With this in mind, Ztunnel supports two xDS resources: `Address` and `Authorization`.

### Address Type

The primary configuration consumed by Ztunnel is the [`Address` resource](../../pkg/workloadapi/workload.proto).
As the name suggests, an `Address` represents a particular IP Address.
This can be a `Service` or a `Workload`.

Istiod is structured as a modular monolith, housing a wide range of functionality from certificate signing, proxy configuration (XDS), traditional Kubernetes controllers, and more.

## Proxy Configuration

Istiod's primary role - and most code - is to dynamically configure proxies (Envoy sidecars and ingress, gRPC, ztunnel, and more). This roughly consists of 3 parts:
1. Config ingestion (inputs to the system)
1. Config translation

		"Suppress reporting a message code on a specific resource. Values are supplied in the form "+
			`<code>=<resource> (e.g. '--suppress "IST0102=DestinationRule primary-dr.default"'). Can be repeated. `+
			`You can include the wildcard character '*' to support a partial match (e.g. '--suppress "IST0102=DestinationRule *.default" ).`)

    neverInjectSelector: []
    alwaysInjectSelector: []

    # injectedAnnotations are additional annotations that will be added to the pod spec after injection
    # This is primarily to support PSP annotations. For example, if you defined a PSP with the annotations:
    #
    # annotations:
    #   apparmor.security.beta.kubernetes.io/allowedProfileNames: runtime/default

// the DaemonSet and StatefulSet controllers for update and rollback, this object is beta. However,
// it may be subject to name and representation changes in future releases, and clients should not
// depend on its stability. It is primarily for internal use by controllers.
message ControllerRevision {
  // Standard object's metadata.
  // More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata
  // +optional

    neverInjectSelector: []
    alwaysInjectSelector: []
    # injectedAnnotations are additional annotations that will be added to the pod spec after injection
    # This is primarily to support PSP annotations. For example, if you defined a PSP with the annotations:
    #
    # annotations:
    #   apparmor.security.beta.kubernetes.io/allowedProfileNames: runtime/default

// the DaemonSet and StatefulSet controllers for update and rollback, this object is beta. However,
// it may be subject to name and representation changes in future releases, and clients should not
// depend on its stability. It is primarily for internal use by controllers.
message ControllerRevision {
  // Standard object's metadata.
  // More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata
  // +optional

# Istio operator code overview

## Introduction

This document covers primarily the code, with some background on how the design maps to it.
See the
[design doc](https://docs.google.com/document/d/11j9ZtYWNWnxQYnZy8ayZav1FMwTH6F6z6fkDYZ7V298/edit#heading=h.qex63c29z2to)
for a more complete design description. The operator code is divided roughly into five areas:

1. [IstioOperatorSpec API](#istiooperatorspec-api) and related infrastructure, which is expressed as a

// the DaemonSet and StatefulSet controllers for update and rollback, this object is beta. However,
// it may be subject to name and representation changes in future releases, and clients should not
// depend on its stability. It is primarily for internal use by controllers.
message ControllerRevision {
  // Standard object's metadata.
  // More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata
  // +optional