net: InterfaceAddrs() "no such network interface" with rapidly changes interfaces

[uablrek]

What version of Go are you using (go version)?

$ go version
go version go1.17.6 linux/amd64

The problem is in Kubernetes v1.23.3 which I think uses go1.17.6, but at least go1.17.x.

Does this issue reproduce with the latest release?

N/A. Have to wait for K8s.

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
# (can't run this in K8s container)

System is openstack with;

Linux control-plane-n108-mast-n057 5.3.18-24.99-default #1 SMP Sun Jan 23 19:03:51 UTC 2022 (712a8e6) x86_64 x86_64 x86_64 GNU/Linux

What did you do?

In heavy stress tests on a very large K8s cluster (159 nodes) the update of addresses made by the internal k8s load-balancer (kube-proxy) sometimed (very infrequent) fails to read all addresses with net.InterfaceAddrs. The error is;

E0209 12:18:47.395530       1 proxier.go:1110] "Failed to list all node IPs from host" err="error listing LOCAL type addresses from host, error: Could not get addresses: route ip+net: no such network interface"

The stress test contantly reboot nodes and interfaces are created and removed all the time. At very infrequent times the error above i thrown.

Please see the K8s issue for more info, kubernetes/kubernetes#108065

What did you expect to see?

No interface related errors thrown by net.InterfaceAddrs, even if interfaces are created/removed all the time.

My interpretation is that the error is thrown if net.InterfaceAddrs firsts reads an interface name, then when to read addresses, the interface is gone.

A "no such network interface" must be handled (ignored) internally in net.InterfaceAddrs.

We as a users can of course add re-tries, but how many and for how long? Since interfaces are created/removed all the time we may never be able to read the addresses.

What did you see instead?

The error described above.

[uablrek]

A work-around may be to read interfaces with net.Interfaces and then read addresses per interface with net.Interface.Addrs and create our own "safe InterfaceAddrs". But IMO we shouldn't have to do that.

[seankhliao]

cc @ianlancetaylor @neild