[policies] add on-disk preset support

Add the ability for the Policy class to load presets in JSON
format: a PresetDefaults object maps directly to the JSON file
structure: the outer container is a dictionary whose keys are the
names of the contained presets, and each preset may contain a
"name", "desc", "note", and "opts" member.

Methods are provided to load, write, delete, user presets, and
to register policy-defined built-in presets:

  PresetDefaults.write()
  PresetDefaults.delete()
  Policy.register_presets()
  Policy.load_presets()
  policy.add_preset()
  policy.del_preset()

The name is used to select a preset (in the same way as a policy
defined preset), and the description and note give further
information on the preset and its behaviour (for e.g. performance
impact).

The "opts" key maps to a further dictionary mapping sos argument
names to their preset values.

Loaded presets are added to the active policie's presets store
and are available to the user via --preset.

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>

0 files changed, 0 insertions, 0 deletions