### Controllers overview

Below provides a high level overview of controllers in Istiod. For more information about each controller, consulting the controllers Go docs is recommended.

```mermaid
graph BT
    crd("CRD Watcher")
    subgraph Service Discovery
        ksd("Kubernetes Controller")
        sesd("Service Entry Controller")
        msd("Memory Controller")
        asd("Aggregate")
        ksd--Join-->asd

package precheck

import (
	"context"
	"errors"
	"fmt"
	"strconv"
	"strings"

	"github.com/fatih/color"
	"github.com/spf13/cobra"
	authorizationapi "k8s.io/api/authorization/v1"
	crd "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
	kerrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"sigs.k8s.io/yaml"

	"istio.io/api/label"

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