Systemd service for k3s to take tailscale IP as node ip

k3s-nodeip-tailscale.service.j2

[Unit]
Description=Generates K3S NodeIP Entry With Tailscale IP
Requires=network.target
Requires=tailscaled.service
Before=k3s.service

[Service]
Type=oneshot
RemainAfterExit=yes

# k3s config file
Environment=CONFIG_FILE=/etc/rancher/k3s/config.yaml.d/tailscale.yaml

# wait until tailscale is ready
ExecStartPre=/bin/bash -c 'until tailscale status; do echo waiting for tailscale to be up && sleep 1; done'

# make sure config directory exists
ExecStartPre=/bin/bash -c 'mkdir -p `dirname $CONFIG_FILE`'

# compose configuration file
ExecStart=/bin/bash -c '\
    echo "node-ip: `tailscale ip -4`" > "$CONFIG_FILE"; \
    echo "advertise-address: `tailscale ip -4`" >> "$CONFIG_FILE"; \
    cat "$CONFIG_FILE"'

[Install]
WantedBy=multi-user.target