tink-stack nginx can't handle IPv6 adresses

[sepauli]

Description

We have an RKE2 cluster running in IPv6 only mode.
During the deployment via the helm chart the tink-stack pod does not start due to the following error message

:~# kubectl logs -n tink-system tink-stack-6bbc556dd-znd6j
Defaulted container "tink-stack" out of: tink-stack, dhcp-relay
++ awk '/nameserver/ {print $2}' /etc/resolv.conf
+ POD_NAMESERVER=fd05:0000:0000::a
+ envsubst '$POD_NAMESERVER'
+ exec nginx -g 'daemon off;'
2024/06/03 16:23:37 [emerg] 3210953#3210953: invalid port in resolver "fd05:0000:0000::a" in /etc/nginx/nginx.conf:13
nginx: [emerg] invalid port in resolver "fd05:0000:0000::a" in /etc/nginx/nginx.conf:13

The reason is that the following bash command cannot handle IPv6 addresses.

        args:
        - |
          POD_NAMESERVER=$(awk '/nameserver/ {print $2}' /etc/resolv.conf) \
            envsubst '$POD_NAMESERVER' \
            </tmp/nginx.conf.template \
            >/etc/nginx/nginx.conf
          exec nginx -g 'daemon off;'

I changed the command to the following one, which works for me

        - export POD_NAMESERVER=$(awk 'NR==2 {print $2}' /etc/resolv.conf);
          [[ $POD_NAMESERVER == *.* ]] || POD_NAMESERVER="[$POD_NAMESERVER]";
          envsubst '$POD_NAMESERVER' < /tmp/nginx.conf.template > /etc/nginx/nginx.conf;
          nginx -g 'daemon off;'

I can open a PR if you want

To Reproduce

Deploy an RKE2 Cluster in IPv6 only mode and try to deploy the helm-chart