Add common labels for components

[artem-nefedov]

It's great that Flux manifests are now uploaded to OCI registries, and therefore can be installed with Kustomize controller.
However, one thing that's not convenient to do is disabling certain components.
A potentially good solution here is to add component-based labels (or annotations) to all resources.

For example, if all resources related to image-reflector-controller (Deployment, Service, CRD, etc.) would have a label kind: image-reflector-controller, then I could use a following Kustomization to deploy flux while disabling all image-reflector-controller components:

apiVersion: kustomize.toolkit.fluxcd.io/v1beta2
kind: Kustomization
metadata:
  name: flux
  namespace: flux-system
spec:
  interval: 1m0s
  path: ./flux-system
  prune: false
  patches:
  - target:
      labelSelector: kind=image-reflector-controller
    patch: |
      $patch: delete
      kind: ignored
      apiVersion: ignored
      metadata:
        name: ignored
  sourceRef:
    kind: OCIRepository
    name: flux

[stefanprodan]

Besides source-controller all Flux components are optional e.g. flux bootstrap --components --components-extra.

[artem-nefedov]

My suggestion specifically relates to installing flux from publicly available OCI artifact.

[stefanprodan]

Why not scale those deployments to zero?

[artem-nefedov]

Not having to install unneeded components at all is much cleaner option in my opinion

[stefanprodan]

I would not add common labels as those alter the label selectors, instead let's use this https://github.com/fluxcd/flux2/blob/main/manifests/install/labels.yaml in all bases in here https://github.com/fluxcd/flux2/tree/main/manifests/bases. The label could be app.kubernetes.io/component. Please open a PR, thanks.

[stefanprodan]

I've added the app.kubernetes.io/component label to each controller's resources in #3145

You'll be able to opt-out from installing specific controllers using a label selector stating with Flux v0.35.0.