A good postmortem should include:
- A brief summary
- A timeline of the event from discovery through investigation to resolution
- The primary cause of the event
- Impact and damage assessment
- A set of action items to fix the problem immediately
- A set of action items to prevent the even from happening again
- Lessons learned
See https://landing.google.com/sre/sre-book/chapters/postmortem-culture/ and https://landing.google.com/sre/sre-book/chapters/postmortem/.
See also: https://github.com/etsy/morgue