flannel-v6.1 MAC address changes every boot about k3s HOT 9 OPEN

cc @manuelbuil.

This may belong in https://github.com/flannel-io/flannel

from k3s.

Thanks for reporting this! I don't think this is a regression. Flannel was picking a new mac address for the vxlan interface in each reboot and this was fixed with this PR: flannel-io/flannel#1829. But it seems the user missed to add the same logic to the v6 interface

from k3s.

flannel-io/flannel#1946

from k3s.

Thank you for making that PR, @manuelbuil. Just for my understanding, can you expand on how this isn't a regression? i.e. how have I never experienced this problem? By "problem" I mean the broken flannel network, not the changing MAC. I just assumed the broken network was due to the changing MAC, but it looks like prior to flannel-io/flannel#1829 both interfaces' MAC should have been changing, which means that either I (and everyone else using flannel) should have experienced this issue on every reboot I've done, or I'm missing something.

Do you expect flannel to actually be able to handle changing MAC addresses? If so, that functionality appears to have broken somehow. Did k3s change the config to make the interfaces non-learning, perhaps? That might be worth looking into, although once your PR lands it looks like neither interface should be changing anymore.

from k3s.

Thank you for making that PR, @manuelbuil. Just for my understanding, can you expand on how this isn't a regression? i.e. how have I never experienced this problem? By "problem" I mean the broken flannel network, not the changing MAC. I just assumed the broken network was due to the changing MAC, but it looks like prior to flannel-io/flannel#1829 both interfaces' MAC should have been changing, which means that either I (and everyone else using flannel) should have experienced this issue on every reboot I've done, or I'm missing something.

Do you expect flannel to actually be able to handle changing MAC addresses? If so, that functionality appears to have broken somehow. Did k3s change the config to make the interfaces non-learning, perhaps? That might be worth looking into, although once your PR lands it looks like neither interface should be changing anymore.

My understanding is that before the user's PR, MAC addresses were changing in each reboot. I don't think K3s is changing any default kernel behaviour, so yes, the bug should have been present in K3s. Maybe linux networking components were able to re-learn the new MAC address quickly except in certain environments? It could be a nice investigation to do, I agree

from k3s.

Huh, how odd. Doesn't really matter I guess, your flannel PR will fix the issue. Any idea when that will be contained in a k3s release?

from k3s.

Huh, how odd. Doesn't really matter I guess, your flannel PR will fix the issue. Any idea when that will be contained in a k3s release?

It should be included in the May release. We are currently under code freeze for the April release

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Hi @manuelbuil Is there a potential workaround for Canal on RHEL 8.8 until release? A previous issue had recommended updating flannel config to macaddresspolicy to none but not sure if this would work as /etc/systemd/network doesn't exist on my RHEL nodes and this is an RKE2 system running Canal. We are using IPv6 as our primary pod to pod traffic.

cat<<'EOF'>/etc/systemd/network/10-flannel.link
[Match]
OriginalName=flannel*

[Link]
MACAddressPolicy=none
EOF

flannel-io/flannel#1155

from k3s.

Hi @manuelbuil Is there a potential workaround for Canal on RHEL 8.8 until release? A previous issue had recommended updating flannel config to macaddresspolicy to none but not sure if this would work as /etc/systemd/network doesn't exist on my RHEL nodes and this is an RKE2 system running Canal. We are using IPv6 as our primary pod to pod traffic.

cat<<'EOF'>/etc/systemd/network/10-flannel.link [Match] OriginalName=flannel*

[Link] MACAddressPolicy=none EOF

flannel-io/flannel#1155

Yes, you could use the new flannel image once it is ready. We are waiting on one extra PR to be merged in Flannel and then we will release v0.25.2 with the fix

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