To install Custom Resource Definitions (CRDs) in Kubernetes, you typically define them in a YAML file and then apply that file using kubectl. CRDs allow you to extend the Kubernetes API by defining your own resources.
Here’s a step-by-step guide to install CRDs:
Step 1: Create a CRD YAML File
Create a YAML file that defines your CRD. Below is an example of a CRD YAML definition for a MyCustomResource:
apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
name: mycustomresources.mygroup.example.com
spec:
group: mygroup.example.com
versions:
- name: v1
served: true
storage: true
schema:
openAPIV3Schema:
type: object
properties:
spec:
type: object
properties:
someField:
type: string
scope: Namespaced
names:
plural: mycustomresources
singular: mycustomresource
kind: MyCustomResource
shortNames:
- mcr
This defines a CRD called MyCustomResource, which is scoped to a namespace and has a field someField.
Step 2: Install the CRD using kubectl
Once you’ve defined your CRD YAML file, you can install it using the kubectl command. Assuming the file is called mycustomresource-crd.yaml, you can install it like this:
kubectl apply -f mycustomresource-crd.yaml
Step 3: Verify the CRD is Installed
To verify the CRD has been installed successfully, you can use:
kubectl get crds
You should see mycustomresources.mygroup.example.com in the list of CRDs.
Step 4: Create Custom Resources
Once the CRD is installed, you can now create Custom Resources (CRs) based on that CRD. Here’s an example of a custom resource using the CRD:
apiVersion: mygroup.example.com/v1
kind: MyCustomResource
metadata:
name: my-custom-resource-instance
spec:
someField: "Some value"
To create this custom resource, save the YAML to a file (e.g., my-custom-resource.yaml) and apply it:
kubectl apply -f my-custom-resource.yaml
