## Step 3. Update istioctl schema

Istioctl uses a [schema](../../operator/pkg/apis/istio/v1alpha1/values_types.proto) to validate the values. Any changes to
the schema must be added here, otherwise istioctl users will see errors.
Once the schema file is updated, run:

```bash
$ make operator-proto
```

This will regenerate the Go structs used for schema validation.

## Step 4. Update the generated manifests

  optional string patchType = 5;

  // AuditAnnotations is an unstructured key value map set by remote admission controller (e.g. error=image-blacklisted).
  // MutatingAdmissionWebhook and ValidatingAdmissionWebhook admission controller will prefix the keys with
  // admission webhook name (e.g. imagepolicy.example.com/error=image-blacklisted). AuditAnnotations will be provided by

}

// IngressPortStatus represents the error condition of a service port
message IngressPortStatus {
  // Port is the port number of the ingress port.
  optional int32 port = 1;

  // Protocol is the protocol of the ingress port.
  // The supported values are: "TCP", "UDP", "SCTP"
  optional string protocol = 2;

  // Error is to record the problem with the service port

  // responseKind describes the group, version, and kind of the serialization schema for the object type this endpoint typically returns.
  // APIs may return other objects types at their discretion, such as error conditions, requests for alternate representations, or other operation specific behavior.
  // This value will be null if an APIService reports subresources but supports no operations on the parent resource

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

The operator validates the configuration and automatically detects syntax errors. If you are
using Helm values that are incompatible, the schema validation used in the operator may reject input that is valid for
Helm.

protobuf encoding. As a result, caching has been introduced, storing the already encoded `protobuf.Any` for a given resource.

This caching depends on declaring all inputs to the given generator as part of the cache key. This is extremely error-prone, as there is nothing preventing generators from consuming inputs that are *not* part of the key. When this happens, different clients will non-deterministically get incorrect configuration. This type of bug has historically resulted in CVEs....

github.com/globalsign/mgo v0.0.0-20181015135952-eeefdecb41b8/go.mod h1:xkRDCp4j0OGD1HRkm4kmhM+pmpv3AKq5SU7GMg4oO/Q=
github.com/go-errors/errors v1.5.1 h1:ZwEMSLRCapFLflTpT7NKaAc7ukJ8ZPEjzlxt8rPN8bk=
github.com/go-errors/errors v1.5.1/go.mod h1:sIVyrIiJhuEF+Pj9Ebtd6P/rEYROXFi3BopGUQ5a5Og=
github.com/go-jose/go-jose/v3 v3.0.3 h1:fFKWeig/irsp7XD2zBxvnmA/XaRWp5V3CBsZXJF7G7k=

  // +listType=atomic
  // +optional
  repeated Validation validations = 3;

  // failurePolicy defines how to handle failures for the admission policy. Failures can
  // occur from CEL expression parse errors, type check errors, runtime errors and invalid
  // or mis-configured policy definitions or bindings.
  //
  // A policy is invalid if spec.paramKind refers to a non-existent Kind.

This can be reading from Kubernetes and writing other objects back, writing to proxies over XDS, etc.

Unfortunately, writing controllers is very error prone, even for seemingly simple cases.
To work around this, Istio has a variety of abstractions meant to make writing controllers easier.

## Clients

Apart from validating the correctness of individual fields, the operator ensure that relationships between values in
different parts of the configuration tree are correct. For example, it's an error to enable a component while its
parent feature is disabled.

## K8s controller

TODO(rcernich).

## Manifest creation

Manifest rendering is a multi-step process, shown in the figure below. ![rendering