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Incidents/2022-08-16 x2 databases replication breakage

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document status: draft

Summary

Incident metadata (see Incident Scorecard)
Incident ID 2022-08-16 x2 databases replication breakage Start YYYY-MM-DD hh:mm:ss
Task End YYYY-MM-DD hh:mm:ss
People paged Responder count
Coordinators Affected metrics/SLOs
Impact Who was affected and how? For user-facing outages: Estimate how many queries were lost, which regions were affected, or which types of clients (editors? readers? bots?), etc. Do not assume the reader knows what your service is or who uses it.

Summary of what happened, in one or two paragraphs. Avoid assuming deep knowledge of the systems here, and try to differentiate between proximate causes and root causes.

Timeline

Write a step by step outline of what happened to cause the incident, and how it was remedied. Include the lead-up to the incident, and any epilogue.

Consider including a graphs of the error rate or other surrogate.

Link to a specific offset in SAL using the SAL tool at https://sal.toolforge.org/ (example)

All times in UTC.

  • 00:00 (TODO) OUTAGE BEGINS
  • 00:04 (Something something)
  • 00:06 (Voila) OUTAGE ENDS
  • 00:15 (post-outage cleanup finished)

TODO: Clearly indicate when the user-visible outage began and ended.

Detection

Write how the issue was first detected. Was automated monitoring first to detect it? Or a human reporting an error?

Copy the relevant alerts that fired in this section.

Did the appropriate alert(s) fire? Was the alert volume manageable? Did they point to the problem with as much accuracy as possible?

TODO: If human only, an actionable should probably be to "add alerting".

Conclusions

What went well?


(Use bullet points) for example: automated monitoring detected the incident, outage was root-caused quickly, etc

What went poorly?

What weaknesses did we learn about and how can we address them? (Use bullet points) for example: documentation on the affected service was unhelpful, communication difficulties, etc

Where did we get lucky?

(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?


(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?
Were the people who responded prepared enough to respond effectively
Were fewer than five people paged?
Were pages routed to the correct sub-team(s)?
Were pages routed to online (business hours) engineers?  Answer “no” if engineers were paged after business hours.
Process Was the incident status section actively updated during the incident?
Was the public status page updated?
Is there a phabricator task for the incident?
Are the documented action items assigned?
Is this incident sufficiently different from earlier incidents so as not to be a repeat occurrence?
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.

Were the people responding able to communicate effectively during the incident with the existing tooling?
Did existing monitoring notify the initial responders?
Were the engineering tools that were to be used during the incident, available and in service?
Were the steps taken to mitigate guided by an existing runbook?
Total score (count of all “yes” answers above)