[Release 1.26] Tailscale dualstack support on single stack node

[rbrtbnfgl]

Backport #8459

[VestigeJ]

##Environment Details
COMMIT=931efc4b7dcc50fca9f294c18afd8f759822b948

Reproduced over here - #8459

Infrastructure

• Cloud

Node(s) CPU architecture, OS, and version:

Linux 5.14.21-150500.53-default x86_64 GNU/Linux
PRETTY_NAME="SUSE Linux Enterprise Server 15 SP5"

Cluster Configuration:

NAME               STATUS   ROLES                       AGE   VERSION
ip-1-131-16-13     Ready    control-plane,etcd,master   18m   v1.26.9+k3s-931efc4b
ip-1-131-16-16     Ready    control-plane,etcd,master   17m   v1.26.9+k3s-931efc4b
ip-1-131-17-13     Ready    control-plane,etcd,master   17m   v1.26.9+k3s-931efc4b
ip-1-131-13-49     Ready    <none>                      18m   v1.26.9+k3s-931efc4b

Config.yaml:

write-kubeconfig-mode: 644
debug: true
token: YOUR_TOKEN_HERE
selinux: true
node-external-ip: 100.100.25.18,fade:iced:a1e0:ba55:ba55:ca5e:ca5e:4b88
node-ip: 100.100.25.18,fade:iced:a1e0:ba55:ba55:ca5e:ca5e:4b88
protect-kernel-defaults: true
cluster-init: true
cluster-cidr: 10.42.0.0/16,2001:cafe:42:0::/56
service-cidr: 10.43.0.0/16,2001:cafe:42:1::/112
vpn-auth: "name=tailscale,joinKey=tskey-auth-MINDCNTRLBASS-crankykaren"

VALIDATION STEPS

$ curl https://get.k3s.io --output install-"k3s".sh
$ sudo chmod +x install-"k3s".sh
$ sudo groupadd --system etcd && sudo useradd -s /sbin/nologin --system -g etcd etcd
$ sudo modprobe ip_vs_rr
$ sudo modprobe ip_vs_wrr
$ sudo modprobe ip_vs_sh
$ sudo printf "on_oovm.panic_on_oom=0 \nvm.overcommit_memory=1 \nkernel.panic=10 \nkernel.panic_ps=1 \nkernel.panic_on_oops=1 \n" > ~/90-kubelet.conf
$ sudo cp 90-kubelet.conf /etc/sysctl.d/
$ sudo systemctl restart systemd-sysctl
$ get_tailscale //curl install tailscale
$ sudo tailscale up --accept-routes
$ ip a
$ conf //sudo vim /etc/rancher/k3s/config.yaml add node-ip/external with ts addrs
$ sudo INSTALL_K3S_COMMIT=931efc4b7dcc50fca9f294c18afd8f759822b948 INSTALL_K3S_EXEC=server ./install-k3s.sh
$ kgn //kubectl get nodes
$ watch -n 2 kg no,po,svc -A 
$ get_report //generate this template

Results:

All pods, services, and nodes healthy, routing tables populated as expected

$ ip route show table 52

10.42.1.0/24 dev tailscale0
10.42.2.0/24 dev tailscale0
10.42.3.0/24 dev tailscale0
100.100.34.35 dev tailscale0
100.100.69.95 dev tailscale0
100.100.97.47 dev tailscale0
100.100.12.96 dev tailscale0
100.100.19.11 dev tailscale0
100.100.16.90 dev tailscale0
100.100.15.18 dev tailscale0
100.100.25.18 dev tailscale0
100.100.10.00 dev tailscale0
100.100.67.42 dev tailscale0
100.100.24.86 dev tailscale0
100.100.17.97 dev tailscale0