2023-09-06: Prometheus server unresponsive in ops environment
Customer Impact
No customer impact. Metrics collection for our internal ops environment was temporarily degraded.
Current Status
Both prometheus servers in the ops environment (not gprd) became unexpectedly unresponsive for a few minutes. This was triggered by an expensive thanos query driving a large spike in memory pressure, leading indirectly to also saturating both CPU usage and disk IO (specifically reads from the ops-data disk, sdb). See summary notes: #16313 (comment 1546298226).
This saturation temporarily degraded metrics collection in the ops environment, causing a gap in metrics collection lasting for 4 minutes and 12 minutes respectively on the two affected prometheus servers.
📚 References and helpful links
Recent Events (available internally only):
- Feature Flag Log - Chatops to toggle Feature Flags Documentation
- Infrastructure Configurations
- GCP Events (e.g. host failure)
Deployment Guidance
- Deployments Log | Gitlab.com Latest Updates
- Reach out to Release Managers for S1/S2 incidents to discuss Rollbacks, Hot Patching or speeding up deployments. | Rollback Runbook | Hot Patch Runbook
Use the following links to create related issues to this incident if additional work needs to be completed after it is resolved:
- Corrective action ❙ Infradev
- Incident Review ❙ Infra investigation followup
- Confidential Support contact ❙ QA investigation
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