Support Debian 11 Bullseye

[ReillyBrogan]

Add support for Debian 11 ahead of the impending release on August 14th.

Tested by creating a cluster with the debian-11-amd64-daily-20210805-725 image and verifying that both the cluster came up and that node logs did not contain any errors. Tested kubenet and cilium networking and both containerd and docker runtimes.

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[ReillyBrogan]

I signed it

[hakman]

/ok-to-test

[johngmyers]

I think this deserves a release note.

Perhaps we should bake in the switch to iptables?

[hakman]

I think this deserves a release note.

For sure :).

Perhaps we should bake in the switch to iptables?

This is optional, works well without it too. I think most CNI plugins support it these days. It is the default in newer Ubuntu too. Probably the should be rephrased.

[ReillyBrogan]

I think this deserves a release note.

For sure :).

I looked at the commit history of the releases directory, I assume PR authors are not usually expected to add those entries to their commits? (I can if that's helpful)

Perhaps we should bake in the switch to iptables?

This is optional, works well without it too. I think most CNI plugins support it these days. It is the default in newer Ubuntu too. Probably the should be rephrased.

Looks like kube-proxy supports it as of 1.17, so with the drop of 1.15 and 1.16 this release all supported versions of Kubernetes have the fix. I took a look at the various CNI plugins and the following all have auto-detection:

• Cilium (and especially when running in kube-proxy replacement mode)
• Weave-net
• Flannel
• kube-router

Calico allows configuration of the mode to be in but does not have auto-detection from what I can find.

I have no idea what the situation is with Canal with only Flannel supporting auto-detection, but I suspect you would need to manually set Calico to the correct value as well.

I was unable to find a PR or even an issue for aws-vpc or lyft-vpc, perhaps it was never an issue with those?

I think the entire section on iptables can probably be deleted from both Buster and Bullseye and perhaps moved to the Calico/Canal docs as it looks like that's the only place it's still relevant.

[hakman]

I agree that the iptables section can be removed from Bullseye. Buster implementation has various bugs and performance issues that were never addressed.

Calico has support for NFT and autodetection:

kops/upup/models/cloudup/resources/addons/networking.projectcalico.org/k8s-1.16.yaml.template

Lines 4110 to 4111 in 1d42125

	- name: FELIX_IPTABLESBACKEND
	value: "{{- or .Networking.Calico.IptablesBackend "Auto" }}"

Canal... needs a maintainer :).
Lyft... will be removed soon.

[ReillyBrogan]

I agree that the iptables section can be removed from Bullseye

This is done.

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This pull-request has been approved by: johngmyers

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