Updating documentation for argocd high-availability configuration

General MR

Summary

Updating documentation for argocd architecture document after configuring, deploying and testing a highly-available configuration of ArgoCD.

constraints such as the argocd-dev-server were documented to reflect components of ArgoCD that do not support HA.

Testing

After configuring for HA, the cypress tests were run locally to replicate adding and syncing projects. These ran without errors.

Issues

Closes #1278 (closed)

BB Processes

Add labels for affected packages so that they are deployed in CI as well as a status label:

Be sure to assign to yourself:

Once it is ready for review switch the status and assign reviewers:

docs/understanding-bigbang/package-architecture/argocd.md

@@ -68,7 +68,15 @@ Argo CD is largely stateless, all data is persisted as Kubernetes objects, which
 
 ### High Availability
 
-Upstream provides methods and docs for deploying argocd in HA. However, a production HA deployment of argocd within Big Bang has not been fully vetted and may produce results that vary.
+Upstream provides methods and [documentation](https://argo-cd.readthedocs.io/en/stable/operator-manual/high_availability/#argocd-dex-server-argocd-redis) for deploying argocd in HA.
+
+Requirements:
+- HA installation will require at least three different nodes due to pod anti-affinity roles in the specs.
+- `controller.replicas` and the `ARGOCD_CONTROLLER_REPLICAS` controller environment variable must have matching values (see below).
+- ArgoCD is pre-configured with the understanding of only three total redis servers. The package deploys a master with 3 replicas by default.
+
+Caveats:
+- The argocd-dex-server uses an in-memory database, and two or more instances would have inconsistent data.
 
 The following is an example of how to modify the Big Bang values to accommodate a HA deployment.
 
@@ -77,11 +85,14 @@ addons:
   argocd:
     values:
       controller:
-        replicas: 2
+        replicas: 3
+        env:
+        - name: "ARGOCD_CONTROLLER_REPLICAS"
+          value: "3"
       server:
-        replicas: 2  
+        replicas: 3
       repoServer:
-        replicas: 2              
+        replicas: 3
 ```
 
 For additional information about an ArgoCD high availability deployment visit [ArgoCD High Availability](https://argo-cd.readthedocs.io/en/stable/operator-manual/installation/#high-availability)