Kubernetes Objects & Resources

Objects and Resources¶

In Kubernetes, any item that a user creates and retains is referred to as an Object.
- These can include various items such as namespaces, pods, deployments, volumes, or secrets.
- Any object you create, gets stored in etcd.
etcd stores all objects under the key named /registry directory.
- For instance, details regarding a pod called Nginx in the default namespace can be retrieved by searching for /registry/pods/default/nginx.
To create objects, you describe what you want (desired state) in a file using either YAML or JSON.
- It is called a Object Specification (pod, deployment, etc definition file).

In Kubernetes, everything is accessed through APIs.

To create different types of objects such as pods, namespaces, configmaps etc, Kubernetes API server provides API endpoints.
- These object-specific endpoints are called API resources or resources.
- For example, the API endpoint used to create a pod is referred to as a Pod resource.
In simpler terms, a resource is a specific API URL used to access an object, and they can be accessed through HTTP verbs such as GET, POST, and DELETE.
- For instance, the /api/v1/pods resource can be used to retrieve a list of Pod objects, and an individual Pod object can be obtained from the /api/v1/namespaces/pods/ resource.
Every Kubernetes resource has a Group, Version and Kind that uniquely identifies it.

Resources are like blueprints or templates for Kubernetes objects, while objects are actual instances created from those blueprints that are running in the Kubernetes cluster.

When creating a Kubernetes object using kubectl, the YAML specification is converted to JSON format and sent to the Pod resource (Pod API endpoint).

References¶

Kubernetes Objects Vs Resources Vs Custom Resource (devopscube.com)

Last updated: 2023-05-08