Operating Production Services

Production reliability patterns: measure what matters, learn from failures, improve systematically.

Quick Reference

| Need | Go To | |------|-------| | Define reliability targets | SLOs & Error Budgets | | Write incident report | Postmortem Templates | | Set up SLO alerting | references/slo-alerting.md |

SLOs & Error Budgets

The Hierarchy

SLA (Contract) → SLO (Target) → SLI (Measurement)

Common SLIs

promql
# Availability: successful requests / total requests
sum(rate(http_requests_total{status!~"5.."}[28d]))
/
sum(rate(http_requests_total[28d]))

# Latency: requests below threshold / total requests
sum(rate(http_request_duration_seconds_bucket{le="0.5"}[28d]))
/
sum(rate(http_request_duration_seconds_count[28d]))

SLO Targets Reality Check

| SLO % | Downtime/Month | Downtime/Year | |-------|----------------|---------------| | 99% | 7.2 hours | 3.65 days | | 99.9% | 43 minutes | 8.76 hours | | 99.95% | 22 minutes | 4.38 hours | | 99.99% | 4.3 minutes | 52 minutes |

Don't aim for 100%. Each nine costs exponentially more.

Error Budget

Error Budget = 1 - SLO Target

Example: 99.9% SLO = 0.1% error budget = 43 minutes/month

Policy: | Budget Remaining | Action | |------------------|--------| | > 50% | Normal velocity | | 10-50% | Postpone risky changes | | < 10% | Freeze non-critical changes | | 0% | Feature freeze, fix reliability |

See references/slo-alerting.md for Prometheus recording rules and multi-window burn rate alerts.

Postmortem Templates

The Blameless Principle

| Blame-Focused | Blameless | |---------------|-----------| | "Who caused this?" | "What conditions allowed this?" | | Punish individuals | Improve systems | | Hide information | Share learnings |

When to Write Postmortems

• SEV1/SEV2 incidents
• Customer-facing outages > 15 minutes
• Data loss or security incidents
• Near-misses that could have been severe
• Novel failure modes

Standard Template

markdown
# Postmortem: [Incident Title]

**Date**: YYYY-MM-DD | **Duration**: X min | **Severity**: SEVX

## Executive Summary
One paragraph: what happened, impact, root cause, resolution.

## Timeline (UTC)
| Time | Event |
|------|-------|
| HH:MM | First alert fired |
| HH:MM | On-call acknowledged |
| HH:MM | Root cause identified |
| HH:MM | Fix deployed |
| HH:MM | Service recovered |

## Root Cause Analysis

### 5 Whys
1. Why did service fail? → [Answer]
2. Why did [1] happen? → [Answer]
3. Why did [2] happen? → [Answer]
4. Why did [3] happen? → [Answer]
5. Why did [4] happen? → [Root cause]

## Impact
- Customers affected: X
- Duration: X minutes
- Revenue impact: $X
- Support tickets: X

## Action Items
| Priority | Action | Owner | Due | Ticket |
|----------|--------|-------|-----|--------|
| P0 | [Immediate fix] | @name | Date | XXX-123 |
| P1 | [Prevent recurrence] | @name | Date | XXX-124 |
| P2 | [Improve detection] | @name | Date | XXX-125 |

Quick Template (Minor Incidents)

markdown
# Quick Postmortem: [Title]

**Date**: YYYY-MM-DD | **Duration**: X min | **Severity**: SEV3

## What Happened
One sentence description.

## Timeline
- HH:MM - Trigger
- HH:MM - Detection
- HH:MM - Resolution

## Root Cause
One sentence.

## Fix
- Immediate: [What was done]
- Long-term: [Ticket XXX-123]

Postmortem Meeting Guide

Structure (60 min)

1. Opening (5 min) - Remind: "We're here to learn, not blame"
2. Timeline (15 min) - Walk through events chronologically
3. Analysis (20 min) - What failed? Why? What allowed it?
4. Action Items (15 min) - Prioritize, assign owners, set dates
5. Closing (5 min) - Summarize learnings, confirm owners

Facilitation Tips

• Redirect blame to systems: "What made this mistake possible?"
• Time-box tangents
• Document dissenting views
• Encourage quiet participants

Anti-Patterns

| Don't | Do Instead | |-------|------------| | Aim for 100% SLO | Accept error budget exists | | Skip small incidents | Small incidents reveal patterns | | Orphan action items | Every item needs owner + date + ticket | | Blame individuals | Ask "what conditions allowed this?" | | Create busywork actions | Actions should prevent recurrence |

Verification

Run: python scripts/verify.py

References

• references/slo-alerting.md - Prometheus rules, burn rate alerts, Grafana dashboards