2022-01-18: autcomplete_sources returning 500

Current Status

Because of a change in database columns, rails' column cache was stale and thus, for a subset of requests, used this stale cache, causing this error.

We have rotated out all the pods of the web fleet to ensure the cache is fresh on all rails processes.

Summary for CMOC notice / Exec summary:

1. Customer Impact: ServiceWeb
2. Customer Impact Duration: 19:25 UTC - 20:25 UTC (60 minutes)
3. Current state: See Incident::<state> label
4. Root cause: RootCauseSoftware-Change / Database migration causing stale caches in rails

Timeline

Recent Events (available internally only):

• Deployments
• Feature Flag Changes
• Infrastructure Configurations
• GCP Events (e.g. host failure)

All times UTC.

2022-01-18

• 19:01 - First occurrences of the SQL error began appearing in Kibana (main stage)
• 19:25 - @bwill declares incident in Slack.
• 20:19 - Last occurrence of the SQL error occurred (main stage)
• 20:25 - all pods have been rotated

Takeaways

• We can restart k8s pods without noticeable downtime, without too many complications. See https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/14987 to have this procedure documented.

Corrective Actions

Corrective actions should be put here as soon as an incident is mitigated, ensure that all corrective actions mentioned in the notes below are included.

• https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/14987
• Create SLI / SLO for the autocomplete endpoints in the runbooks https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/15105

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Incident Review

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Customer Impact

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What were the root causes?

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Incident Response Analysis

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Post Incident Analysis

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Resources

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