Add an example to demonstrate application deployments using ArgoCD

[devdattakulkarni]

GitOps tools such as ArgoCD perform app deployments. KubePlus also performs app deployments. How do these two systems work together?

It will be good to have an example showcasing how KubePlus and a GitOps system like ArgoCD work together.

[devdattakulkarni]

Conceptually, this will work as follows:

ArgoCD and KubePlus will need to be installed on the cluster.

In KubePlus we will create an Application Kind (Say - HelloWorld). Then we use ArgoCD to manage instances of HelloWorld.
When a HelloWorld YAML is created and pushed to the application repository, ArgoCD will pick it up and apply it to the cluster. This will trigger KubePlus, which will perform creation of the HelloWorld Pod. When the HelloWorld YAML is updated and pushed to the app repo, ArgoCD will pick it up and apply to the cluster. This should trigger an update operation in KubePlus.

Say, at the beginning, HelloWorld YAML has a spec field "replicas" set to 1. When the YAML is created and pushed to the app repo, an instance of hello-world should be created with 1 Pod. When the spec field "replicas" is updated to 2, and pushed to the app repo, the instance of hello-world should be updated to 2 Pods.

Above setup assumes that ArgoCD is configured to watch and deploy Application Kinds. If on the other hand, ArgoCD is configured to directly deploy Helm charts (using helm install), then we will need to retrofit the Helm release with multi-instance multi-tenancy policies (See #1447)

[devdattakulkarni]

@PatrickBladeeman Thanks!