message DaemonSetSpec {
  // A label query over pods that are managed by the daemon set.
  // Must match in order to be controlled.
  // It must match the pod template's labels.
  // More info: https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#label-selectors
  optional k8s.io.apimachinery.pkg.apis.meta.v1.LabelSelector selector = 1;

  // An object that describes the pod that will be created.

  // items is a list of schema objects.
  repeated RuntimeClass items = 2;
}

// Scheduling specifies the scheduling constraints for nodes supporting a
// RuntimeClass.
message Scheduling {
  // nodeSelector lists labels that must be present on nodes that support this
  // RuntimeClass. Pods using this RuntimeClass can only be scheduled to a
  // node matched by this selector. The RuntimeClass nodeSelector is merged

- `istio-iptables`
    - sets up iptables to redirect a list of ports to the port envoy will listen
    - shared code with istio-init container
    - it will generate an iptables-save config, based on annotations/labels and other settings, and apply it.

### CmdAdd Sidecar Workflow

`CmdAdd` is triggered when there is a new pod created. This runs on the node, in a chain of CNI plugins - Istio is

  // for more examples of label selectors.
  //
  // Default to the empty LabelSelector, which matches everything.
  // +optional
  optional k8s.io.apimachinery.pkg.apis.meta.v1.LabelSelector namespaceSelector = 5;

  // ObjectSelector decides whether to run the webhook based on if the
  // object has matching labels. objectSelector is evaluated against both

  // +optional
  optional k8s.io.apimachinery.pkg.apis.meta.v1.LabelSelector selector = 4;

  // manualSelector controls generation of pod labels and pod selectors.
  // Leave `manualSelector` unset unless you are certain what you are doing.
  // When false or unset, the system pick labels unique to this job
  // and appends those labels to the pod template.  When true,

  // topology contains arbitrary topology information associated with the
  // endpoint. These key/value pairs must conform with the label format.
  // https://kubernetes.io/docs/concepts/overview/working-with-objects/labels
  // Topology may include a maximum of 16 key/value pairs. This includes, but
  // is not limited to the following well known keys:
  // * kubernetes.io/hostname: the value indicates the hostname of the node

  // * Exact: Matches the URL path exactly.
  // * Prefix: Matches based on a URL path prefix split by '/'. Matching is
  //   done on a path element by element basis. A path element refers is the
  //   list of labels in the path split by the '/' separator. A request is a
  //   match for path p if every p is an element-wise prefix of p of the
  //   request path. Note that if the last element of the path is a substring

  // When a driver is initialized on a node, it provides the same topology keys
  // along with values. Kubelet will expose these topology keys as labels
  // on its own node object.
  // When Kubernetes does topology aware provisioning, it can use this list to
  // determine which labels it should retrieve from the node object and pass
  // back to the driver.
  // It is possible for different nodes to use different topology keys.

### Inbound

Traffic entering a pod over HBONE will be handled by the "inbound" code path, on port 15008.

Incoming requests have multiple "layers": TLS wrapping HTTP CONNECT that is wrapping the user's connection.

To unwrap the first layer, we terminate TLS.
As part of this, we need to pick the correct certificate to serve on behalf of the destination workload.

  // for more examples of label selectors.
  //
  // Default to the empty LabelSelector, which matches everything.
  // +optional
  optional k8s.io.apimachinery.pkg.apis.meta.v1.LabelSelector namespaceSelector = 5;

  // ObjectSelector decides whether to run the webhook based on if the
  // object has matching labels. objectSelector is evaluated against both