Enable commiting the changes made by controllers back to Git - Improve GitOps support

[thecooldrop]

Summary

As a developer in GitOps team I would like to be able to track my cluster state in my GitOps repository.

I would like the controllers to make the changes to my cluster either:

1. Indirectly by commiting the desired state back to my GitOps repository

Or

2. By commiting the state change back to my repository after making the changes in cluster.

Use Cases

An example use case would be management of blue-green deployment in declarative fashion. When I make a change to a rollout then the Service gets changed as well. Currently this is done by patching and leads to differences between state described in GitOps repository and the state actually deployed into cluster. Tools which perform automatic synchronization would detect this and thus would undo the changes made by controller.

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[kostis-codefresh]

I don't think that this should be a responsibility of Argo Rollouts. Argo Rollouts knows nothing about Git right now (and it shouldn't know IMHO)

Have you seen https://github.com/argoproj-labs/argocd-image-updater ?
One of its goals is to write back in Git as you describe (Again I think that ArgoCD is the project that should have this functionality and not Argo Rollouts).

[jessesuen]

Agree that this is outside the purview of Argo Rollouts. Argo CD Image Updater is an example of how this could be done as a separate project (but for changes to image registries and live objects). I think you should explore that as an option since git writeback isn't something that would likely ever be part of the controller.'

Second, the upcoming notification support will have support for webhook notifications that could be invoked upon RolloutUpdated events. You may be able to leverage argo rollout notifications to achieve your use case by calling a webhook of your own service, which could perform the git writeback.

[jessesuen]

See: #1175