I've looked at this; I believe it's showing up because infra.cron is configured to be a part of the chromium tree (because of gnumbd, originally), and so any failing build on there gets alerted for. It doesn't get filtered out because there isn't a rule to filter it out in gatekeeper.

I think we should remove infra.cron from the chromium tree, and make the trooper deal with these errors instead. 

sgtm, but someone should check if any of the builders on infra.cron really do belong on a chromium waterfall instead.

Gnumbd failures really do need to be visible to sheriffs: if gnumbd being down is the reason no commits are landing on tip-of-tree, they need to know that so they can answer the inevitable questions. Other than that, infra.cron shouldn't be part of the chromium tree.

+stip to help figure out how to correctly set up gatekeeper-ng so only gnumbd is included.

From my understanding, alerts on sheriff-o-matic are supposed to be actionable by the sheriffs, and sheriffs don't know how to (and aren't supposed to) fix gnumbd. That's the troopers job, since it's a cron we run. The troopers job can be to tell the sheriff's it's broken, so they know how to answer the question, but I don't see the point in sending them an alert if they can't fix the problem. There is playbook entry for gnumbd (https://chrome-internal.googlesource.com/infra/infra_internal/+/master/doc/troopers/playbook.md#GnumbdBuilderFailuresAlert), so troopers can be roughly be expected to fix it. 

Gatekeeper's configuration isn't the problem; it's the problem of builder alerts, which is generating these alerts before it applies (the wrong interpretation of) gatekeeper rules.  

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

Sorry for the inconvenience if the bug really should have been left as Available.

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