Notifications for Applications created by AppSource

[aceamarco]

Summary

We can utilize the pre-existing Notifications Engine to add a notifications field to the AppSource instance — so that Dev Teams can be notified about what is happening with their applications.

Motivation

Dev teams can stay informed about the state of their Applications through notifications.

Proposal

We add a optional notifications.channel field to the AppSource instance that will add an annotation to the Application within the Application Create Request made by the controller.

Here is an example AppSource instance manifest:

apiVersion: argoproj.io/v1alpha1
kind: AppSource
metadata:
  name: appsource-sample1
  namespace: my-project-us-west-2
spec:
  path: kustomize-guestbook
 # New Field
  notifications.channel: my_channel
  repoURL: https://github.com/argoproj/argocd-example-apps

This is the Application it would create:

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  annotations:
    # New annotation
    notifications.argoproj.io/subscribe.on-sync-succeeded.slack: my_channel
. . .