Update readme and diagrams

Signed-off-by: Stefan Prodan <[email protected]>

Author: stefanprodan

README.md

@@ -14,44 +14,37 @@ GitOps is a way to do Continuous Delivery, it works by using Git as a source of
 for declarative infrastructure and workloads.
 For Kubernetes this means using `git push` instead of `kubectl apply/delete` or `helm install/upgrade`.
 
-In this workshop you'll be using GitHub to host the config repository and [Flux](https://fluxcd.io) as the GitOps delivery solution.
+In this workshop you'll be using GitHub to host the config repository and [Flux](https://fluxcd.io)
+as the GitOps delivery solution.
 
 ### What is Progressive Delivery?
 
 Progressive delivery is an umbrella term for advanced deployment patterns like canaries, feature flags and A/B testing.
 Progressive delivery techniques are used to reduce the risk of introducing a new software version in production
 by giving app developers and SRE teams a fine-grained control over the blast radius.
 
-In this workshop you'll be using [Flagger](https://flagger.app) and Prometheus to automate Canary Releases and A/B Testing for your applications.
+In this workshop you'll be using [Flagger](https://flagger.app), Istio and Prometheus to automate
+Canary Releases and A/B Testing for your applications.
 
-![Progressive Delivery GitOps Pipeline](https://raw.githubusercontent.com/fluxcd/flagger/main/docs/diagrams/flagger-gitops-istio.png)
+![Progressive Delivery GitOps Pipeline](/docs/images/flux-flagger-gitops.png)
 
 ## Prerequisites
 
-You'll need a Kubernetes cluster **v1.16** or newer with `LoadBalancer` support. 
+You'll need a Kubernetes cluster **v1.20** or newer with `LoadBalancer` support. 
 For testing purposes you can use Minikube with 2 CPUs and 4GB of memory. 
 
-Install the `flux` CLI with Homebrew:
+Install `jq`, `yq` and the `flux` CLI with Homebrew:
 
 ```bash
-brew install fluxcd/tap/flux
+brew install jq yq fluxcd/tap/flux
 ```
 
-Binaries for macOS AMD64/ARM64, Linux AMD64/ARM and Windows are available
-to download on the [flux2 release page](https://github.com/fluxcd/flux2/releases).
-
 Verify that your cluster satisfies the prerequisites with:
 
 ```bash
 flux check --pre
 ```
 
-Install `jq` and `yq` with Homebrew:
-
-```bash
-brew install jq yq
-```
-
 Fork this repository and clone it:
 
 ```bash
@@ -86,7 +79,7 @@ check _Allow write access_, paste the Flux public key and click _Add key_.
 
 When Flux has access to your repository it will do the following:
 
-* installs the Istio operator
+* installs Istio using the Istio `base`, `istiod` and `gateway` Helm charts
 * waits for Istio control plane to be ready
 * installs Flagger, Prometheus and Grafana
 * creates the Istio public gateway
@@ -95,8 +88,9 @@ When Flux has access to your repository it will do the following:
 * creates the frontend deployment and canary
 * creates the backend deployment and canary
 
-When bootstrapping a cluster with Istio, it is important to define the apply order. For the applications
-pods to be injected with Istio sidecar, the Istio control plane must be up and running before the apps.
+When bootstrapping a cluster with Istio, it is important to control the installation order.
+For the applications pods to be injected with Istio sidecar,
+the Istio control plane must be up and running before the apps.
 
 With Flux v2 you can specify the execution order by defining dependencies between objects.
 For example, in [clusters/my-cluster/apps.yaml](https://github.com/stefanprodan/gitops-istio/blob/main/clusters/my-cluster/apps.yaml)
@@ -130,37 +124,48 @@ You can tail the Flux reconciliation logs with:
 flux logs --all-namespaces --follow --tail=10
 ```
 
-## Istio customizations and upgrades
+List all the Kubernetes resources managed by Flux with:
 
-![Flux Istio Operator](https://raw.githubusercontent.com/fluxcd/helm-operator-get-started/master/diagrams/flux-istio-operator.png)
+```bash
+flux tree kustomization flux-system
+```
+
+## Istio customizations
 
-You can customize the Istio installation with the `IstioOperator` resource located at
-[istio/system/profile.yaml](https://github.com/stefanprodan/gitops-istio/blob/main/istio/system/profile.yaml):
+You can customize the Istio installation using the Flux `HelmReleases` located at
+[istio/system/istio.yaml](https://github.com/stefanprodan/gitops-istio/blob/main/istio/system/istio.yaml):
 
 ```yaml
-apiVersion: install.istio.io/v1alpha1
-kind: IstioOperator
+apiVersion: helm.toolkit.fluxcd.io/v2beta1
+kind: HelmRelease
 metadata:
-  name: istio-default
+  name: istiod
   namespace: istio-system
 spec:
-  profile: demo
-  components:
+  # chart spec omitted 
+  values:
     pilot:
-      k8s:
-        resources:
-          requests:
-            cpu: 10m
-            memory: 100Mi
+      resources:
+        requests:
+          cpu: 100m
+          memory: 128Mi
 ```
 
-After modifying the Istio settings, you can push the change to git and Flux will apply it on the cluster. 
-The Istio operator will reconfigure the Istio control plane according to your changes.
+After modifying the Helm release values, you can push the change to git and Flux
+will reconfigure the Istio control plane according to your changes.
+
+## Istio control plane upgrades
+
+Istio upgrades are automated using GitHub Actions and Flux.
+
+![Flux Istio Operator](docs/images/flux-istio-gitops.png)
 
-When a new Istio version is available, the [`update-istio` GitHub Action workflow](https://github.com/stefanprodan/gitops-istio/blob/main/.github/workflows/update-istio.yaml)
-will open a pull request with the manifest updates needed for upgrading Istio Operator.
-The new Istio version is tested on Kubernetes Kind by the [`e2e` workflow](https://github.com/stefanprodan/gitops-istio/blob/main/.github/workflows/e2e.yaml)
-and when the PR is merged into the main branch, Flux will upgrade Istio in-cluster.
+When a new Istio version is available, the
+[`update-istio` GitHub Action workflow](https://github.com/stefanprodan/gitops-istio/blob/main/.github/workflows/update-istio.yaml)
+will open a pull request with the manifest updates needed for upgrading Istio.
+The new Istio version is tested on Kubernetes Kind by the
+[`e2e` workflow](https://github.com/stefanprodan/gitops-istio/blob/main/.github/workflows/e2e.yaml)
+and when the PR is merged into the main branch, Flux will upgrade Istio on the production cluster.
 
 ## Application bootstrap