To customize the output fields for the kubectl get command when working with Operator-SDK, you can use the additionalPrinterColumns configuration in your Operator's Custom Resource Definition (CRD) manifest.

Here's an example of how you can add additional printer columns to your CRD:

1. Open the CRD file for your Operator, typically named <your-operator>.crd.yaml.

2. Locate the spec section of your CRD manifest.

3. Add the additionalPrinterColumns field under the spec section. It should be an array of objects, where each object represents a printer column definition. Here's an example:

spec:

  ...

  additionalPrinterColumns:

    - name: MyColumn1

      type: string

      description: A custom column for my resource

      JSONPath: .spec.myField1

    - name: MyColumn2

      type: string

      description: Another custom column

      JSONPath: .status.myField2

In this example, we define two additional printer columns: MyColumn1 and MyColumn2. The name field specifies the column name, type defines the data type of the column, description provides a description for the column, and JSONPath specifies the path to the field in the resource to be displayed.

4. Save the changes to the CRD file.

5. Apply the updated CRD manifest to your cluster using kubectl apply -f <your-operator>.crd.yaml.

6. After applying the changes, you can use kubectl get with your custom columns. For example:
kubectl get <resource> -o=custom-columns=NAME:.metadata.name,MY_FIELD1:.spec.myField1,MY_FIELD2:.status.myField2

Replace <resource> with the name of the resource you want to retrieve. In the example above, we used NAME as the column name for the resource's name field, MY_FIELD1 for the custom field myField1 under the spec section, and MY_FIELD2 for the custom field myField2 under the status section.

By configuring additionalPrinterColumns in your CRD, you can define and display custom columns when using kubectl get for your Operator's resources.