Check if interface exists and is writeable before trying to configure

[schans]

Description

Bug fix for https://github.com/projectcalico/calico/issues/5348

Related issues/PRs

fixes https://github.com/projectcalico/calico/issues/5348

Todos

• [ ] Tests
• [ ] Documentation
• [ ] Release note

Release Note

Rework logging around sysctls for running Calico in non-privileged mode.

[CLAassistant]

All committers have signed the CLA.

[mgleung]

/sem-approve

[mgleung]

@schans changes look good to me. I think there are some tweaks to our tests to uptake the changes that need to be made but once that's done, we should be good to merge.

[caseydavenport]

Seeing these test failures still:

mmarizing 8 Failures:01:52
[Fail] EndpointManager IPv6 workload endpoints with a workload endpoint [It] should report endpoint down 01:52
/go/src/github.com/projectcalico/calico/felix/dataplane/linux/endpoint_mgr_test.go:168001:52
[Fail] EndpointManager IPv6 workload endpoints with a workload endpoint with updates for the workload's iface [It] should report endpoint up 01:52
/go/src/github.com/projectcalico/calico/felix/dataplane/linux/endpoint_mgr_test.go:172601:52
[Fail] EndpointManager IPv6 workload endpoints with a workload endpoint with updates for the workload's iface [It] should write /proc/sys entries 01:52
/go/src/github.com/projectcalico/calico/felix/dataplane/linux/endpoint_mgr_test.go:199101:52
[Fail] EndpointManager IPv6 workload endpoints with a workload endpoint with updates for the workload's iface changing the endpoint to another up interface [It] should report endpoint up 01:52
/go/src/github.com/projectcalico/calico/felix/dataplane/linux/endpoint_mgr_test.go:186901:52
[Fail] EndpointManager IPv4 workload endpoints with a workload endpoint [It] should report endpoint down 01:52
/go/src/github.com/projectcalico/calico/felix/dataplane/linux/endpoint_mgr_test.go:168001:52
[Fail] EndpointManager IPv4 workload endpoints with a workload endpoint with updates for the workload's iface [It] should report endpoint up 01:52
/go/src/github.com/projectcalico/calico/felix/dataplane/linux/endpoint_mgr_test.go:172601:52
[Fail] EndpointManager IPv4 workload endpoints with a workload endpoint with updates for the workload's iface [It] should write /proc/sys entries 01:52
/go/src/github.com/projectcalico/calico/felix/dataplane/linux/endpoint_mgr_test.go:199101:52
[Fail] EndpointManager IPv4 workload endpoints with a workload endpoint with updates for the workload's iface changing the endpoint to another up interface [It] should report endpoint up 01:52
/go/src/github.com/projectcalico/calico/felix/dataplane/linux/endpoint_mgr_test.go:1869

@schans you should be able to run those locally with make -C felix ut

[caseydavenport]

@schans are you still planning to work on this PR? Has some failing tests

[schans]

Hi!

I'm very sorry I haven't had time to spend on this yet. A vacation and work priorities took up all my time. I hope to revisit soonish.

Thanks Bart

[caseydavenport]

@schans gentle reminder about this one - looks like it just needs a rebase and some test fixes.

[mgleung]

Sounds like this is working as expected. I'm going to close this since it doesn't seem like we have much activity here but feel free to shout out and we can revisit this again.