Accessing Briefcase packaging metadata at runtime

When Briefcase installs your app, it adds a PEP566 metadata file containing information about your app, and Briefcase itself. You can retrieve this information at runtime using the Python builtin library ‘importlib.metadata’. importlib.metadata was added in Python 3.8; however, it has been backported and published on PyPI as ‘importlib_metadata’ for older versions of Python.

To access application metadata at runtime, you can use the following code:

import sys
try:
    from importlib import metadata as importlib_metadata
except ImportError:
    # Backwards compatibility - importlib.metadata was added in Python 3.8
    import importlib_metadata

# Find the name of the module that was used to start the app
app_module = sys.modules['__main__'].__package__
# Retrieve the app's metadata
metadata = importlib_metadata.metadata(app_module)

The metadata returned by this code will be a dictionary-like object that contains the following identifying keys:

  • Metadata-Version - The syntax version of the metadata file itself (as defined in PEP566).
  • Briefcase-Version - The version of Briefcase used to package the app. The existence of this key in app metadata can be used to identify if your application code is running in a Briecase container; it will only exist if the app has been packaged by Briefcase.

It will also have the following keys, derived from your application’s pyproject.toml configuration:

  • Name - app_name
  • Formal-Name - formal_name
  • App-ID - bundle and app_name, joined with a .
  • Version - version
  • Summary - description

The metadata may also contain the following keys, if they have been defined in your app’s pyproject.toml configuration:

  • Home-page - url
  • Author - author
  • Author-email - author_email

For example, the metadata for the app constructed by the Beeware Tutorial would contain:

Metadata-Version: 2.1
Briefcase-Version: 0.3.1
Name: helloworld
Formal-Name: Hello World
App-ID: com.example.helloworld
Version: 0.0.1
Home-page: https://example.com/helloworld
Author: Jane Developer
Author-email: jane@example.com
Summary: My first application