defines install time parameters like component and enablement and namespace, and K8s settings like resources, HPA spec etc. in a structured way.
The simplest customization is to turn components on and off. For example, to turn on cni ([samples/cni-on.yaml](samples/cni-on.yaml):

```yaml
apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
spec:
  components:
    cni:
      enabled: true
```