2022-02-01: Pages elevated error rates
Incident DRI
Current Status
Observing an increase on 500 errors on Pages (including docs.gitlab.com), which appear to have started around Jan 31 at 23:16
, and elevated to the point of paging on Feb 01 at 09:00
.
A few candidate sentry reports were highlighted with a link to recent changes in gitlab-pages, this was determined to be the root cause.
Summary for CMOC notice / Exec summary:
- Customer Impact: No user impact.
- Service Impact: ServicePages
Timeline
Recent Events (available internally only):
- Deployments
- Feature Flag Changes
- Infrastructure Configurations
- GCP Events (e.g. host failure)
All times UTC.
2022-02-01
-
09:01
-📟 Firing 1 - The server SLI of the web-pages service in regionus-east1
has an error rate violating SLO -
09:02
-📟 Firing 1 - The server SLI of the web-pages service (cny
stage) has an error rate violating SLO -
09:04
- @rehab declares incident in Slack. -
11:00
- Sentry reports identified. -
11:15
- pinging team members who performed commits around the time of the problematic deployment. -
12:20
- @vshushlin determines this is a come back of a previous issue -
12:25
- @reprazent and @vshushlin working together to revert the problematic commits. -
22:17
- Errors subsided following the deployment.
2022-02-02
-
09:15
- IncidentMitigated
Takeaways
- The incident has no user impact.
- The error budget for web-pages will continue to suffer until a revert is deployed.
- The incident is a re-occurrence, a corrective action is needed to prevent this from happening again.
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.
- Implement feature flags for pages gitlab-org/gitlab-pages#345
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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
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Who was impacted by this incident? (i.e. external customers, internal customers)
- ...
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What was the customer experience during the incident? (i.e. preventing them from doing X, incorrect display of Y, ...)
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How many customers were affected?
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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
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How was the incident detected?
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How could detection time be improved?
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How was the root cause diagnosed?
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How could time to diagnosis be improved?
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How did we reach the point where we knew how to mitigate the impact?
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How could time to mitigation be improved?
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What went well?
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Post Incident Analysis
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Did we have other events in the past with the same root cause?
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Do we have existing backlog items that would've prevented or greatly reduced the impact of this incident?
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Was this incident triggered by a change (deployment of code or change to infrastructure)? If yes, link the issue.
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What went well?
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Guidelines
Resources
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