[RFC-0012] Add command flux export source external

[dgunzy]

Part of: #5504
[RFC-0012] Add command flux export source external

@stefanprodan - I added this, one thing I am not sure about is there is no SecretRef so I am just returning nil
let me know if there is a better way to go about this.

~/OpenSource/flux/flux2-fork add-export-source-external ?1 ❯ ./bin/flux export source external --all -n decomposition                                                     ⎈ kind-flux-test
---
apiVersion: source.toolkit.fluxcd.io/v1
kind: ExternalArtifact
metadata:
  labels:
    app.kubernetes.io/managed-by: source-watcher
    source.extensions.fluxcd.io/generator: 4b83e39f-4032-4808-a66f-3adea8878a37
  name: podinfo-backend
  namespace: decomposition
spec:
  sourceRef:
    apiVersion: source.extensions.fluxcd.io/v1beta1
    kind: ArtifactGenerator
    name: app-gen
    namespace: decomposition
---
apiVersion: source.toolkit.fluxcd.io/v1
kind: ExternalArtifact
metadata:
  labels:
    app.kubernetes.io/managed-by: source-watcher
    source.extensions.fluxcd.io/generator: 4b83e39f-4032-4808-a66f-3adea8878a37
  name: podinfo-cache
  namespace: decomposition
spec:
  sourceRef:
    apiVersion: source.extensions.fluxcd.io/v1beta1
    kind: ArtifactGenerator
    name: app-gen
    namespace: decomposition
---
apiVersion: source.toolkit.fluxcd.io/v1
kind: ExternalArtifact
metadata:
  labels:
    app.kubernetes.io/managed-by: source-watcher
    source.extensions.fluxcd.io/generator: 4b83e39f-4032-4808-a66f-3adea8878a37
  name: podinfo-frontend
  namespace: decomposition
spec:
  sourceRef:
    apiVersion: source.extensions.fluxcd.io/v1beta1
    kind: ArtifactGenerator
    name: app-gen
    namespace: decomposition

[matheuscscp]

The most interesting parts of an ExternalArtifact are in .status 🤔

[dgunzy]

@matheuscscp - updated to any

I agree, do you think I should change export to also export the status? It is a bit of a different pattern then I have seen elsewhere, but happy to do it!

[matheuscscp]

@matheuscscp - updated to any

I agree, do you think I should change export to also export the status? It is a bit of a different pattern then I have seen elsewhere, but happy to do it!

Maybe only for ExternalArtifact... @stefanprodan Thoughts?

[matheuscscp]

On a second thought, I'm not quite sure if exporting .status makes sense depending on the use cases of this command. I think flux export is supposed to be used for getting resources out of the cluster for checking them into Git, and .status is always managed by something else (e.g. a controller), and not by the Flux appliers, as they don't patch the status subresource of the applied objects.

One could also end up thinking: "Well, ExternalArtifact is automatically created by source-watcher as a result of reconciling ArtifactGenerator, so what's the point of exporting ExternalArtifact objects anyway?" And I guess the use case here lies in the .spec.sourceRef field. An external source controller could respond to an ExternalArtifact object with .spec.sourceRef.kind set to a kind that it manages by patching the status of this EA.

@stefanprodan I guess this is what we discussed before, right?

[stefanprodan]

The export functions shouldn't print the status. In the case of EA, export is useful when the generation and reconciliation is decoupled, e.g. there is a dedicated controller that watcher external artifacts and sets their status.

[stefanprodan]

@dgunzy could you please add tests for this.

[dgunzy]

@stefanprodan @matheuscscp - I added a test in export_test.go - if there is a good place to add some additional tests let me know!

[stefanprodan]

LGTM

Thanks @dgunzy