all CRDs to be present. On each upgrade it is recommended to reapply the file, to make sure
you get all CRDs.  CRDs are separated by release and by component type in the CRD directory.

Istio has strong integration with certmanager.  Some operators may want to keep their current certmanager
CRDs in place and not have Istio modify them. In this case, it is necessary to apply CRD files individually.

```bash

from the in-cluster IstioOperator custom resource (CR).
There are two major differences:

1. The controller does not accept any dynamic user config through flags. All user interaction is through the
IstioOperator CR.
1. The controller has additional logic that mirrors istioctl commands like upgrade, but is driven from the declarative
API rather than command line.

### Quick tour of CLI commands