# 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.

The `Workload` aims to represent everything about a workload (generally a `Pod` or `WorkloadEntry`).
This includes things like its IP address, identity, metadata (name, namespace, app, version, etc), and whether it has a waypoint proxy associated.

The `Service` aims to represent everything about a service (generally a `Service` or `ServiceEntry`).
This includes things like its IP addresses, ports and an associated waypoint proxy if it has one.

### Authorization Type

// For a given StorageClass, this describes the available capacity in a
// particular topology segment.  This can be used when considering where to
// instantiate new PersistentVolumes.
//
// For example this can express things like:
// - StorageClass "standard" has "1234 GiB" available in "topology.kubernetes.io/zone=us-east1"
// - StorageClass "localssd" has "10 GiB" available in "kubernetes.io/hostname=knode-abc123"
//

// For a given StorageClass, this describes the available capacity in a
// particular topology segment.  This can be used when considering where to
// instantiate new PersistentVolumes.
//
// For example this can express things like:
// - StorageClass "standard" has "1234 GiB" available in "topology.kubernetes.io/zone=us-east1"
// - StorageClass "localssd" has "10 GiB" available in "kubernetes.io/hostname=knode-abc123"
//

// For a given StorageClass, this describes the available capacity in a
// particular topology segment.  This can be used when considering where to
// instantiate new PersistentVolumes.
//
// For example this can express things like:
// - StorageClass "standard" has "1234 GiB" available in "topology.kubernetes.io/zone=us-east1"
// - StorageClass "localssd" has "10 GiB" available in "kubernetes.io/hostname=knode-abc123"
//

message VolumeSource {
  // hostPath represents a pre-existing file or directory on the host
  // machine that is directly exposed to the container. This is generally
  // used for system agents or other privileged things that are allowed
  // to see the host machine. Most containers will NOT need this.
  // More info: https://kubernetes.io/docs/concepts/storage/volumes#hostpath
  // ---

Often, these handlers are adding something to the queue like `client.AddEventHandler(controllers.ObjectHandler(queue.AddObject))`.
Construction should NOT actually start running all of these things, do I/O, or block in anyway.

Running the controller actually starts processing things.
Normally, this just means running the queue.
All informers created by `kube.Client` are kept track in the client, and started in one go with `RunAndWait` in one centralized call.

- **Epic**. An epic represents a feature area for Istio as a whole. Epics are fairly broad in scope and are basically product-level things.
Each issue is ultimately part of an epic.

- **Milestone**. Each issue is assigned a milestone. This is 0.1, 0.2, ..., or 'Nebulous Future'. The milestone indicates when we
think the issue should get addressed.