Vendor package

What vendored packages are for

The airflow._vendor package is foreseen for vendoring in packages, that we have to modify ourselves because authors of the packages do not have time to modify them themselves. This is often temporary and once the packages implement fixes that we need, and then we remove the packages from the _vendor package.

All Vendored libraries must follow these rules:

1. Vendored libraries must be pure Python--no compiling (so that we do not have to release multi-platform airflow packages on PyPI).
2. Source code for the libary is included in this directory.
3. License must be included in this repo and in the LICENSE file and in the licenses folder.
4. Requirements of the library become requirements of airflow core.
5. Version of the library should be included in the vendor.md file.
6. No modifications to the library may be made in the initial commit.
7. Apply the fixes necessary to use the vendored library as separate commits - each package separately, so that they can be cherry-picked later if we upgrade the vendored package. Changes to airflow code to use the vendored packages should be applied as separate commits/PRs.
8. The _vendor packages should be excluded from any refactorings, static checks and automated fixes.

Adding and upgrading a vendored package

Way to vendor a library or update a version:

1. Update vendor.txt with the library, version, and SHA256 (pypi provides hashes as of recently)
2. Remove all old files and directories of the old version.
3. Replace them with new files (only replace relevant python packages:move LICENSE )
   • move licence files to licenses folder
   • remove README and any other supporting files (they can be found in PyPI)
   • make sure to add requirements from setup.py to airflow's setup.py with appropriate comment stating why the requirements are added and when they should be removed
4. If you replace previous version, re-apply historical fixes from the “package” folder by cherry-picking them.