## Features requiring API changes

If a PR change requires an API change
* Updates to documentation do not require explicit approval from the Technical Oversight Committee (TOC). This can be
  held off after the release. Hiding/Showing documentation does not require TOC approval.
* Cases for other API changes require TOC approval

    CZ--"HBONE (actual)"-->SZ
    SZ--Plain-->Server
```

### Pooling

User connections can be multiplexed over shared HBONE connections.
This is done through standard HTTP/2 pooling.
The pooling is keyed off the `{source identity, destination identity, destination ip}`.

### Headers

Ztunnel uses the following well-known headers in HBONE:

defines install time parameters like component and enablement and namespace, and K8s settings like resources, HPA spec etc. in a structured way.
The simplest customization is to turn components on and off. For example, to turn on cni ([samples/cni-on.yaml](samples/cni-on.yaml):

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

not impact the `Cluster` type, so we can skip generating `Cluster` in this case. Warning: Envoy currently has a bug that *requires* `Endpoints` to be pushed any time the corresponding `Cluster` is pushed, so this optimization is intentionally turned off in this specific case.

Finally, we determine which subset of the type we need to generate. XDS has two modes - "State of the World (SotW)" and "Delta". In SotW, we generally need to generate all resources of the type, even if only one changed....