2020-12-08: SLI of the gitaly service (`cny` stage) has an error rate violating SLO

Summary

More information will be added as we investigate the issue.

Timeline

Two spikes of error rates coming from cny gitaly service:

The first one starting around 16:04 and ending around 16:13. The second spike started around 16:59 and ended at around 17:10. Error rates affected gitlab-org/gitlab and GRPC calls were Canceled. CPU saturation was caused primarily by pack objects and upload pack.

All times UTC.

2020-12-08

16:33 - cindy declares incident in Slack.

Corrective Actions

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Incident Review

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Summary

1. Service(s) affected:
2. Team attribution:
3. Time to detection:
4. Minutes downtime or degradation:

Metrics

Customer Impact

1. Who was impacted by this incident? (i.e. external customers, internal customers)
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2. What was the customer experience during the incident? (i.e. preventing them from doing X, incorrect display of Y, ...)
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3. How many customers were affected?
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4. If a precise customer impact number is unknown, what is the estimated impact (number and ratio of failed requests, amount of traffic drop, ...)?
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What were the root causes?

"5 Whys"

Incident Response Analysis

1. How was the incident detected?
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2. How could detection time be improved?
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3. How was the root cause diagnosed?
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4. How could time to diagnosis be improved?
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5. How did we reach the point where we knew how to mitigate the impact?
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6. How could time to mitigation be improved?
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7. What went well?
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Post Incident Analysis

1. Did we have other events in the past with the same root cause?
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2. Do we have existing backlog items that would've prevented or greatly reduced the impact of this incident?
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3. Was this incident triggered by a change (deployment of code or change to infrastructure)? If yes, link the issue.
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Lessons Learned

Guidelines

• Blameless RCA Guideline

Resources

1. If the Situation Zoom room was utilised, recording will be automatically uploaded to Incident room Google Drive folder (private)

Incident Review Stakeholders