2021-04-24 The rails_primary_sql SLI of the patroni service (`main` stage) has an apdex violating SLO

Current Status

Enabling load-balancing on sidekiq has resulted in a new source of metrics for SQL apdex, and these queries can be (acceptably) slower/longer than those in web + API, affecting the apdex unhelpfully.

The metrics catalog will likely need an update, but this requires some discussion/more eyes. The alert has been silenced/resolved for the weekend.

The increase in RPS metric on the primary DB is not an increase in actual RPS, it's just that we're counting many now that we weren't before.

Timeline

View recent production deployment and configuration events (internal only)

All times UTC.

2021-04-24

  • 01:23 - Apdex alert fires
  • 01:58 - @cmiskell declares incident in Slack.
  • 02:39 - Canary drained; most recent canary release suspected of changing something
  • 02:43 - Alert clears, but not because of the canary draining (more to come)
  • 02:52 - Canary re-enabled
  • 03:07 - Apdex alert fires again.
  • 03:42 - Alert clears
  • 04:05 - Silence added

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.

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Click to expand or collapse the Incident Review section.

Incident Review

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)
    1. ...
  2. What was the customer experience during the incident? (i.e. preventing them from doing X, incorrect display of Y, ...)
    1. ...
  3. How many customers were affected?
    1. ...
  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?
    1. ...
  2. How could detection time be improved?
    1. ...
  3. How was the root cause diagnosed?
    1. ...
  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?
    1. ...
  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 Craig Miskell