Fix HostAlias to validate against DNS1123 hostname instead of just labels

[evie404]

What this PR does / why we need it: the validation for HostAlias was validating the hostnames against DNS labels instead of hostnames. This means hostnames like foo.bar would fail. I did not catch this because unit test cases only had hostnames like foo.

Which issue this PR fixes: fixes issue introduced in #44641

Release note:

fixed HostAlias in PodSpec to allow `foo.bar` hostnames instead of just `foo` DNS labels.

[k8s-ci-robot]

Hi @rickypai. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with @k8s-bot ok to test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[piosz]

@bowei could you please take a look or find an owner?

[cmluciano]

@k8s-bot ok to test

[cmluciano]

Not sure if that unit test is a flake or not. I have been hitting frequently today.

[evie404]

listen tcp 127.0.0.1:42436: bind: address already in use

seems to be problems related to the test setup :(

[bowei]

/lgtm

[bowei]

Should be a bugfix for 1.7?

[evie404]

yes this is a fix for a 1.7 feature and should be backported.

[evie404]

so all tests passed. submit queue is not taking it because "Milestone is for a future release and cannot be merged". should a milestone tag be added?

[bowei]

@kubernetes/kubernetes-release-managers

[cmluciano]

/kind bug

[evie404]

does this need to be added to v1.7 milestone? i'm not very familiar with the project structure

[dchen1107]

/approve no-issue

[dchen1107]

cc/ @kubernetes/kubernetes-release-managers

[bowei]

/lgtm

[k8s-github-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: bowei, dchen1107, rickypai

Associated issue: 44641

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Needs approval from an approver in each of these OWNERS Files:

• pkg/api/OWNERS [dchen1107]

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[k8s-github-robot]

Automatic merge from submit-queue (batch tested with PRs 46977, 47005, 47018, 47061, 46809)