Skip to main content
This is a pre-production deployment of Warehouse. Changes made here affect the production instance of PyPI (
Help us improve Python packaging - Donate today!

Load a value from an environmental variable, YAML/JSON file, or default to a provided value.

Project Description

Load a value from an environmental variable, YAML/JSON file, or default to a provided value.

Getting chainload


pip install chainload

Install requirements

pip install -r requirements.txt


python install

Using chainload

If you have variables that exist in a file, I recommend assigning a file object to a variable, then passing that variable to the chain loading method.


$ python
>>> from chainload import chainload
>>> variable_file = chainload.load_file(file_name="tests/test_settings.yaml")
>>> chainload.chain_load_variable("environment", "environment", "debug", variable_file)

or, if you have a lot of variables to load, use the class-based approach:

$ python
>>> chainer = chainload.ChainloadSetup(filename="tests/test_settings.yaml", environment_variable_prefix="webapp_")
>>> environment_value = chainer("environment")

the latter has the advantage of being far more DRY for larger use-cases.

See the docstring for chain_load_variable, but this will load a variable in order of:

  1. A default value

  2. From file object

  3. From an environment variable.

    Optional: If the environmental variable is None, and the specified file option name exists in the env, and this behavior is enabled, an attempt to load from an environmental variable of the same name as specified for #2

Running tests

If you want to run the tests for this package:

$ make test
python test
running nosetests
running egg_info
writing chainload.egg-info/PKG-INFO
writing top-level names to chainload.egg-info/top_level.txt
writing dependency_links to chainload.egg-info/dependency_links.txt
reading manifest file 'chainload.egg-info/SOURCES.txt'
writing manifest file 'chainload.egg-info/SOURCES.txt'
Ran 9 tests in 0.007s

Filing bugs / issues

When filing a bug report, please include a Short, Self Contained, Correct (Compilable), Example.

New features / Pull requests

If requesting a new feature, please include a well-explained use-case with example usage.

When making a pull request, if new functionality is added, please include appropriate tests.

Release History

Release History

This version
History Node


History Node


History Node


History Node


History Node


Download Files

Download Files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

File Name & Checksum SHA256 Checksum Help Version File Type Upload Date
chainload-1.4.tar.gz (5.4 kB) Copy SHA256 Checksum SHA256 Source May 20, 2016

Supported By

WebFaction WebFaction Technical Writing Elastic Elastic Search Pingdom Pingdom Monitoring Dyn Dyn DNS Sentry Sentry Error Logging CloudAMQP CloudAMQP RabbitMQ Heroku Heroku PaaS Kabu Creative Kabu Creative UX & Design Fastly Fastly CDN DigiCert DigiCert EV Certificate Rackspace Rackspace Cloud Servers DreamHost DreamHost Log Hosting