catch pod creation events and notify the CNI agent early enough to set up network redirection before the pod is fully started. This is necessary because the CNI plugin is effectively the first thing to see a scheduled pod - before the K8S control plane will see things like the pod IP or networking info, the CNI will - but the CNI plugin alone is not sufficient to handle all pod events (already-started pod updates, rebuilding current state on CNI restart) that the node agent cares about.

##...

stable version in place and gradually migrate apps to the new version.

- More flexibility: the new installer allows multiple 'environments', allowing applications to select
a set of control plane settings and components. While the entire mesh respects the same APIs and config,
apps may target different 'environments' which contain different instances and variants of Istio.

three main components:

- [MeshConfig](https://github.com/istio/api/blob/master/mesh/v1alpha1/config.proto) for runtime config consumed directly by Istio
control plane components.
- [Component configuration API](https://github.com/istio/api/blob/00671adacbea20f941cb20cce021bc63cbad1840/operator/v1alpha1/operator.proto#L42-L93), for managing

```yaml
meshConfig:
  accessLogFile: /dev/stdout
```

#### Revisions

Control plane revisions allow deploying multiple versions of the control plane in the same cluster.
This allows safe [canary upgrades](https://istio.io/latest/docs/setup/upgrade/canary/)

```yaml
revision: my-revision-name

microservices](https://istio.io/latest/docs/examples/microservices-istio/), manage [traffic flow](https://istio.io/latest/docs/concepts/traffic-management/) across microservices, enforce policies
and aggregate telemetry data. Istio's control plane provides an abstraction
layer over the underlying cluster management platform, such as Kubernetes.

Istio is composed of these components:

- **Envoy** - Sidecar proxies per microservice to handle ingress/egress traffic