How to write own CRD in Kubernetes

"Kubernetes is known for being extensible. If you have ever seen custom objects like ArgoCDApplication, HelmRelease you might have wondered how Kubernetes understands these custom objects. What is a CRD A CRD(Custom Resource Definition) is a built-in Kubernetes feature that lets you extend the Kubernetes API by defining your own resource. A Custom Resource Definition allows you to define a new type of Kubernetes resource. Once installed, you can manage instances of this new resource just like native Kubernetes objects ( kubectl get, apply, delete, etc.)."

"A Simple Analogy: If you are familiar with object-oriented programming, you might be familiar with a concept of classes and objects. A similar analogy can be used here Custom Resource Definition: You can think of a Custom Resource Definition as similar to a class. A class defines the structure and fields but doesn't hold any actual data itself. In the same way, a CRD defines the of a custom resource in Kubernetes."

Custom Resource Definitions (CRDs) are a built-in Kubernetes feature that extend the Kubernetes API by defining new resource types. Once a CRD is installed, instances of the new resource can be managed like native Kubernetes objects using kubectl get, apply, delete, and other commands. Kubernetes supports extensibility with many custom objects such as ArgoCDApplication and HelmRelease. A CRD defines the structure and schema of a custom resource, while a Custom Resource (CR) is an instance created from that definition. The class/object analogy maps a CRD to a class and a CR to an object.

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