Fix timeout for traefik-proxy source

[k8r-io]

Traefik 3.0 removes the legacy API group traefik.containo.us and earlier versions may be installed without the legacy API group setup.

This PR adds two flags, one to disable the legacy API group and one to disable the new API group. The default behavior of the traefik-proxy source is not changed.

Fixes #4075

Checklist

• Unit tests updated
• End user documentation updated

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: k8r-io / name: Kristopher Kirkland (9015377, 21398ec, f80f006, 9f29220)

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[k8r-io]

/easycla

[k8r-io]

/check-cla

[mloiseleur]

@k8r-io See this page for fixing cla.

[mloiseleur]

Thanks for this PR, @k8r-io
FTM, Traefik Proxy does not start without both API Group.
I'm not a big fan of this dual switch approach, but I also have to admit I don't have better idea :).
/ok-to-test

[mloiseleur]

The code looks good.
Since it's only for Traefik Proxy source, wdyt about adding a sentence or two about it in Traefik Source documentation ?

[k8r-io]

The code looks good. Since it's only for Traefik Proxy source, wdyt about adding a sentence or two about it in Traefik Source documentation ?

I was having trouble finding the right place to add the docs, I had forgotten about the tutorials directory.

Documentation has been added to a new section of the traefik-proxy.md so when older version of Traefik fall off external-dns's support matrix this section can be easily excised.

I agree that the approach with the flags is not great, or really good even. But it keeps default behavior the same and is also structured for easy removal later.

[mloiseleur]

/lgtm

[Raffo]

@k8r-io before I go on approving this.. Would you be able to provide into on when we will be able to remove those flags in the future? I'm worried that if we don't set a date we will keep those around for a very long time as I surely don't follow the traefik development.

[k8r-io]

@k8r-io before I go on approving this.. Would you be able to provide into on when we will be able to remove those flags in the future? I'm worried that if we don't set a date we will keep those around for a very long time as I surely don't follow the traefik development.

The new API group was added in Traefik 2.10 (https://github.com/traefik/traefik/blob/master/CHANGELOG.md#v2100-2023-04-24). So I believe we'd need the flags at least until external-dns drops off support for versions of Traefik older than that.

[Raffo]

/approve

@mloiseleur I'm pretty sure you have in mind the release cadence of traefik better than I do, let's chat in the near future on when we can drop the support mentioned here to clean things up.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Raffo

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