Route ingress: Allow setting termination policy via annotation

[alvaroaleman]

Ingress objects are more common in the Kube ecosystem and have deeper
integration with other components. Right now they can not be used when a
terminationPolicy other than Edge is required. This PR changes that by
allowing to set an annotation on the Ingress.

cc @hongkailiu

[alvaroaleman]

/retest

[alvaroaleman]

/assign @Miciah

[Miciah]

This looks good, but I'd like to discuss it with the team before merging it.

By the way, during review, I was confused about insecureEdgeTerminationPolicy. Although the API documentation implies that insecureEdgeTerminationPolicy is applicable only to edge-terminated routes (https://github.com/openshift/api/blob/af4dd20aed231f81f1c76f0a98dc60947f12a7a4/route/v1/types.go#L250-L257), the validation allows insecureEdgeTerminationPolicy to be used with edge, reencrypt, and passthrough, with the caveat that insecureEdgeTerminationPolicy: Allow is prohibited for passthrough routes (https://github.com/openshift/openshift-apiserver/blob/3dc75d3dd5b8de9487122d4a798ab1600217efb8/pkg/route/apis/route/validation/validation.go#L243-L264).

[alvaroaleman]

@Miciah yeah that we can not validate and provide feedback is not ideal. Does openshift already have a webhook or anything else that can be used to add additional validations for objects served by the kube-apiserver, do you know?

[Miciah]

Does openshift already have a webhook or anything else that can be used to add additional validations for objects served by the kube-apiserver, do you know?

I'm not aware of anything, sorry. I'd ask someone from the API team.

[Miciah]

/lgtm

[openshift-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: alvaroaleman, Miciah

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[openshift-bot]

/retest

Please review the full test history for this PR and help us cut down flakes.

[openshift-bot]

/retest

Please review the full test history for this PR and help us cut down flakes.

[hongkailiu]

@Miciah

Is it possible to backport it 4.5?

[alvaroaleman]

@hongkailiu right now there is a follow-up open to fix some issues with this: #128 That would need to merge first