[mopsos-notifications] initial helm chart

[hairmare]

It would be nice to have a mopsos-notifications Helm chart that installs the needed notification templates and secrets needed for sending CloudEvents from Argo CD notifications.

We need to check if/how argocd-notifications supports this first tho. If it doesn't, then we could have the mopsos-notifications chart schedule a job that uses some very simple kubectl --patch magic to get the job done.

[hairmare]

Currently Argo CD notifications supports configuring notifications in a single configmap specified by the config-map-name flag (default: argocd-notifications-cm).

If we want to have different charts manage different bits of the configmap, then we would probably have to raise an issue with upstream, asking them to support discovering templates in multiple configmaps via labels selectors.

As a workaround we can configure them globally for now, or to solve this issue we can do a hacky kubectl patch job.

https://github.com/argoproj/argo-cd/blob/0ff1ada720ca83d764683b7930a62e726dfab87b/cmd/argocd-notification/commands/controller.go#L133

[tongpu]

This would be interesting to raise upstream, as I'm going to face similar pains in the future with regards to policy.csv also being in a single ConfigMap.

[hairmare]

i'll report back once i raised the notifications issue with upstream, the policy.csv is probably a different one tho.