Tinkerbell LoadBalancerInterface doesn't set tink-stack srcInterface

[MatiasLyyra]

In the release v0.21.0 it became possible to set Tinkerbell loadBalancerInterface. While it sets the vip_interface in kube-vip correctly to the specified interface, it doesn't change srcInterface variable from tink-stack deployment.

Snippet from the tink-stack deployment:

      - command:
        - /bin/sh
        - -c
        - |
          # This script allows us to listen and respond to DHCP requests on a host network interface and interact with Smee properly.
          # This is used instead of `hostNetwork: true` because the dhcp relay requires clear paths for listening for broadcast traffic
          # and sending/receiving unicast traffic to/from Smee.
          set -xe
          # if sourceInterface is not set use the interface from the default route
          srcInterface=""
          if [ -z "$srcInterface" ]; then
            srcInterface=$(nsenter -t1 -n ip route | awk '/default/ {print $5}' | head -n1)
          fi
          # Create the interface. TODO: If this fails, try again with a different name?
          nsenter -t1 -n ip link add macvlan0 link ${srcInterface} type macvlan mode bridge
          # Move the interface into the POD.
          pid=$(echo $$)
          nsenter -t1 -n ip link set macvlan0 netns ${pid} || nsenter -t1 -n ip link delete macvlan0
          # Set the interface up
          ip link set macvlan0 up
          # Set the IP address
          ip addr add 127.1.1.1/32 dev macvlan0 noprefixroute || true

If the srcInterface in that script is not set, it defaults to the interface with default route, which breaks DHCP relaying unless it is changed manually.

What happened:
Variable srcInterface is not set to the same interface as Tinkerbell loadBalancerInterface variable.

What you expected to happen:
Variable srcInterface in tink-stack deployment config is set to the same value as Tinkerbell loadBalancerInterface variable.

How to reproduce it (as minimally and precisely as possible):

1. Create cluster with Tinkerbell loadBalancerInterface set.
2. Observe the resulting tink-stack deployment config: kubectl get deployments.apps -n eksa-system tink-stack -o yaml.

Environment:

• EKS Anywhere Release: v0.21.1
• EKS Distro Release: 1.30