Overview
The upgrade is implemented with upgrade engines, which are python
modules:
- Host system engine:
- Copies new repositories to Fuel Master node.
- Installs a package and all the required dependencies such as
Puppet manifests, bootstrap images, provisioning images etc.
- OpenStack engine:
- Installs all data required for OpenStack patching.
- Adds new releases using the Nailgun REST API.
This allows the full list of OpenStack releases to be displayed
in the Fuel web UI.