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SRE practices: SLOs, incidents, redundancy / Stage 4 of 8

A runbook and the first ten minutes

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Step 7 of 7 · summary · 2 min

Summary

  • The first minutes of an incident follow the runbook: confirm the symptom, start the timeline, find the last change, bring the service back, check.
  • The service goes back to users first — by a rollback, a restart, a switch; the cause is looked for later, from the saved copy and the timeline.
  • What changed last shows in the sudo journal, in file modification times (ls -lt, find -newermt) and in the machine's journal for the minutes before the alert.
  • A timeline is “time event” lines in UTC from the first minute; the time of events before you comes from the logs.
  • The site at the start of the lesson went down with no failure in the application: deploy moved it to port 8001 while nginx stayed on 8000 — rolling the port back returned the site before anyone worked out the cause.
Ubuntu 24.04
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