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
kubectl apply -k github.com/istio/installer/base

#### Output to dirs

The output of the manifest is concatenated into a single file. To generate a directory hierarchy with subdirectory
levels representing a child dependency, use the following command:

```bash
istioctl manifest generate -o istio_manifests
```

Use depth first search to traverse the created directory hierarchy when applying your YAML files. This is needed for