refactor(kubeclient): consolidate duplicate code

[ivankatliarchuk]

What does it do ?

Create a new pkg/kubeclient package to consolidate duplicate Kubernetes client creation logic, add metrics instrumentation to the events controller, and use the.

TODO

• execute tests on real cluster

How kube client created and shared with different packages

flowchart TD
    A[externaldns.Config] -->|passed to| B[source.NewClientGenerator]
    B -->|creates| C[SingletonClientGenerator]

    C -->|used by| D[buildController]
    C -->|used by| E[buildSource]

    D -->|calls| F[clientGen.EventsClient]
    F -->|returns| G[EventsV1Interface]
    G -->|passed to| H[events.NewEventController]

    E -->|calls| I[source.ByNames]
    I -->|calls| J[clientGen.KubeClient]
    J -->|returns| K[kubernetes.Interface]
    K -->|used by| L[Sources<br/>Service/Ingress/etc]

    subgraph "Shared Client"
        C
        M[clientGen.KubeClient] -->|creates once| N[kubernetes.Clientset]
        F2[clientGen.EventsClient] -->|delegates to| N
        N -->|.EventsV1| G2[EventsV1Interface]

        style N fill:#99ccff
    end

    style C fill:#ffcc99
    style H fill:#99ff99
    style L fill:#99ff99

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Motivation

Currently event generator and source have 2 distinct clients. As a result rate limiting not working as it should on clusters with large ~50k records.

Work relates to

• Add Record Creation Status to Source Object #6030
• previous PR feat(events): raise k8s events with fake provider #5659

More

• Yes, this PR title follows Conventional Commits
• Yes, I added unit tests
• Yes, I updated end user documentation accordingly

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[coveralls]

Pull Request Test Coverage Report for Build 20656426648

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 124 unchanged lines in 5 files lost coverage.
• Overall coverage increased (+0.1%) to 78.905%

---

Files with Coverage Reduction	New Missed Lines	%
openshift_route.go	1	84.29%
events/types.go	9	88.39%
events/controller.go	10	77.33%
execute.go	34	59.88%
store.go	70	44.35%

Totals
Change from base Build 20636734136:	0.1%
Covered Lines:	15807
Relevant Lines:	20033

---

💛 - Coveralls