[Release-1.26] - Error log when trying to find the interface comes without the interface

[manuelbuil]

Backport fix for Error log when trying to find the interface comes without the interface

• Error log when trying to find the interface comes without the interface #8345

[fmoral2]

Validated on Version:

-$  k3s version v1.26.9+k3s-f8f888f4 (f8f888f4)

Environment Details

Infrastructure
Cloud EC2 instance

Node(s) CPU architecture, OS, and Version:
Ubuntu 22.04
Windows 2019

Cluster Configuration:
1 node servers

Steps to validate the fix

1. Install k3s passing the flag for flannel interface with a mock one and another with a non-existing one
2. Check logs of failure
3. Need to find the interface name in the logs

Issue reprodution:

There is no interface named test on the node.

-$ curl https://get.k3s.io | INSTALL_K3S_COMMIT=xxxxxxx  sh -s - server --cluster-init --flannel-iface=test

Sep 27 15:37:58 ip-172-31-26-165 sh[17555]: Failed to get unit file state for nm-cloud-setup.service: No such file or directory
Sep 27 15:37:58 ip-172-31-26-165 k3s[17558]: time="2023-09-27T15:37:58Z" level=warning msg="unable to get global unicast ip from interface name: route ip+net: no such network interface"
Sep 27 15:37:58 ip-172-31-26-165 k3s[17558]: time="2023-09-27T15:37:58Z" level=fatal msg="invalid node-ip: invalid ip format ''"

Validation Results:

There is no interface named test on the node.

-$ curl https://get.k3s.io | INSTALL_K3S_COMMIT=xxxxxxxx  sh -s - server --cluster-init --flannel-iface=test

Sep 27 k3s[19315]: time="2023-09-27T15:42:39Z" level=fatal msg="interface test does not have a correct global unicast ip: route ip+net: no such network interface"




-$ create test interface mock
sudo ip link add name dummy0 type dummy
sudo ip link set dev dummy0 up

-$ curl https://get.k3s.io | INSTALL_K3S_COMMIT=xxxxxxxxxx  sh -s - server --cluster-init --flannel-iface=dummy0




Sep 27 k3s[10569]: time="2023-09-27T15:21:07Z" level=fatal msg="interface dummy0 does not have a correct global unicast ip: can't find ip for interface dummy0"