CRD and CR¶
CRD¶
CRD is the abbreviation of Custom Resource Definition, which is a built-in native resource type of Kubernetes. It is the definition of a custom resource (CR), which describes what a custom resource is.
CRD can register a new resource with the Kubernetes cluster to extend the capabilities of the Kubernetes cluster. With CRD, you can customize the abstraction of the underlying infrastructure, customize resource types according to business needs, and use the existing resources and capabilities of Kubernetes to define higher-level abstractions through the pattern of Lego blocks.
CR¶
CR is the abbreviation of Custom Resource, it is actually an instance of CRD, and it is a resource description conforming to the field format definition in CRD.
CRDs + Controllers¶
We all know that Kubernetes has a very powerful expansion capability, but only CRD is useless, and it needs the support of a controller (Custom Controller) to reflect the value of CRD, Custom Controller You can listen to the CRUD event of CR to implement custom business logic.
In Kubernetes, it can be said that CRDs + Controllers = Everything.
Please also refer to the official Kubernetes documentation: