hack/test-port-forwarding.pl: support socat as listener and writer

[norio-nomura]

support socat as a listener and writer.

$ ./hack/test-port-forwarding.pl default [nc|socat [nc|socat]] [timeout]

The nc command always sets SO_REUSEPORT on the listening TCP port.
The socat command provides a reuseport option that enables SO_REUSEPORT on the listening TCP port.

Ref: #4160 (comment)

In the current code, test-port-forwarding.pl is executed twice in each job using nc and socat for comparison. Dropped an execution using nc.

[norio-nomura]

As far as I can see, tests that failed in nc were also successful in socat.
Is the instability of the port forwarding test caused by nc?

[jandubois]

Is the instability of the port forwarding test caused by nc?

I'm just browsing, but this PR still has failing port forwarding tests, e.g. https://github.com/lima-vm/lima/actions/runs/18364708138/job/52315306508?pr=4170. So it looks like switching to socat does not fix them.

[norio-nomura]

I'm just browsing, but this PR still has failing port forwarding tests, e.g. https://github.com/lima-vm/lima/actions/runs/18364708138/job/52315306508?pr=4170.

This PR does tests using both of nc and socat on the same job.
It has failed only on nc.

[norio-nomura]

I guessed that the reason why nc fails is because the timeout is too short, but even if the timeout is extended to 3 seconds, nc continues to fail.

[norio-nomura]

the history of workflow runs by this PR: https://github.com/lima-vm/lima/actions?query=branch%3Atest-port-forwarding.pl-use-socat+workflow%3Atest

[jandubois]

This PR does tests using both of nc and socat on the same job.

I'm sorry, I missed this.

I would be happy to switch to socat, even on a trial basis, to see if this helps. I'm so tired of re-running tests all the time.

[norio-nomura]

the history of workflow runs by this PR: https://github.com/lima-vm/lima/actions?query=branch%3Atest-port-forwarding.pl-use-socat+workflow%3Atest

To check failed logs in the workflow on local terminal, we can use gh:
gh run list -b test-port-forwarding.pl-use-socat -w test --json conclusion,databaseId --jq '.[]|select(.conclusion=="failure")|.databaseId'|xargs -n 1 -I % sh -c "gh run view % --log-failed|awk '/\/hack\/test-port-forwarding.pl/{start=1};start==1{print}/Port forwarding rules/{start=0}'"

[norio-nomura]

the history of workflow runs by this PR: https://github.com/lima-vm/lima/actions?query=branch%3Atest-port-forwarding.pl-use-socat+workflow%3Atest

To check failed logs in the workflow on local terminal, we can use gh: gh run list -b test-port-forwarding.pl-use-socat -w test --json conclusion,databaseId --jq '.[]|select(.conclusion=="failure")|.databaseId'|xargs -n 1 -I % sh -c "gh run view % --log-failed|awk '/\/hack\/test-port-forwarding.pl/{start=1};start==1{print}/Port forwarding rules/{start=0}'"

I checked the test-port-forwarding.pl's failure log of all runs after 9394 that were able to set up socat correctly, but none of them failed in socat.

[norio-nomura]

https://github.com/lima-vm/lima/actions/runs/18367831847/job/52324053793?pr=4170#step:10:673

time="2025-10-09T06:55:42Z" level=fatal msg="rootless containerd not running? (hint: use containerd-rootless-setuptool.sh install to start rootless containerd): stat /run/user/501/containerd-rootless: no such file or directory"

I often see this failure.

[AkihiroSuda]

Thanks

[norio-nomura]

Thanks! 🙏🏻