cpenv

cpenv

Manage software plugins, project dependencies and environment variables using Modules.

Installation

The recommended method of installing cpenv is via pipx. Pipx is used to install python cli applications in isolation.

pipx install cpenv

pipx upgrade cpenv

pipx uninstall cpenv

Overview

Cpenv is a cli tool and python library used to create, edit, publish, and activate Modules. A Module is a folder containing a dependency, like Arnold for Maya, and a module file that configures it.

Environment Variables

Variable	Description	Default
CPENV_HOME	Customize path to cpenv home
CPENV_DISABLE_PROMPT	Disable prompt when modules activated	0
CPENV_ACTIVE_MODULES	List of activated modules
CPENV_SHELL	Preferred subshell like "powershell"
CPENV_ENABLE_LOCKFILES	Enable lockfiles during localization	0

Example Modules

• snack

Create a Module

Use cpenv create <module> to use a guide to create a new Module. This will create a new folder in your current working directory with a module file in it.

Edit a Module

Each Module contains a module.yml file, referred to as a module file. A module file contains metadata like the name and version of a module, as well as configuration, like environment variables.

# Variables
# $MODULE - path to this module
# $PLATFORM - platform name (win, mac, linux)
# $PYVER - python version (2.7, 3.6...)

# Wrap variables in brackets when they are nested within a string.
#     DO 'this${variable}isnested/' NOT 'this$variableisnested'

name: 'my_module'
version: '0.1.0'
description: 'My first module.'
author: 'Me'
email: '[e-mail]'
requires: []
environment:
    MY_MODULE_VAR: 'Test'

Environment key

Setting a value will insert a key or overwrite it's existing value.

SOME_VAR: 'SOME_VALUE'

Use the $MODULE variable for module relative paths.

RELATIVE_VAR: $MODULE/bin

Use lists to prepend values to a key.

PATH:
    - $MODULE/bin

Use win, linux and mac or osx keys to declare platform specific values. If you leave out a platform, the variable will not be included on that platform.

PLATFORM_VAR:
    mac: /mnt/some/path
    linux: /Volumes/some/path
    win: C:/some/path

You can also use platform keys when prepending values to a variable.

PATH:
    - mac: $MODULE/macattack
      linux: $MODULE/penguin
      win: $MODULE/squares

Reuse environment variables to simplify things.

BASE: $MODULE/$PLATFORM/base
PATH:
    - $BASE/bin
PYTHONPATH:
    - $BASE/python

Advanced

The implicit set and prepend operations above cover the most common use cases when modifying environment variables. For more advanced use cases you can use the following explicit operation keys.

SVAR:
    set:
        - Value0
        - Value1
PVAR:
    prepend:
        - X
RVAR:
    unset: 1
PATH:
    remove:
        - C:/Python27
        - C:/Python27/Scripts
PYTHONPATH:
    append:
        - $MODULE/python
        - $MODULE/lib

You can also uses lists of opreations to perform complex modifications.

PATH:
    - remove: /some/file/path
    - append: /some/other/path
    - prepend: /one/more/path

One workflow that this enables is the use of modules solely for the purpose of overriding environment variables. Imagine you have a module my_tool and it uses a variable MY_TOOL_PLUGINS to lookup plugins.

name: my_tool
...
environment:
    MY_TOOL_PLUGINS:
        - //studio/dev/my_tool/plugins
        - //studio/projects/test_project/plugins

Now imagine you have a new project and you want my_tool to look at a different location for plugins just for that project. Rather than create a new version of the my_tool module, create a override module. We might name this module after our project, project_b.

name: project_b
...
environment:
    MY_TOOL_PLUGINS:
        set:
            - //studio/prod/my_tool/plugins
            - //studio/projects/project_b/plugins

All we have to do is activate my_tool and project_b in that order to make sure our overrides are used.

> cpenv activate my_tool project_b

Requires key

The requires key is a list of dependencies that a module needs to function. Currently this is only used for reference, these modules will not be activated automatically.

Test a Module

When you're working on a module navigate into it's root directory. Then you can activate it using cpenv activate .. This is the best way to validate your module prior to publishing.

Publish a Module

Once you're Module is ready for production, use cpenv publish . to publish it. Publishing a Module uploads it to a Repo of your choosing.

Repos

Repos are storage locations for Modules that support finding, listing, uploading, and downloading Modules via requirements like my_module-0.1.0. Cpenv is configured with the following LocalRepos by default:

• cwd - Your current working directory
• user - A user specific repo
• home - A machine wide repo

Use cpenv repo list to display your configured Repos. LocalRepos point directly to folders on your local file system. Customize the home Repo by setting the CPENV_HOME environment variable.

When you activate a module using a requirement, all configured Repos are searched and the best match is used. If the resolved module is not in a LocalRepo it will be downloaded to your home Repo then activated. This is one of the key features of cpenv and allows for strong distributed workflows. For example, you can configure a remote repo like the ShotgunRepo and store your modules directly in a Shotgun studio database. Visit the tk-cpenv repository for more info on using cpenv with Shotgun

Requirements

Requirements are strings used to resolve and activate modules in Repos. They can be versionless like my_module or require a version like my_module-0.1.0. Cpenv supports semver/calver, simple versions (v1), and what I like to call weird versions like 12.0v2 (The Foundry products). In the future cpenv may support more complex requirements by utilizing resolvelib.

Locking

It may be desirable to have interprocess locking around module localization. One use case I've run into is with Deadline rendering on workers with multiple gpus. In that case, a single worker may be rendering multiple frames simultaneously, and therefore, it's possible that the worked may try to download the same module at the same time. To enable interprocess locking via lockfiles, set the environment variable CPENV_ENABLE_LOCKFILES to 1.