Transition guide¶

Transitioning to the new rez-pip should be pretty straight forward. There is differences between the two tools, but there is nothing “major” in terms of installing packages from PyPI.

This page documents the differences between the old and the new rez-pip.

Python 3.7+ only¶

The new rez-pip can only be installed in a Python 3 rez install. You will be able to install packages for Python 3.7+, but not anything older than that.

Argument differences¶

Old rez-pip	New rez-pip	Notes
package (positional)	package(s) (positional)	Now accepts multiple packages. Also accepts paths to wheels but local directory isn’t allowed.
`--python-version`	`--python-version`	Similar but now accepts any valid version range (`2.7\\|3.7+`) which allows to install for multiple Python versions.
`--pip-version`	`--pip`	Pip is now bundled with rez-pip, but `--pip` can be used to specify a different pip zipapp.
`-i`/`--install`	Removed
`-r`/`--release`	Identical
`-p`/`--prefix`	`--prefix`	Defaults to `local_packages_path`.
`-e`/`--extra`	`--`	`--extra` was replaced with trailing `--`. For example `rez-pip ... -- --index-url https://example.com`

Local and editable installs¶

The ability to install a local (from source) package via rez-pip -i . as been removed and will not make it back. The same can be said about editable installs. rez pip2 is a tool to ingest Python packages and convert them into rez packages. It’s not a development tool and has never been designed with local development in mind.

I believe these functionalities would be better implemented and would better serve rez’s users if implemented as a build_system plugin. It would allow for better integration with rez and the user experience would be significantly better than it could with rez pip2.

I also believe that python packaging/rez hybrids are bad and just causes more issues than they solve. The python packaging ecosystem and tools have different objectives and goals than rez and the two don’t necessarily always play well together. This is obviously a very personal opinion, but still an opinion from someone with lots of experience with packaging in general.

Pip is now bundled/vendored¶

The previous rez-pip had a complex logic to find both Python and pip. It was error prone, confusing and also annoying to setup.

The new rez pip2 bundles pip, which means it’s ready to be used as is without any extra work/steps. We bundle the standalone zip application which is extremely convenient because it’s a single file.

Bundling has multiple advantages:

We control the version of pip used. This is important to ensure rez-pip works as expected.
No setup required after installation of rez-pip.

If somehow you want or need to change the version of pip used, you can user the rez pip2 --pip command-line argument. You need to provide a path to a zipapp.