license for all SQL files Add license for all RST files Add license for all CSS/JS/JSX/PUML/TS/TSX files Add license for all JINJA template files Add license for all Shell files Add license for all Python files Add license for all XML files Add license for all Helm template files Add license for all YAML files except Helm templates Add license for all Markdown files Add license for all other files
lint-chart-schema	Lint chart/values.schema.json file
lint-css	stylelint
lint-dockerfile	Lint Dockerfile
lint-helm-chart	Lint Helm Chart
lint-json-schema	Lint JSON Schema files with JSON Schema Lint NodePort Service with JSON Schema Lint Docker compose files with JSON Schema Lint chart/values.schema.json file with JSON Schema Lint chart/values.yaml file with JSON Schema Lint config_templates/config.yml file with JSON Schema
lint-markdown	Run markdownlint
lint-openapi	Lint OpenAPI using spectral Lint OpenAPI using openapi-spec-validator
mixed-line-ending	Detect if mixed line ending is used (r vs. rn)
mypy-core	Run mypy for core
mypy-dev	Run mypy for dev
mypy-docs	Run mypy for /docs/ folder
mypy-providers	Run mypy for providers
pretty-format-json	Format JSON files
python-no-log-warn	Check if there are no deprecate log warn
replace-bad-characters	Replace bad characters
rst-backticks	Check if RST files use double backticks for code
ruff	ruff
shellcheck	Check Shell scripts syntax correctness
trailing-whitespace	Remove trailing whitespace at end of line
ts-compile-format-lint-www	TS types generation / ESLint / Prettier against UI files
update-black-version	Update black versions everywhere
update-breeze-cmd-output	Update output of breeze commands in BREEZE.rst
update-breeze-readme-config-hash	Update Breeze README.md with config files hash
update-common-sql-api-stubs	Check and update common.sql API stubs
update-er-diagram	Update ER diagram
update-extras	Update extras in documentation
update-in-the-wild-to-be-sorted	Sort INTHEWILD.md alphabetically
update-inlined-dockerfile-scripts	Inline Dockerfile and Dockerfile.ci scripts
update-installed-providers-to-be-sorted	Sort alphabetically and uniquify installed_providers.txt
update-local-yml-file	Update mounts in the local yml file
update-migration-references	Update migration ref doc
update-providers-dependencies	Update cross-dependencies for providers packages
update-spelling-wordlist-to-be-sorted	Sort alphabetically and uniquify spelling_wordlist.txt
update-supported-versions	Updates supported versions in documentation
update-vendored-in-k8s-json-schema	Vendor k8s definitions into values.schema.json
update-version	Update version to the latest version in the documentation
yamllint	Check YAML files with yamllint

Using pre-commit

After installation, pre-commit hooks are run automatically when you commit the code. But you can run pre-commit hooks manually as needed.

• Run all checks on your staged files by using:

pre-commit run

• Run only mypy check on your staged files (in airflow/ excluding providers) by using:

pre-commit run mypy-core

• Run only mypy checks on all files by using:

pre-commit run mypy-core --all-files

• Run all checks on all files by using:

pre-commit run --all-files

• Run all checks only on files modified in the last locally available commit in your checked out branch:

pre-commit run --source=HEAD^ --origin=HEAD

• Show files modified automatically by pre-commit when pre-commits automatically fix errors

pre-commit run --show-diff-on-failure

• Skip one or more of the checks by specifying a comma-separated list of checks to skip in the SKIP variable:

SKIP=mypy-core,ruff pre-commit run --all-files

You can always skip running the tests by providing --no-verify flag to the git commit command.

To check other usage types of the pre-commit framework, see Pre-commit website.

Running static code checks via Breeze

The static code checks can be launched using the Breeze environment.

You run the static code checks via breeze static-check or commands.

You can see the list of available static checks either via --help flag or by using the autocomplete option.

Run the mypy check for the currently staged changes (in airflow/ excluding providers):

breeze static-checks --type mypy-core

Run the mypy check for all files:

breeze static-checks --type mypy-core --all-files

Run the ruff check for the tests/core.py file with verbose output:

breeze static-checks --type ruff --file tests/core.py --verbose

Run the ruff for the ``tests.core package with verbose output:

breeze static-checks --type ruff --file tests/core/* --verbose

Run the black check for the files airflow/example_dags/example_bash_operator.py and airflow/example_dags/example_python_operator.py:

breeze static-checks --type black --file airflow/example_dags/example_bash_operator.py \
    airflow/example_dags/example_python_operator.py

Run all checks for the currently staged files:

breeze static-checks

Run all checks for all files:

breeze static-checks --all-files

Run all checks for last commit:

breeze static-checks --last-commit

Run all checks for all changes in my branch since branched from main:

breeze static-checks -t mypy-core --only-my-changes

More examples can be found in Breeze documentation

Debugging pre-commit check scripts requiring image

Those commits that use Breeze docker image might sometimes fail, depending on your operating system and docker setup, so sometimes it might be required to run debugging with the commands. This is done via two environment variables VERBOSE and DRY_RUN. Setting them to "true" will respectively show the commands to run before running them or skip running the commands.

Note that you need to run pre-commit with --verbose command to get the output regardless of the status of the static check (normally it will only show output on failure).

Printing the commands while executing:

VERBOSE="true" pre-commit run --verbose ruff

Just performing dry run:

DRY_RUN="true" pre-commit run --verbose ruff