Description of change
Upgrade series worker for observing status notifications and manipulating unit agents. - Adds a new API with methods necessary for accessing the upgrade-series lock statuses. - Adds a new upgrade-series worker. - Adds a new manifold for the worker.
The worker will detect when units have completed their upgrade-series preparation, stop them, restart them and transition through to a completed status.
This patch also introduces a worker testing pattern that I think may be interesting for future use.
QA steps
- Unit tests.
- End-to-end testing of the upgrade-series tracer bullet is TBC.
Documentation changes
None.
Bug reference
N/A
该提问来源于开源项目：juju/juju
