To work around this, Istio has a variety of abstractions meant to make writing controllers easier.

## Clients

Istio offers a variety of increasingly high level abstractions on top of the common Kubernetes [`client-go`](https://github.com/kubernetes/client-go).

```mermaid
flowchart TD
    kcg["Kubernetes client-go"]
    ic["Istio kube.Client"]
    ikc["Istio kclient.Client"]

set -e

UPDATE_BRANCH=${UPDATE_BRANCH:-"master"}

SCRIPTPATH="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
ROOTDIR=$(dirname "${SCRIPTPATH}")
cd "${ROOTDIR}"

# Get the sha of top commit
# $1 = repo
function getSha() {
  local dir result
  dir=$(mktemp -d)
  git clone --depth=1 "https://github.com/istio/${1}.git" -b "${UPDATE_BRANCH}" "${dir}"

  result="$(cd "${dir}" && git rev-parse HEAD)"

    install.operator.istio.io/owning-resource: {{ .Values.ownerName | default "unknown" }}
    operator.istio.io/component: "Pilot"
    release: {{ .Release.Name }}
data:
{{/* Scope the values to just top level fields used in the template, to reduce the size. */}}
  values: |-
{{ $vals := pick .Values "global" "istio_cni" "sidecarInjectorWebhook" "revision" -}}
{{ $pilotVals := pick .Values.pilot "cni" -}}

1. [Controller](#k8s-controller) code. The code comprises the K8s listener, webhook and logic for reconciling the cluster
to an `IstioOperatorSpec` CR.
1. [Manifest creation](#manifest-creation) code. User settings are overlaid on top of the
selected profile values and passed to a renderer in the Helm library to create manifests. Further customization on the
created manifests can be done through overlays.