[Release-1.28] - Load balancer crashing with IPv6 disabled

[brandond]

Backport fix for Load balancer crashing with IPv6 disabled

• Load balancer crashing with IPv6 disabled #10455

[fmoral2]

Validated on Version:

-$ k3s version v1.28.12+k3s-815efbfc (815efbfc)

Environment Details

Infrastructure
Cloud EC2 instance

Node(s) CPU architecture, OS, and Version:
PRETTY_NAME="Ubuntu 22.04.1 LTS"
NAME="Ubuntu"
VERSION_ID="22.04"

Cluster Configuration:
1 node server

Steps to validate the fix

1. Installed K3s
2. Host has IPv6 disabled - ipv6.disable=1 in GRUB_CMDLINE_LINUX and the following sysctl settings set to 1:

net.ipv6.conf.all.disable_ipv6
net.ipv6.conf.default.disable_ipv6
net.ipv6.route.flush

3. Validate that the svclb-traefik is created and working as expected
4. Validate pods

Reproduction Issue:

 


 $ journalctl -xeu k3s.service -f  

efik-a2a52733-2cf9m_kube-system(a02450da-9888-46c6-9460-2dee9d85a4b2)\\\": rpc error: code = Unknown desc = failed to create containerd task: failed to create shim task: OCI runtime create failed: runc create failed: unable to start container process: error during container init: open /proc/sys/net/ipv6/conf/all/forwarding: no such file or directory: unknown\"" pod="kube-system/svclb-traefik-a2a52733-2cf9m" podUID="a02450da-9888-46c6-9460-2dee9d85a4b2"
Aug 09 13:32:43  k3s[1336]: W0809 13:32:43.734670    1336 manager.go:1169] Failed to process watch event {EventType:0 Name:/kubepods.slice/kubepods-besteffort.slice/kubepods-besteffort-poda02450da_9888_46c6_9460_2dee9d85a4b2.slice/cri-containerd-8183720517ca633ad3022bf397d0d2e98f71c41651b78fa8d036c4f5723ec25c.scope WatchSource:0}: container "8183720517ca633ad3022bf397d0d2e98f71c41651b78fa8d036c4f5723ec25c" in namespace "k8s.io": not found

Validation Results:

 

kube-system   metrics-server-54fd9b65b-vcrfq            0/1     Running     0          24s
kube-system   svclb-traefik-18732769-96dh5              2/2     Running     0          8s
kube-system   traefik-7d5f6474df-44hk2                  1/1     Running     0          8s