2020-06-22: Increased Sidekiq mailers error rate

/label incident IncidentActive

Summary

Increased Sidekiq mailers error rate

Mailers queue is growing and error rate is high. Sentry shows many Net::OpenTimeout errors: https://sentry.gitlab.net/gitlab/gitlabcom/issues/1612981/?query=is%3Aunresolved.

We are in this situation since months apparently but just started alerting on mailers sidekiq errors on Friday.

Timeline

All times UTC.

2020-06-22

  • 08:33 - mailers queue error rate alert in #alerts-general
  • 09:06 - hphilipps declares incident in Slack using /incident declare command.
  • 10:20 - nat_ports_per_vm increased from 1024 -> 1536
  • 11:00 nat_ports_per_vm increased again from 1536 -> 2048. The IP pool was scaled from 7 to 14 to accommodate this.

Click to expand or collapse the Incident Review section.

Incident Review

Summary

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

Metrics

Customer Impact

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

Incident Response Analysis

  1. How was the event detected?
  2. How could detection time be improved?
  3. How did we reach the point where we knew how to mitigate the impact?
  4. How could time to mitigation be improved?

Post Incident Analysis

  1. How was the root cause diagnosed?
  2. How could time to diagnosis be improved?
  3. Do we have an existing backlog item that would've prevented or greatly reduced the impact of this incident?
  4. Was this incident triggered by a change (deployment of code or change to infrastructure. If yes, have you linked the issue which represents the change?)?

5 Whys

Lessons Learned

Corrective Actions

Guidelines

Edited by Brent Newton