Linux Gate Detective RCA — build 166961552

Status: CIS regression on Ubuntu 24.04 gen2 containerd; now correlated with a second matching failure shape on PR #8294
Failure: build2404gen2containerd failed CIS baseline comparison: rule 6.1.4.1 pass→fail
Run: https://msazure.visualstudio.com/CloudNativeCompute/_build/results?buildId=166961552

RCA: The first failing step is Test, Scan, and Cleanup via vhdbuilder/packer/test/run-test.sh → vhdbuilder/packer/vhd-scanning.sh, where CIS scan output is compared against the checked-in Ubuntu 24.04 baseline. The regression signature was:

CIS regressions detected: 1
Regression details (rule_id|baseline->current): 6.1.4.1|pass->fail

Rule 6.1.4.1 is "Ensure access to all logfiles has been configured". It scans /var/log and fails if any regular logfile has non-compliant mode/owner/group. The original suspect was the Ubuntu 24.04u2 runc/containerd package bump leaving a new or changed logfile footprint, but the same CIS rule has now shown up on PR #8294 as well, so this looks more like Ubuntu 24.04 baseline/product drift than a uniquely PR-local failure.

Confidence: MEDIUM-HIGH

Next action: compare cis-regressions.txt and the offending /var/log file list between this run and PR #8294 before merging; then either update the baseline/remediation if expected, or fix the package/logfile permissions if unexpected.

AgentBaker Linux PR gate — CIS regression

• Run: 166961552 (partiallySucceeded)
• Failed job/task: build2404gen2containerd → Test, Scan, and Cleanup
• Signature: CIS regressions detected: 1 — rule 6.1.4.1 pass→fail (Ubuntu 24.04 L1: Ensure access to all logfiles has been configured). Only 24.04 gen2 SKU regressed; 12 other SKUs and E2E green.

Likely cause (high confidence, change-caused): the runc/containerd bump in parts/common/components.json (v2.3.1-ubuntu24.04u2) deposits a file under /var/log with mode/owner/group outside the CIS allow-list (commonly mode > 0640 or group ∉ {adm,syslog,utmp,systemd-journal}). PR is the only delta; vhdbuilder/packer/cis/baselines/ubuntu/24.04.txt is unchanged.

Strongest alternative (less likely): baseline staleness for 24.04 — ruled lower because only the targeted SKU regressed in a 13-SKU matrix and the baseline file is unchanged. (Note: a second renovate PR has since hit the same rule — see #8294 — so the baseline-drift hypothesis is now stronger; please coordinate.)

Recommended next action: download cis-regressions.txt from the failed job — it names the exact /var/log path and observed vs expected perms. Then either chmod/chown in the install step (vhdbuilder/packer/install-dependencies.sh), update the 24.04 baseline if intentional, or push back upstream. Owner: PR author / NodeSIG-dev renovate-gate triage.

Posted by Clawpilot AgentBaker gate detective.