What Are Custom Resource Definitions (CRDs)?

Custom Resource Definitions (CRDs) are extensions to the Kubernetes API that enables the creation of custom resources. While Kubernetes comes with a fixed predefined useful resource kind as pods, deployments, and offerings, CRDs permit customers to create their own resource types and controllers.

CRDs introduce new API endpoints to the Kubernetes API server, which allows customers to interact with and control their custom resources through the use of familiar Kubernetes tools and workflows. This feature lets in the seamless integration of custom resources into the Kubernetes ecosystem. 

Custom resources are the heart of CRDs. They provide a way to outline and represent new abstractions within a Kubernetes cluster. With custom sources, software developers can encapsulate complicated logic and domain-specific capability into Kubernetes-native objects. It can be used to represent many different concepts, which include databases, message queues, machine learning models, or entire applications. Developers may successfully manage and operate their custom abstractions by creating custom resources that can take advantage of the robust tooling and rich Kubernetes ecosystem.

The integrated resources in Kubernetes, such as pods, services, and volumes, provide everyday functions for common-use instances. However, you can not use them on your precise and unique requirements. This is wherein CRDs come into the picture.

As the popularity of Kubernetes maintains to grow, so does the need for customizing and extending its competencies. CRDs stands for Custom Resource Definition. The name is self-explanatory. You can use CRDs to construct your custom resource when you have a particular requirement or use case no longer blanketed by means of the integrated resources. Custom Resource Definitions (CRDs) have emerged as a powerful mechanism to outline custom resources inside a Kubernetes cluster. In this article, we are able to explore CRDs, their importance, and how they empower developers and operators to create custom resources tailored to their needs.