# Istio CNI Node Agent

The Istio CNI Node Agent is responsible for several things

- Install an Istio CNI plugin binary on each node's filesystem, updating that node's CNI config in e.g (`/etc/cni/net.d`), and watching the config and binary paths to reinstall if things are modified.

LINUX_AGENT_BINARIES:=./cni/cmd/istio-cni \
  ./cni/cmd/install-cni \
  $(AGENT_BINARIES)

BINARIES:=$(STANDARD_BINARIES) $(AGENT_BINARIES) $(LINUX_AGENT_BINARIES)

# List of binaries that have their size tested
RELEASE_SIZE_TEST_BINARIES:=pilot-discovery pilot-agent istioctl envoy ztunnel client server

	"istio.io/istio/pkg/monitoring"
)

var (
	eventTypeTag = monitoring.CreateLabel("type")
	EventTotals  = monitoring.NewSum(
		"nodeagent_reconcile_events_total",
		"The total number of node agent reconcile events.",
	)
)

type K8sHandlers interface {
	GetPodIfAmbient(podName, podNamespace string) (*corev1.Pod, error)
	GetAmbientPods() []*corev1.Pod
	Start()
}

type InformerHandlers struct {

			cniClient := newCNIClient(conf.CNIEventAddress, constants.CNIAddEventPath)
			if err = PushCNIEvent(cniClient, args, prevResIps, podName, podNamespace); err != nil {
				log.Errorf("istio-cni cmdAdd failed to signal node Istio CNI agent: %s", err)
				return err
			}
			return nil
		}
		log.Debugf("istio-cni ambient cmdAdd podName: %s - not ambient enabled, ignoring", podName)
	}
	// End ambient plugin logic

	pi := &PodInfo{}

		if cfg.InstallConfig.AmbientEnabled {
			// Start ambient controller

			// node agent will spawn a goroutine and watch the K8S API for events,
			// as well as listen for messages from the CNI binary.
			log.Info("Starting ambient node agent with inpod redirect mode")
			ambientAgent, err := nodeagent.NewServer(ctx, watchServerReady, cfg.InstallConfig.CNIEventAddress,
				nodeagent.AmbientArgs{

            type: DirectoryOrCreate # DirectoryOrCreate instead of Directory for the following reason - CNI may not bind mount this until a non-hostnetwork pod is scheduled on the node,
            # and we don't want to block CNI agent pod creation on waiting for the first non-hostnetwork pod.