Describes the Juju 2.0 serialization format of a model

The description package is a representation of a Juju model. Over the wire format of the Juju model is intended to be yaml.

The design of the description package from the outset supports independent versioning of entities. Each entity can therefor change without rev'ing other entities modelled with in the serialized format.

In this contrived example, it's possible to bump the status entity without bumping the applications. If how ever the entity in question requires a change with application or other entities, those also will need to be bumped.

applications:
  applications:
  - name: ubuntu
    status:
      status:
        message: waiting for machine
      version: 1
  version: 1

The concept of description package in the purest sense, is to ensure that it's possible to encode and decode any entity for the right version. How each version is then correctly implemented is out of scope of the description package.