2021-09-15 The workhorse SLI of the api service violating SLO

Current Status

#5540 (closed) caused traffic to switch to canary (expectation was it would shift to the other zonal clusters). Canary has been drained while that activity completes.

Timeline

View recent production deployment and configuration events / gcp events (internal only)

All times UTC.

2021-09-15

  • 00:22 - us-east1-b set to maintenance mode in haproxy, front-end load balances in that zone switched their traffic to canary, saturating canary
  • 00:22-00:27 - canary scaled up from 16 nodes to 39 to absorb the load, and the starts trending up again.
  • 00:27 - first alert fires (apdex is below alerting thresholds
  • 00:31 - @cmiskell declares incident in Slack.
  • 00:32 - apdex is good again,
  • 00:37 - alerts start clearing
  • 00:48 - last alert clears.

Corrective Actions

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Incident Review
  • Ensure that the exec summary is completed at the top of the incident issue, the timeline is updated and relevant graphs are included in the summary
  • If there are any corrective action items mentioned in the notes on the incident, ensure they are listed in the "Corrective Action" section
  • Fill out relevant sections below or link to the meeting review notes that cover these topics

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?

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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

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Guidelines

Resources

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