## Proxy implementation

In its initial implementations, the ztunnel was actually implemented in 3 different ways: a bespoke Rust implementation, a bespoke Go implementation, and in Envoy.

In the end, [after evaluation](https://docs.google.com/document/d/1c2123cKuYsBDpIon9FFdctWTUIMFweSjgwG7r8l3818/edit), the decision was to move forward with a Rust implementation.

        * Is this turned on by default?
        * How many users are affected by this change?

## Feature implementation

Release managers will continue to have a final say in what gets merged or not, unless directed by the TOC. See the next
section if the implementation is done, but a bug is being addressed.

// that are required to describe the RuntimeClass to the Container Runtime
// Interface (CRI) implementation, as well as any other components that need to
// understand how the pod will be run. The RuntimeClassSpec is immutable.
message RuntimeClassSpec {
  // runtimeHandler specifies the underlying runtime and configuration that the
  // CRI implementation will use to handle pods of this class. The possible

For consistency, the same profiles are used across each chart, even if they do not impact a given chart.

Explicitly set values have highest priority, then profile settings, then chart defaults.

As an implementation detail of profiles, the default values for the chart are all nested under `defaults`.
When configuring the chart, you should not include this.

  // +optional
  optional k8s.io.apimachinery.pkg.apis.meta.v1.ObjectMeta metadata = 1;

  // handler specifies the underlying runtime and configuration that the CRI
  // implementation will use to handle pods of this class. The possible values
  // are specific to the node & CRI configuration.  It is assumed that all
  // handlers are available on every node, and handlers of the same name are

| HOST_PROBE_SNAT_IPV6 | "fd16:9254:7127:1337:ffff:ffff:ffff:ffff" | IPv6 link local ranges are designed to be collision-resistant by default, and so this probably never needs to be overridden |

## Sidecar Mode Implementation Details

Istio CNI injection is currently based on the same Pod annotations used in init-container/inject mode.

### Selection API

- plugin config "exclude namespaces" applies first
- ambient is enabled if:

# PeerAuthentication Implementation in Ambient

func NewSDSWriter(w io.Writer, format Format) SDSWriter {
	return &sdsWriter{
		w:      w,
		output: format,
	}
}

// sdsWriter is provided concrete implementation of SDSWriter
type sdsWriter struct {
	w      io.Writer
	output Format
}

// PrintSecretItems uses the user supplied output format to determine how to display the diffed secrets

  // +optional
  optional k8s.io.apimachinery.pkg.apis.meta.v1.ObjectMeta metadata = 1;

  // handler specifies the underlying runtime and configuration that the CRI
  // implementation will use to handle pods of this class. The possible values
  // are specific to the node & CRI configuration.  It is assumed that all
  // handlers are available on every node, and handlers of the same name are

For consistency, the same profiles are used across each chart, even if they do not impact a given chart.

Explicitly set values have highest priority, then profile settings, then chart defaults.

As an implementation detail of profiles, the default values for the chart are all nested under `defaults`.
When configuring the chart, you should not include this.
That is, `--set some.field=true` should be passed, not `--set defaults.some.field=true`.