siteconf 0.1.5

Configures sys.path to include hierarchical Python paths

siteconf

Customizes sys.path based on platform and Python version when Python loads for site-specific configuration.

This sitecustomize.py module plays a crucial role in VFX pipelines by allowing customizations to be applied to the Python environment at startup.

https://docs.python.org/3/library/site.html#module-sitecustomize

Siteconf works best combined with envstack.

Installation

The easiest way to install is with pip:

$ pip install siteconf

Alternatively, to install from the repo follow these steps:

$ git clone https://github.com/rsgalloway/siteconf
$ cd siteconf
$ python setup.py install

Usage

The sitecustomize.py module provides a convenient way to customize the Python environment by executing code before the interpreter begins executing the main script.

Python libraries are resolved in the following order, from most specific to most agnostic:

$ROOT/$ENV/lib/$PLATFORM/python[$PYVERSION]
$ROOT/$ENV/lib/$PLATFORM/python
$ROOT/$ENV/lib/python[$PYVERSION]
$ROOT/$ENV/lib/python

Some defaults have been set for convenience that can be overridden with environment variables.

For example, by default the deployment root is called "tools", the production environment is called "prod" and the development environment is called "dev", so by default on linux sys.path would include:

/mnt/tools/prod/lib/linux/python3
/mnt/tools/prod/lib/linux/python
/mnt/tools/prod/lib/python3
/mnt/tools/prod/lib/python

or on Windows:

X:/tools/prod/lib/win32/python3
X:/tools/prod/lib/win32/python
X:/tools/prod/lib/python3
X:/tools/prod/lib/python

Environment Variables

The following environment variables can be used to customize Python search paths:

Variable	Description
$DEV	add development environment to the search path
$DEV_ENV	override the default development environment name "dev"
$DRIVE_LETTER	override the default Windows drive letter name "Z"
$ENV	add a custom environment to the search path, e.g. "test"
$PLATFORM	override the platform name (win32, linux, osx)
$PROD_ENV	override the default production environment name "prod"
$PYVERSION	Python version (e.g. 2, 3 or 3.11)
$ROOT	Python module deployment path including mount point
$USE_UNC	use UNC paths on Windows

Development Environment

To add development versions of Python libs (supercedes prod):

$ export DEV=1

Now, the dev environment takes precedence over prod, but the prod environment is still in sys.path, just lower down in priority, so anything in dev will override anything else:

/mnt/tools/dev/lib/linux/python3
/mnt/tools/dev/lib/linux/python
/mnt/tools/dev/lib/python3
/mnt/tools/dev/lib/python
/mnt/tools/prod/lib/linux/python3
/mnt/tools/prod/lib/linux/python
/mnt/tools/prod/lib/python3
/mnt/tools/prod/lib/python

To add a custom "test" environment to the Python search path (supercedes all others):

$ export ENV="test"

Custom environments can be useful for testing a developer's test environment.

To get an idea how environment variables can be set to customize the Python search path here is an example that includes a custom env "test" and Python version 3.11 on linux:

$ ENV=test DEPLOY_ROOT=path/to/tools PYVERSION=3.11 python sitecustomize.py 
/mnt/path/to/tools/test/lib/linux/python3.11
/mnt/path/to/tools/test/lib/linux/python
/mnt/path/to/tools/test/lib/python3.11
/mnt/path/to/tools/test/lib/python
/mnt/path/to/tools/prod/lib/linux/python3.11
/mnt/path/to/tools/prod/lib/linux/python
/mnt/path/to/tools/prod/lib/python3.11
/mnt/path/to/tools/prod/lib/python

Deployment

A few notes about deployment of Python modules and packages:

• platform agnostic libs should be deployed to lib
• platform specific libs should be deployed to lib/$PLATFORM
• Python version agnostic libs should be deployed to python
• Python version specific libs should be deployed to python2, python3, python3.11, etc.