From c11c172b5de8c8b565dc65957d117a659e01977a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Blaise?=
 <32685572+clementblaise@users.noreply.github.com>
Date: Wed, 29 Nov 2023 17:39:28 -0500
Subject: [PATCH] Argo CD Improvements (#630)

---
 .../integrations/argo-cd-crossplane.md        | 59 ++++++++++++++++---
 1 file changed, 51 insertions(+), 8 deletions(-)

diff --git a/content/knowledge-base/integrations/argo-cd-crossplane.md b/content/knowledge-base/integrations/argo-cd-crossplane.md
index 86d673a1..4b2c737f 100644
--- a/content/knowledge-base/integrations/argo-cd-crossplane.md
+++ b/content/knowledge-base/integrations/argo-cd-crossplane.md
@@ -8,23 +8,38 @@ are a great combination. Argo CD provides GitOps while Crossplane turns any Kube
 cluster into a Universal Control Plane for all of your resources. There are
 configuration details required in order for the two to work together properly.
 This doc will help you understand these requirements. It is recommended to use
-
 Argo CD version 2.4.8 or later with Crossplane.
  
 Argo CD synchronizes Kubernetes resource manifests stored in a Git repository
 with those running in a Kubernetes cluster (GitOps). There are different ways to configure 
-
 how Argo CD tracks resources. With Crossplane, you need to configure Argo CD 
 to use Annotation based resource tracking. See the [Argo CD docs](https://argo-cd.readthedocs.io/en/latest/user-guide/resource_tracking/) for additional detail.
  
 ### Configuring Argo CD with Crossplane
- 
-To configure Argo CD for Annotation resource tracking and Health Status, edit the `argocd-cm`
 
-`ConfigMap` in the `argocd` `Namespace`. Add `application.resourceTrackingMethod: annotation`
+#### Set Resource Tracking Method
 
-to the data section as below:
+In oder for Argo CD to correctly track an Application resources that contain Crossplane related object it needs
+to be configured to use the annotation mechanism.
 
+To configure it, edit the `argocd-cm` `ConfigMap` in the `argocd` `Namespace` as such:
+```yaml
+apiVersion: v1
+kind: ConfigMap
+data:
+  application.resourceTrackingMethod: annotation
+```
+
+#### Set Health Status
+
+Argo CD has a built-in health assessment for Kubernetes resources. Some checks are supported by the community directly
+in Argo's [repository](https://github.com/argoproj/argo-cd/tree/master/resource_customizations). For example the `Provider`
+from `pkg.crossplane.io` has already been declared which means there no further configuration needed.
+
+Argo CD also enable customising these checks per instance, and that's the mechanism used to provide support
+of Provider's CRDs
+
+To configure it, edit the `argocd-cm` `ConfigMap` in the `argocd` `Namespace` as such:
 ```yaml
 apiVersion: v1
 kind: ConfigMap
@@ -110,8 +125,36 @@ data:
         return health_status
 ```
 
-On the next Argo CD sync, Crossplane `Claims` and `Composite Resources` will
+#### Set Resource Exclusion
 
-be considered synchronized with status and will not trigger auto-pruning.
+Crossplane providers generates a `ProviderConfigUsage` for each of the managed resource (MR) it handles. This resource
+enable representing the relationship between MR and a ProviderConfig so that controller can use it as finalizer when a
+ProviderConfig is deleted. End-user of Crossplane are not expected to interact with this resource.
+
+Argo CD UI reactivity can be impacted as the number of resource and types grow. To help keep this number low we
+recommend hiding all `ProviderConfigUsage` resources from Argo CD UI.
+
+To configure resource exclusion  edit the `argocd-cm` `ConfigMap` in the `argocd` `Namespace` as such:
+```yaml
+apiVersion: v1
+kind: ConfigMap
+data:
+    resource.exclusions: |
+      - apiGroups:
+        - "*"
+        kinds:
+        - ProviderConfigUsage
+```
+
+The use of `"*"` as apiGroups will enable the mechanism for all Crossplane Providers.
+
+#### Increase K8s Client QPS
+
+As the number of CRDs grow on a control plane it will increase the amount of queries Argo CD Application Controller
+needs to send to the Kubernetes API. If this is the case you can increase the rate limits of the Argo CD Kubernetes client.
 
 Set the environment variable `ARGOCD_K8S_CLIENT_QPS` to `300` for improved compatibility with a large number of CRDs.
+
+The default value of `ARGOCD_K8S_CLIENT_QPS` is 50, modifying the value will also update `ARGOCD_K8S_CLIENT_BURST` as it
+is default to `ARGOCD_K8S_CLIENT_QPS` x 2.
+