Cache and print devices for debugging future outages

[julianKatz]

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespaces from that line:

/kind api-change
/kind bug

/kind cleanup # Is this right??

/kind design
/kind documentation
/kind failing-test
/kind feature
/kind flake

What this PR does / why we need it:

This PR adds a cache that periodically (configured to every minute currently) looks at the /dev/disk/by-id/ directory and evaluates the symlinks there. It maintains a cache of the symlink and the real path it points to.

This will help with debugging future filesystem issues. In a past OMG, we found that our insight into changes in symlinks for specific disks hampered our ability to debug. Logging marked the real path of the disk at mount and unmount, but the change in between couldn't be detected.

This PR will print those links every minute, also logging when elements of the cache change.

An example:

I0521 00:23:51.418261      12 cache.go:62] periodic symlink cache read: /dev/disk/by-id/google-persistent-disk-0 -> /dev/sda; /dev/disk/by-id/google-pvc-f5418f78-dc07-4d69-9487-6c4a7232dd67 -> /dev/sdb; /dev/disk/by-id/scsi-0Google_PersistentDisk_persistent-disk-0 -> /dev/sda; /dev/disk/by-id/scsi-0Google_PersistentDisk_pvc-f5418f78-dc07-4d69-9487-6c4a7232dd67 -> /dev/sdb

The cache will also note if a symlink is broken.

NOTE: Currently this filters out any thing in by-id/ that ends with -part[0-9]*$. This removes partitions, which are noise. Mounting partitions directly isn't well supported in GKE, but we may want to test that in the future.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

None

[k8s-ci-robot]

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[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: julianKatz
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[julianKatz]

/ok-to-test

[tonyzhc]

/lgtm

[k8s-ci-robot]

New changes are detected. LGTM label has been removed.

[julianKatz]

This seems to no longer be necessary on cloudtop, and was actively causing my local test run to fail.

[julianKatz]

/retest

[cemakd]

/retest

[k8s-ci-robot]

PR needs rebase.

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[k8s-ci-robot]

@julianKatz: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-gcp-compute-persistent-disk-csi-driver-e2e	5832ea4	link	true	/test pull-gcp-compute-persistent-disk-csi-driver-e2e
pull-gcp-compute-persistent-disk-csi-driver-e2e-windows-2022	5832ea4	link	false	/test pull-gcp-compute-persistent-disk-csi-driver-e2e-windows-2022
pull-gcp-compute-persistent-disk-csi-driver-e2e-arm	5832ea4	link	true	/test pull-gcp-compute-persistent-disk-csi-driver-e2e-arm

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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[sunnylovestiramisu]

Not under active development anymore.