rez

What rez provides

Rez is a cross platform package manager with a difference. Using Rez you create standalone environments configured for a given set of packages. Unlike many package managers, packages are not installed into those environments. Instead, all package versions live in a central repository, and the standalone environments reference the existing packages. This makes configured environments lightweight and very fast to create, often taking just a few seconds even when they contain hundreds of packages. Rez takes a list of package requests and constructs the target environment, resolving all necessary dependencies. Any type of software package is supported: compiled binaries, Python modules, applications, and libraries. Each package has a single concise definition file called package.py that declares its dependencies, the commands that configure the environment containing it, and other metadata. When an environment is created with the rez API or the rez-env tool, a dependency resolution algorithm tracks requirements and resolves to a list of needed packages, then concatenates and evaluates their commands. Resolves can be saved to a file and later re-evaluated to rebuild the same environment. The README notes that Rez is able to configure environments with hundreds of packages, often within a few seconds, which is the property that makes it popular in production pipelines where many tools must coexist.

Licensing and distribution

Rez is distributed under the Apache 2.0 license, as shown by the license badge in the README. It is hosted under the Academy Software Foundation, which the repository name AcademySoftwareFoundation and the ASWF Slack and mailing list links make clear. The project publishes releases to PyPI, and the README carries a PyPI release badge alongside a GitHub release badge, so users can track versions through either channel. The README points to the wiki at rez.readthedocs.io for full documentation, and the docs are also built on readthedocs with a stable badge. Rez is not installed like a normal Python package. The quickstart says to download the source and run python3 dot slash install.py minus v DEST_DIR from the source directory, which installs the command line tools. The README warns not to move the installation afterward and to reinstall if the path must change, and it notes that separate installs are needed for multiple operating systems. Because Rez manages its own central repository of package versions, the Apache 2.0 license applies to Rez itself, while each packaged piece of software keeps its own license. The project also links SonarCloud, codecov, and OpenSSF best practices badges, signaling attention to code quality and supply chain health.

Community and contribution process

Rez is developed in the open under the Academy Software Foundation, and the README lists several ways to reach the developers. Bugs and help requests go through GitHub issues, real time chat happens in the ASWF Slack in the hash rez channel, and broader conversations use GitHub discussions or the rez discussion mailing list. The mailing list is described as less active than the other channels, so new users should prefer Slack or discussions. The README also states that Rez supports Linux, OSX, and Windows, and that it is highly pluggable with five plugin types for adding shell types, build systems, and more. A known issue is called out directly: CMake builds do not function on Windows with Rez, and the related tests are skipped while a fix is on the roadmap. That kind of explicit limitation note is part of how the project communicates with its community. Contributors work through pull requests against the main branch, and the README links a CONTRIBUTING.md with guidelines. The combination of a public issue tracker, a chat room, a discussion forum, and published quality metrics gives users multiple paths to report problems and propose changes, which is typical of an ASWF governed project that aims for broad industry adoption.

Editorial conclusion

Rez is licensed under Apache 2.0 and maintained under the Academy Software Foundation, with releases on PyPI and documentation on readthedocs. It installs from source with python3 install.py and is not a normal pip package.