User Guide

Usage as Python library

This project is usable as a Python library.

Install the latest version of the project from PyPI:

pip install -U cdn-definitions

CDN definitions may then be accessed via a few methods in the cdn_definitions module, as in example:

from cdn_definitions import load_data

DATA = load_data(source="https://raw.githubusercontent.com/release-engineering/cdn-definitions/master/src/cdn_definitions/data.json")
for alias in DATA["rhui_alias"]:
  if my_path.startswith(alias["src"]):
    # my path falls under a /rhui/ alias,
    # so now do something special

If a source is not specified, the library will use data from the first existing of the following sources:

  • A JSON or YAML file pointed at by the CDN_DEFINITIONS_PATH environment variable.

  • The file bundled with the library on PyPI.

  • /usr/share/cdn-definitions/data.yaml.

Note that loading from the release-engineering/cdn-definitions repo as seen above will yield placeholder/reference data. This reference data aims to give a general idea of the data’s structure and purpose, and also enable automated testing within downstream projects consuming cdn-definitions.

However, in production scenarios it will be necessary to deploy your code pointing at a genuine data set. This will typically be accomplished either by calling load_data passing the URL of an internal data set, or ensuring that CDN_DEFINITIONS_PATH is set appropriately where your code is deployed.

Python reference

cdn_definitions.load_data(source=None, session=None)

Loads data from a YAML or JSON file into a Python object. If a requests.Session is provided in the “session” parameter, any HTTP request issued while loading data will use the given session.

Parameters:

  • source (str, optional) – A local path or URL to a JSON or YAML data file.

  • session (requests.Session, optional) – A session to provide to HTTP requests.

Returns:

The data from the local path or URL, coerced into a Python object.

Raises:

RuntimeError – If all attempted data sources are invalid, a RuntimeError will be raised.

cdn_definitions.load_schema()

Loads the schema.json file provided with the cdn-definitions package into a Python object.

Returns:

The cdn-definitions schema, coerced into a Python object.