* The Kubernetes Service Discovery controller is a bit of a monolith, and spins off a bunch of other sub-controllers in addition to the core service discovery controller.

Because of the monolithic complexity it helps to see this magnified a bit:

```mermaid
graph BT
    mcsc("Multicluster Secret")
    scr("Credentials Controller")
    ksd("Kubernetes Service Controller")
    nsc("Namespace Controller")

Istio Version:       1.21.0-1226
Istio Proxy Version: ee85c5f28702f00621aed895915fca565796b9e4
Envoy Version:       0.0.0

NAME                                                                SERVICE FQDN                          PORT     SUBSET     DIRECTION       TYPE       DESTINATION RULE
cluster/agent                                                       cluster/agent                         -        -          -               STATIC     

// IngressBackend describes all endpoints for a given service and port.
message IngressBackend {
  // service references a service as a backend.
  // This is a mutually exclusive setting with "Resource".
  // +optional
  optional IngressServiceBackend service = 4;

  // resource is an ObjectRef to another Kubernetes resource in the namespace
  // of the Ingress object. If resource is specified, a service.Name and

This includes things like its IP address, identity, metadata (name, namespace, app, version, etc), and whether it has a waypoint proxy associated.

The `Service` aims to represent everything about a service (generally a `Service` or `ServiceEntry`).
This includes things like its IP addresses, ports and an associated waypoint proxy if it has one.

### Authorization Type

#### DNS SRV Records

Many Active Directory and other LDAP services are setup with [DNS SRV Records](https://ldap.com/dns-srv-records-for-ldap/) for high-availability of the directory service. To use this to find LDAP servers to connect to, an LDAP client makes a DNS SRV record request to the DNS service on a domain that looks like `_service._proto.example.com`. For LDAP the `proto` value is always `tcp`, and `service` is usually `ldap` or `ldaps`.

  // Un-prefixed names are reserved for IANA standard service names (as per
  // RFC-6335 and https://www.iana.org/assignments/service-names).
  // Non-standard protocols should use prefixed names such as
  // mycompany.com/my-custom-protocol.
  // +optional
  optional string appProtocol = 4;
}

// EndpointSlice represents a subset of the endpoints that implement a service.

// +structType=atomic
message EndpointPort {
  // name represents the name of this port. All ports in an EndpointSlice must have a unique name.
  // If the EndpointSlice is dervied from a Kubernetes service, this corresponds to the Service.ports[].name.
  // Name must either be an empty string or pass DNS_LABEL validation:
  // * must be no more than 63 characters long.
  // * must consist of lower case alphanumeric characters or '-'.

</a>

---

Istio is an open source service mesh that layers transparently onto existing distributed applications. Istio’s powerful features provide a uniform and more efficient way to secure, connect, and monitor services. Istio is the path to load balancing, service-to-service authentication, and monitoring – with few or no service code changes.

  // +optional
  optional string clusterIP = 3;

  // ClusterIPs is a list of IP addresses assigned to this service, and are
  // usually assigned randomly.  If an address is specified manually, is
  // in-range (as per system configuration), and is not in use, it will be
  // allocated to the service; otherwise creation of the service will fail.

  // allowed, either.
  //
  // +optional
  optional string url = 3;

  // `service` is a reference to the service for this webhook. Either
  // `service` or `url` must be specified.
  //
  // If the webhook is running within the cluster, then you should use `service`.
  //
  // +optional
  optional ServiceReference service = 1;