Can't have a certificate in both the default certificate and additional certificate for SNI

[jebeaudet]

Describe the bug
Currently, using the certificate-arn annotation, it is not possible to have a certain certificate as the default certificate AND in the additional certificate list for SNI. Here is what I'm trying to do in the console (I've tried manually and it's permitted) :

Steps to reproduce
Add an ingress with the following certificate-arn:

    alb.ingress.kubernetes.io/certificate-arn: arn:aws:acm:us-east-1:1234:certificate/bb08f8b3-967c-46d1-91f8-07b08a5dad9c,arn:aws:acm:us-east-1:1234:certificate/d4b002c2-5e06-4051-9d0f-8ccfa9cff5f1,arn:aws:acm:us-east-1:1234:certificate/bb08f8b3-967c-46d1-91f8-07b08a5dad9c

Expected outcome
A valid configuration like this (this was done manually in the aws console, you can see the same cert as the default and in the SNI section) :

Environment

• AWS Load Balancer controller version 2.4.6
• Kubernetes version 1.22
• Using EKS (yes/no), if so version? yes

Additional Context:
I think the problem comes from the code who's merging multiple potential ingress resources, it uses a set for the merge strategy and this end up in stripping an extra certificate here https://github.com/kubernetes-sigs/aws-load-balancer-controller/blob/main/pkg/ingress/model_builder.go#L328

Thanks

[oliviassss]

Hi @jebeaudet, I'm just trying to understand why would you like one certificate to appear in both default and additional cert list? Can you please elaborate more on the use case? Thanks.

[jebeaudet]

Hi @oliviassss

Because the default certificate is used only when the client doesn't support SNI or when the SNI request does not match any certificate in the additional certificate lists. This is documented here. Therefore, if you want your default certificate to server as a potential SNI target, it needs to be in both places.

To quote another of AWS documentation page :

You can optionally add the default certificate to ensure that this certificate is used with the SNI protocol even if it is replaced as the default certificate
https://docs.aws.amazon.com/elasticloadbalancing/latest/application/listener-update-certificates.html

[oliviassss]

@jebeaudet thanks, checking on that

[kahirokunn]

I need this

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/lifecycle stale

[kahirokunn]

keep

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues.

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/lifecycle rotten

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues and PRs.

This bot triages issues according to the following rules:

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/close not-planned

[k8s-ci-robot]

@k8s-triage-robot: Closing this issue, marking it as "Not Planned".

In response to this:

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues and PRs.

This bot triages issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Reopen this issue with /reopen
• Mark this issue as fresh with /remove-lifecycle rotten
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/close not-planned

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[kahirokunn]

/reopen