defines:
  packages:
    type: array
    default: []
    description: Additional packages to be installed at time of bootstrap
  use_venv:
    type: boolean
    default: false
    description: >
      Install charm dependencies (wheelhouse) into a Python virtual environment
      to help avoid conflicts with other charms or libraries on the machine.
  include_system_packages:
    type: boolean
    default: false
    description: >
      If using a virtual environment, allow the venv to see Python packages
      installed at the system level.  This reduces isolation, but is necessary
      to use Python packages installed via apt-get.