Incidents/2022-08-16 Beta Cluster 502

From Wikitech

document status: draft

Summary

Incident metadata (see Incident Scorecard)
Incident ID 2022-08-16 Beta Cluster 502 Start 2022-08-16 17:57:00
Task T315350 End 2022-08-17 00:57:00
People paged 0 Responder count 8
Coordinators TheresNoTime Affected metrics/SLOs beta has a best effort SLA
Impact For 7 hours, all Beta Cluster sites were unavailable. This also affected daily Selenium test jobs.

After an inadvertent restart of some WMCS cloudvirts and their associated VMs, all sites within the Beta Cluster (e.g. https://meta.wikimedia.beta.wmflabs.org/wiki/Main_Page) failed to load, with Error: 502, Next Hop Connection Failed — this persisted post-restart of the relevant VMs.

Drafting: possibly an apache config/puppet failure (https://phabricator.wikimedia.org/T315350#8159826), restarting trafficserver seems to have fixed it (https://phabricator.wikimedia.org/T315350#8159954)

The incident was complicated by the lack of Beta Cluster's maintenance meaning ongoing "normal" errors distracted from the cause.

Timeline

All times in UTC.

  • 2022-08-16 17:57 OUTAGE BEGINS: Uptime monitoring "pages" TheresNoTime, who informs #wikimedia-operations & #wikimedia-releng
    • This coincides with the WMCS VM accidental restarts ([Cloud] [Cloud-announce] Some cloud-vps servers just rebooted)
  • 2022-08-16 18:21 T315350 logged
  • 2022-08-17 00:57 OUTAGE ENDS

Detection

Conclusions

What went well?

  • A number of volunteers were available to triage

What went poorly?

  • no paging/alerting surfaced on IRC, so minimal initial visibility
  • lack of fast response from people with sufficient knowledge
  • beta is already broken in weird and wonderful ways

Where did we get lucky?

  • No deployments were affected
  • Beta wasn't needed due to test/replicate production issues during the time.

(Use bullet points) for example: user's error report was exceptionally detailed, incident occurred when the most people were online to assist, etc

How many people were involved in the remediation?

  • 3 Volunteers
  • 2 Release Engineers
  • 2 SRE - 1 Search Platform, 1 ServiceOps
  • 1 WMCS admin


(Use bullet points) for example: 2 SREs and 1 software engineer troubleshooting the issue plus 1 incident commander

Links to relevant documentation

  • …

Add links to information that someone responding to this alert should have (runbook, plus supporting docs). If that documentation does not exist, add an action item to create it.

Actionables

Create a list of action items that will help prevent this from happening again as much as possible. Link to or create a Phabricator task for every step.

Add the #Sustainability (Incident Followup) and the #SRE-OnFIRE (Pending Review & Scorecard) Phabricator tag to these tasks.

Scorecard

Incident Engagement ScoreCard
Question Answer

(yes/no)

Notes
People Were the people responding to this incident sufficiently different than the previous five incidents? no
Were the people who responded prepared enough to respond effectively no
Were fewer than five people paged? yes
Were pages routed to the correct sub-team(s)? no
Were pages routed to online (business hours) engineers? Answer “no” if engineers were paged after business hours. yes
Process Was the incident status section actively updated during the incident? no
Was the public status page updated? no
Is there a phabricator task for the incident? yes
Are the documented action items assigned? no
Is this incident sufficiently different from earlier incidents so as not to be a repeat occurrence? yes
Tooling To the best of your knowledge was the open task queue free of any tasks that would have prevented this incident? Answer “no” if there are

open tasks that would prevent this incident or make mitigation easier if implemented.

no
Were the people responding able to communicate effectively during the incident with the existing tooling? yes
Did existing monitoring notify the initial responders? no
Were the engineering tools that were to be used during the incident, available and in service? no
Were the steps taken to mitigate guided by an existing runbook? no
Total score (count of all “yes” answers above) 5
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