[dustinkirkland]

What type of PR is this?

/kind bug

What this PR does / why we need it:

With the system-stats monitor enabled, node-problem-detector exits right after startup on Wolfi-based images, because ID=wolfi isn't in the getOSVersion() list and the host collector calls klog.Fatalf on the error:

F1026 16:03:36.590971  7 host_collector.go:44] Failed to retrieve OS version: unsupported ID in /etc/os-release: "wolfi"

This PR:

• handles ID=wolfi the same way as chainguard (added in Add chainguard to list of OSs #1355).
• falls back to VERSION_ID when VERSION isn't set. VERSION is optional in os-release(5), and both Wolfi and Chainguard only set VERSION_ID, so os_version was reported as "chainguard " with a trailing space. Distros that set VERSION are unchanged.
• adds testdata/os-release-wolfi (the current file from cgr.dev/chainguard/wolfi-base) and testdata/os-release-chainguard (the file from Add chainguard to list of OSs #1355), plus test cases for both.

Which issue(s) this PR fixes:

None filed. I can open one if you'd prefer.

Special notes for your reviewer:

Tests:

• On master, the new cases fail: wolfi gets unsupported ID in /etc/os-release: "wolfi", and chainguard returns "chainguard " instead of "chainguard 20230214". With this change, TestGetOSVersionLinux passes.
• go test -race -short ./...: 27 packages ok, both before and after the change.
• I also ran it end to end in a wolfi-base container with --config.system-stats-monitor=config/system-stats-monitor.json --enable-k8s-exporter=false:
  • master exits with the fatal above.
  • with this change it logs "Start system stats monitor" and "Problem detector started", and /metrics shows os_version="wolfi 20230201".

Chainguard carries this patch downstream in its node-problem-detector package. I'd like to drop it once a release includes this.

Prepared with AI assistance (Claude Code); reviewed and tested by the submitter.

Does this PR introduce a user-facing change?

node-problem-detector no longer exits at startup on Wolfi-based hosts when the system-stats monitor is enabled. The os_version label now falls back to VERSION_ID when /etc/os-release has no VERSION field (for example Wolfi and Chainguard).

🤖 Generated with Claude Code

[kubernetes-prow]

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This pull-request has been approved by: dustinkirkland
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