disable path overlap validation flag

[Fsero]

What this PR does / why we need it:

In #5651 there was a
request to throw an error when there are two ingresses defining the same
host and path, which was implemented as part of the validation webhook.

Despite of this there are clear rules on the ingress controller that
describes what the controller would do in such situation (the oldest
rule wins)

Some users are relying on this validation behaviour to prevent
misconfigurations, but there are use cases where allowing it, maybe
temporarily, is helpful. Those use cases includes:

• Splitting large ingresses objects in smaller ones Impossible to change hostname<->ingress mapping without downtime due to admission webhook #10820
• Moving ingress objects between namespaces without downtime (like when you transfer an ingress from team A that owns namespace A to team B that owns namespace B) Duplicate location in NGINX config when using both Prefix and Exact path types #10090

Types of changes

• Bug fix (non-breaking change which fixes an issue)

• New feature (non-breaking change which adds functionality)

• CVE Report (Scanner found CVE and adding report)

• Breaking change (fix or feature that would cause existing functionality to change)

• Documentation only

  Which issue/s this PR fixes

fixes #10820
fixes #10090

How Has This Been Tested?

building an image and testing it in a local cluster, will update later
with some real life scenarios

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have added unit and/or e2e tests to cover my changes.
• All new and existing tests passed.

Change-Id: I9d4124d1c36876b06d63100cd10988eaf2f41db9

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[longwuyuan]

From the K8S official resources, it will be useful to add a link here that covers the specs and KEP for any ingress-controller, to deal with duplicate routing rule factors like identical hostname and identical path.

[strongjz]

I'm not sure about adding footguns like this to the configuration.

With that said, we can add it but disable it as default, so the cluster admin has to choose to allow it consciously.

It may be in the check overlap function, but can you ensure this dumps out a warning in the admission logs?

Can you add an e2e test about this with it enabled and disabled?

[strongjz]

/kind feature

[strongjz]

/lgtm

/hold

ill let @rikatz take a look and then we can get it merged into main.

Probably going to into 1.11.0, trying not to add features in patch release.

[cpanato]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cpanato, Fsero, strongjz

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[k8s-ci-robot]

New changes are detected. LGTM label has been removed.

[Fsero]

@strongjz @cpanato @rikatz just rebased in top of main this PR, waiting for approvals.

Is there something else I can do to merge this one?

Thanks a lot

[KTamas]

Hi, is there an update on this? We're running into this exact issue and merging this PR would solve it.

[tao12345666333]

Moving ingress objects between namespaces without downtime

I believe that this use case has practical significance.

Please resolve the conflicts.

[Fsero]

done @tao12345666333

[Fsero]

@strongjz @rikatz @cpanato is there something else I can do to merge this one?

Thanks a lot

[cpanato]

lets wait a bit more on this, i will discuss that with @rikatz when we both have a time

[tao12345666333]

We can add it to the list for our next community meeting. @strongjz

[Fsero]

We can add it to the list for our next community meeting. @strongjz

hey! any news on this?

thanks so much

[airhorns]

What's the hesitation on this? It seems super valuable to me -- happy to provide more feedback about why if that'd be helpful!

[Fsero]

@strongjz @rikatz @cpanato sometime has passed and this one it's still open, do you need something else that I can do?

Thanks!