#### CRD Watcher

For watches against custom types (CRDs), we want to gracefully handle missing CRDs. Naively starting informers against the missing types would result in errors and blocking startup. Instead, we introduce a "CRD Watcher" component that watches the CRDs in the cluster to determine if they are available or not.

	n := match.GetMatcherTree().GetInput().GetName()

	var m map[string]*matcher.Matcher_OnMatch
	equality := "="
	switch v := match.GetMatcherTree().GetTreeType().(type) {
	case *matcher.Matcher_MatcherTree_ExactMatchMap:
		m = v.ExactMatchMap.Map
	case *matcher.Matcher_MatcherTree_PrefixMatchMap:
		m = v.PrefixMatchMap.Map
		equality = "^"
	case *matcher.Matcher_MatcherTree_CustomMatch:
		tc := v.CustomMatch.GetTypedConfig()

Xiaopeng Han <******@****.***> 1709887099 +0800

- watches k8s resource for existing pods, so that pods that have already been started can be moved in or out of the ambient mesh.
- sends UDS events to ztunnel via a socket whenever a pod is enabled for ambient mesh (whether from CNI plugin or node watcher), instructing ztunnel to create the "tube" socket.

	logLevel string
}

type scopeStackTraceLevelPair ScopeLevelPair

func newScopeLevelPair(slp, validationPattern string) (*ScopeLevelPair, error) {
	matched, err := regexp.MatchString(validationPattern, slp)
	if err != nil {
		return nil, err
	}
	if !matched {
		return nil, fmt.Errorf("pattern %s did not match", slp)
	}
	scopeLogLevel := strings.Split(slp, ":")
	s := &ScopeLevelPair{
		scope:    scopeLogLevel[0],

  // matches only a single label. You cannot have a wildcard label by itself (e.g. Host == "*").
  // Requests will be matched against the Host field in the following way:
  // 1. If host is precise, the request matches this rule if the http host header is equal to Host.
  // 2. If host is a wildcard, then the request matches this rule if the http host header

```yaml
apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
spec:
  components:
    pilot:
      k8s:
        overlays:
        - kind: Deployment
          name: istio-pilot
          patches:
          - path: spec.template.spec.containers.[name:discovery].args.[30m]
            value: "60m" # OVERRIDDEN
          - path: spec.template.spec.containers.[name:discovery].ports.[containerPort:8080].containerPort

}

var interceptorFunc = interceptor.Funcs{Patch: func(
	ctx context.Context,
	clnt client.WithWatch,
	obj client.Object,
	patch client.Patch,
	opts ...client.PatchOption,
) error {
	// Apply patches are supposed to upsert, but fake client fails if the object doesn't exist,
	// if an apply patch occurs for an object that doesn't yet exist, create it.
	if patch.Type() != types.ApplyPatchType {

		if len(filename) == 0 {
			filename = "YYY-istio-cni.conf"
		}
		return filepath.Join(cfg.mountedCNINetDir, filename), nil
	}

	watcher, err := util.CreateFileWatcher(cfg.mountedCNINetDir)
	if err != nil {
		return "", err
	}
	defer watcher.Close()

	for len(filename) == 0 {
		filename, err = getDefaultCNINetwork(cfg.mountedCNINetDir)
		if err == nil {
			break
		}

  // MatchConditions is a list of conditions that must be met for a request to be sent to this
  // webhook. Match conditions filter requests that have already been matched by the rules,
  // namespaceSelector, and objectSelector. An empty list of matchConditions matches all requests.
  // There are a maximum of 64 match conditions allowed.
  //
  // The exact matching logic is (in order):