Upgrade Kubernetes Controller Runtime from v0.6.5

This blog concentrates on test case migration as the real code migration pretty detailed and straight forward on official kubernetes websites.

Are you still using version sigs.k8s.io/controller-runtime v0.6.5, time to rethink your choice, as it has costlier bugs that ends up in event failure(s) or misses. The projects that uses the kubernetes operators extensively depends on optimal management of events.

Kubernetes upgrades related to operators usually comes up with breaking this time along with test cases.

The reactors were once been handy to test the edge scenarios, as the projects grows, test cases grows exponentially, and when it comes to a method that is removed / unusable from core library however leveraged extensively by dependant or child projects... 😭

stack overflow

Major Hurdle

The reactors are unusable via fakes along with ClientBuilder.

Test Cases

The operators (or) reconciler's test cases are heavily depndent on reactors and it is not a good idea to add those to technical debts or just ignore them.

FakeReactor instead of Reactor

Based on researches digging deep into the kubernetes libraries and some searches, generalized the usage of FakeReactor, that could be imported and used by any project.

How to use

go get github.com/DreamAmbitious/k8s-controller-runtime-fake

• Old client with reactors, would look like below

fakeK8Client.PrependReactor(
		"get",
		"objectKind",
		func(action k8stesting.Action) (bool, runtime.Object, error) {
			return true, nil, errs.New("k8s error")
		}
)

• Replace your reactors as below with FakeReactingCtrlRuntimeClient

mp := make(map[string]ctrlfake.FakeRunTimeMock)
// CRUD methods create/read/update/delete in lower case, kind refers resource object kind of your operator.
mp["method_kind"] = ctrlfake.FakeRunTimeMock{
	MockFunc: func() (client.Object, error) {
		return nil, errs.New("fake output that you're returning")
	},
)
fakeV1alpha1Client := &ctrlfake.FakeReactingCtrlRuntimeClient{
	Client:          reconcilerClient,
	FakeRunTimeMock: mp,
}

🚯 As this is a mock function, it comes up with more power and responsibility.

• Refer kubernetes NewClientBuilder for more info on usage , here is the gist.

initObjects := []runtime.Object{
	// load all the objects, that is required during runtime while testing
}
k8client := fakectrlruntime.NewClientBuilder().WithScheme(fakeRuntimeScheme).WithRuntimeObjects(initObjects...).Build()

Conclusion

The library can be leverage to test the edge and more complex cases.