periodic errors exporting logs

[BenTheElder]

we're seeing errors tarring up log files for exporting the logs
/assign
/priority important-soon
/lifecycle active

xref previously: #949

[BenTheElder]

having some difficulty triggering this now that i'm trying to fix it 😛

[BenTheElder]

Got it once on the generic test PR, haven't gotten it again on the debug PR
https://prow.k8s.io/view/gcs/kubernetes-jenkins/pr-logs/pull/sigs.k8s.io_kind/648/pull-kind-conformance-parallel-1-13/1187394260584894464/

[BenTheElder]

#1014

[BenTheElder]

reopening to keep an eye on this actually being fixed.

[BenTheElder]

looking into this again today. I think I have a better idea what the root cause may be, finally getting back to verifying 🤞

[BenTheElder]

ERROR: [command "docker exec --privileged kind-worker tar --hard-dereference -C /var/tmp/tmp.EqvsHf65G9 -chf - ." failed with error: write |1: broken pipe, command "docker exec --privileged kind-control-plane tar --hard-dereference -C /var/tmp/tmp.gLnoymvPuz -chf - ." failed with error: exit status 1]

still a thing https://prow.k8s.io/view/gcs/kubernetes-jenkins/pr-logs/pull/kubernetes-sigs_kind/1059/pull-kind-e2e-kubernetes/1191980418304315397

[BenTheElder]

I can repro locally

[BenTheElder]

so there's null bytes at the end. I think the go tar reader exits early when it's done reading through the tar contents but before the tar util is done writing more null or similar.

we probably just need to read and discard the end