client checks kernel module in /sys/module for WSL2 bridge networking

[jeteve]

This is a solution for issue #17305 and will enable nomad to have greater chances to detect the bridge kernel module on WSL2 hosts, thus enabling bridge networking.

Closes #17305

[hashicorp-cla]

All committers have signed the CLA.

[lgfa29]

Thanks for the contribution @jeteve!

I left some minor comments about error handling and variable naming but I was able to get this to work after the small adjustment described in microsoft/WSL#6044 (comment) to enable legacy mode for iptables. Did you run into this as well?

I was also not able to get the docker driver to work (the network pre-run hook fails with the error failed to Statfs "/var/run/docker/netns/...), but that looks like a fix for another time 😄

Using the exec driver in bridge mode worked well 👍

I will also ping @shoenig for another check since he has more experience on this area than me.

[jeteve]

Hi @lgfa29 , thanks a lot for your review. I've pushed some amended code.

[lgfa29]

Changes look good to me, thanks @jeteve!

I just pushed a commit to add a CHANGELOG entry.

[jeteve]

Thanks a lot @lgfa29 , and apologies for skipping the CHANGELOG myself.

I see all checks are good except 'Vercel – nomad'. I assume unblocking this is part of your release flow?

Thanks!

[shoenig]

LGTM!

[lgfa29]

I see all checks are good except 'Vercel – nomad'. I assume unblocking this is part of your release flow?

I tried to approve it a few times but it doesn't seem to be working 😅

But that's not a problem for this PR.