Allow multi-CNI setups to set usesSecondaryIP

[ravens]

This PR removes a previously introduced check on the CNI plugin presence.

The original PR #8617 seems to introduce some checks on the use of incompatible CNI plugins, but in fact the CNI plugin is used to set the --node-ip Kubelet option in case the useSecondaryIP flag is set to true. A Kops cluster operator should be able to declare that when using a CNI plugin like Calico for example.

[k8s-ci-robot]

Welcome @ravens!

It looks like this is your first PR to kubernetes/kops 🎉. Please refer to our pull request process documentation to help your PR have a smooth ride to approval.

You will be prompted by a bot to use commands during the review process. Do not be afraid to follow the prompts! It is okay to experiment. Here is the bot commands documentation.

You can also check if kubernetes/kops has its own contribution guidelines.

You may want to refer to our testing guide if you run into trouble with your tests not passing.

If you are having difficulty getting your pull request seen, please follow the recommended escalation practices. Also, for tips and tricks in the contribution process you may want to read the Kubernetes contributor cheat sheet. We want to make sure your contribution gets all the attention it needs!

Thank you, and welcome to Kubernetes. 😃

[k8s-ci-robot]

Hi @ravens. 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 /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.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[olemarkus]

This option does prevent the install of incompatible networking options. The check you remove in this PR would allow specifying a user-managed CNI in addition to a kOps-managed CNI (or kubeet-like networking), which kOps cannot support.

You can however set spec.networking.cni and manage two CNIs independently yourself.

Could you elaborate more on your usecase for this?

[ravens]

This case (cni + another cni) used to work with kops 1.17 - our use case on AWS is to use calico as main CNI and to use Multus to bring ENI to specific pods. Without the CNI option setup, Kubelet does not set up the --node-ip option and Kubelet starts to grab up all the IPs, creating duplicate internalIPs after a while.

While I do see some CNI options being incompatible (i.e. Calico + Cilium), this particular one should not be marked as incompatible IMO.

[olemarkus]

So it is actually spec.networking.cni.usesSecondaryIP that you want to configure. It is perhaps not placed in the in the best struct for this ...

I think maybe if you move this if block below kopeio and remove the optionTaken = true part from the block we achieve what we want. CNI cannot be combined with kubenet-like networking (a lot of the code in kOps would break over this), but it can be combined with any actual CNIs.

[olemarkus]

/cc @hakman
you may have an opinion on this as well, perhaps

[ravens]

@olemarkus thanks for the suggestion ! Indeed the focus is actually on the spec.networking.cni.usesSecondaryIP option. I amended the PR to reflect your proposal.

[olemarkus]

Thanks. Lets see if anyone else has any comments. If not, I'll merge in not too long.

/assign

[hakman]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: olemarkus

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [olemarkus]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[hakman]

/ok-to-test