# Architecture of Istiod

This document describes the high level architecture of the Istio control plane, Istiod.
Istiod is structured as a modular monolith, housing a wide range of functionality from certificate signing, proxy configuration (XDS), traditional Kubernetes controllers, and more.

## Proxy Configuration

And even if you were not using FastAPI, you could also write your own async applications with <a href="https://anyio.readthedocs.io/en/stable/" class="external-link" target="_blank">AnyIO</a> to be highly compatible and get its benefits (e.g. *structured concurrency*).

### Other forms of asynchronous code

This style of using `async` and `await` is relatively new in the language.

But it makes working with asynchronous code a lot easier.

[default profile](../manifests/profiles/default.yaml) is used. Each profile is defined as a
set of defaults for `IstioOperatorSpec`, for both the restructured fields (K8s settings, namespaces and enablement)
and the Helm values (Istio behavior configuration).

1. The fields defined in the user CR override any values defined in the configuration profile CR.  The

```

Here are the steps to resolve the issue:

1. Open the failure report mentioned in the output.\
If you don't see the report link in the output in the IDE, make sure to select the top-level node in the structured output panel.
The report will explain the errors in detail.
Perhaps, you forgot to add an `@Incubating` annotation or `@since` in the javadoc.

2. Accept the changes.\

defines install time parameters like component and enablement and namespace, and K8s settings like resources, HPA spec etc. in a structured way.
The simplest customization is to turn components on and off. For example, to turn on cni ([samples/cni-on.yaml](samples/cni-on.yaml):

```yaml
apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
spec: