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A cross-platform packaging system that can build and install multiple version of packages, and dynamically configure resolved environments at runtime.

Project description


Rez is a cross-platform, LGPL Licensed python library and set of utilities for building and installing packages, and resolving environments containing these packages at runtime, avoiding version conflicts. The main tools are:

  • rez-env - Creates a configured shell containing a set of requested packages. Supports bash and tcsh, and mimics the startup sequences of the native shell.
  • rez-build - Builds a package of any type (python, C++ etc), and installs it locally for testing. Supports cmake.
  • rez-release - Builds and centrally deploys a package, and updates the associated source control repository (creating tags etc). Supports git, mercurial and svn.

Unlike many packaging systems, Rez is able to install many different versions of the same packages. When you use the rez-env tool, a new environment is dynamically created, containing the requested packages. Rez resolves environments at runtime, rather than install time - however, you are able to store a resolve to disk, and reuse it at a later date.

Here’s an example which places the user into a resolved shell containing the requested packages:

]$ rez-env requests-2.2+ python-2.6 'pymongo-0+<2.7'

You are now in a rez-configured environment.

resolved by, on Wed Feb 26 15:56:20 2014, using Rez v2.0.0

implicit packages:

requested packages:

resolved packages:
python-2.6.8    /software/ext/python/2.6.8
platform-linux  /software/ext/platform/linux
requests-2.2.1  /software/ext/requests/2.2.1/python-2.6
pymongo-2.6.3   /software/ext/pymongo/2.6.3
arch-x86_64     /software/ext/arch/x86_64

> ]$ _

Here’s an example which creates an environment containing the package ‘houdini’ version 12.5 or greater, and runs the command ‘hescape -h’ inside that environment:

]$ rez-env -c 'hescape -h' houdini-12.5+
Usage: hescape [-foreground] [-s editor] [filename ...]
-h: output this usage message
-f: force the use of asset definitions in OTL files on the command line
-s: specify starting desktop by name
-foreground: starts process in foreground

Resolved environments can also be created programmatically:

>>> from rez.resolved_context import ResolvedContext
>>> r = ResolvedContext(["houdini-12.5+", "houdini-0+<13", "java", "!java-1.8+"])
>>> r.print_info()
resolved by, on Wed Feb 26 13:03:30 2014, using Rez v2.0.0

implicit packages:

requested packages:

resolved packages:
java-1.7.21       /software/ext/java/1.7.21
platform-linux    /software/ext/platform/linux
arch-x86_64       /software/ext/arch/x86_64
houdini-12.5.562  /software/ext/houdini/12.5.562
>>> import subprocess
>>> p = r.execute_shell(command='which hescape', stdout=subprocess.PIPE)
>>> stdout,stderr = p.communicate()
>>> print stdout


  • Supports Linux and OSX;
  • Allows for a fast and efficient build-install-test cycle;
  • Creates shells of type: bash, tcsh, other (shells can be added as plugins);
  • Contains a deployment system supporting git, mercurial and svn (as plugins);
  • Environment resolves can be saved to disk and reused at a later date (a bit like VirtualEnv);
  • Highly pluggable, supports five different plugin types to do things from adding new shell types, to adding new build systems;
  • Contains a version resolving algorithm, for avoiding version clashes;
  • Visualises resolved environments in a rendered dot-graph;
  • Packages are found in a search path, so different packages can be deployed to different locations;
  • Supports alphanumeric version numbers;
  • Has a powerful version requirements syntax, able to describe any version range, and a conflict operator for rejecting version ranges;
  • Package ‘variants’ - a way to define different flavors of the same package version, for example a plugin built for multiple versions of the host app;
  • Custom release hooks (such as post-release operations) can be added as plugins;
  • Has a time lock feature, which allows old resolves to be recreated (newer packages are ignored);
  • Package definitions are a single, succinct file;
  • Packages define their effect on the environment (adding to PATH etc) in a platform- and shell- agnostic way, using a dedicated python API;
  • Has a memcached-based caching system, for caching environment resolves.


To install Rez, simply:

pip install rez

Or, to install from source:

python install

To see that it’s working:

]$ rez-env -c 'hello_world' hello_world
Hello Rez World!



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