Status: Add support for multiple Node IP addresses.

[agusdallalba]

What this PR does / why we need it:

The --update-status functionality is extremely useful in "stretched", bare metal, and minimalistic k8s deployments, because it lets us do simple DNS load balancing in conjunction with external_dns or k8s_gateway with no single points of failure.

What updateStatus does is set ingress.status.loadBalancer.ingress.ip[] to the address of every node that's running the ingress-nginx controller.

However, in dual stack clusters (or any clusters where nodes have more than 1 IP address) updateStatus picks only the first address of each node. So we end up with a single-stack Ingress even though the node is reachable on both IPv4 and IPv6 addresses.

This PR addresses this limitation and makes the controller publish every appropriate address of the node to the Ingress status.

I took care to preserve the previous behaviour where:

• When --report-node-internal-ip-address is true, only internal addresses are pushed to the Ingress status.
• When --report-node-internal-ip-address is false, only external addresses are pushed to the Ingress status, unless,
• When --report-node-internal-ip-address is false, and the node has 0 external addresses, internal addresses are picked instead.

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

How Has This Been Tested?

I added more tests, ran make test, make build, make image, and pushed to a cluster to try it out and confirm that it works as I expect it to.

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.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: agusdallalba / name: Agustín Dall'Alba (ff9c214)
• ✅ login: Gacko / name: Marco Ebert (08f3880)

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[k8s-ci-robot]

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[k8s-ci-robot]

Hi @agusdallalba. Thanks for your PR.

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[Gacko]

/retitle Status: Add support for multiple Node IP addresses.
/triage accepted
/kind feature
/priority backlog
/lgtm

[Gacko]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: agusdallalba, Gacko

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