Over the course of recent development of the `componentconfigs` package,
it became evident that most of the tests in this package cannot be implemented without
using a component config. As all of the currently supported component configs are
external to the kubeadm project (kubelet and kube-proxy), practically all of the tests
in this package are now dependent on external code.
This is not desirable, because other component's configs may change frequently and
without much of a notice. In particular many configs add new fields without bumping their
versions. In addition to that, some components may be deprecated in the future and many
tests may use their configs as a place holder of a component config just to test some
common functionality.
To top that, there are many tests that test the same common functionality several times
(for each different component config).
Thus a kubeadm managed replacement and a fake test environment are introduced.
The new test environment uses kubeadm's very own `ClusterConfiguration`.
ClusterConfiguration is normally not managed by the `componentconfigs` package.
It's only used, because of the following:
- It's a versioned API that is under the control of kubeadm maintainers. This enables us to test
the componentconfigs package more thoroughly without having to have full and always up to date
knowledge about the config of another component.
- Other components often introduce new fields in their configs without bumping up the config version.
This, often times, requires that the PR that introduces such new fields to touch kubeadm test code.
Doing so, requires more work on the part of developers and reviewers. When kubeadm moves out of k/k
this would allow for more sporadic breaks in kubeadm tests as PRs that merge in k/k and introduce
new fields won't be able to fix the tests in kubeadm.
- If we implement tests for all common functionality using the config of another component and it gets
deprecated and/or we stop supporting it in production, we'll have to focus on a massive test refactoring
or just continue importing this config just for test use.
Thus, to reduce maintenance costs without sacrificing test coverage, we introduce this mini-framework
and set of tests here which replace the normal component configs with a single one (`ClusterConfiguration`)
and test the component config independent logic of this package.
As a result of this, many of the older test cases are refactored and greatly simplified to reflect
on the new change as well. The old tests that are strictly tied to specific component configs
(like the defaulting tests) are left unchanged.
Signed-off-by: Rostislav M. Georgiev <rostislavg@vmware.com>
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