Monitoring

Complexity Levels

| Level | Tools | Setup Time | Best For | |-------|-------|------------|----------| | Minimal | UptimeRobot, Healthchecks.io | 15 min | Side projects, MVPs | | Standard | Uptime Kuma, Sentry, basic Grafana | 1-2 hours | Small teams, startups | | Professional | Prometheus, Grafana, Loki, Alertmanager | 1-2 days | Production systems | | Enterprise | Datadog, New Relic, or full OSS stack | Ongoing | Large-scale operations |

The Three Pillars

| Pillar | What It Answers | Tools | |--------|-----------------|-------| | Metrics | "How is the system performing?" | Prometheus, Grafana, Datadog | | Logs | "What happened?" | Loki, ELK, CloudWatch | | Traces | "Why is this request slow?" | Jaeger, Tempo, Sentry |

Quick Start by Use Case

"I just want to know if it's down" → UptimeRobot (free) or Uptime Kuma (self-hosted). See simple.md.

"I need to debug production errors" → Sentry with your framework SDK. 5-minute setup. See apm.md.

"I want real observability" → Prometheus + Grafana + Loki. See prometheus.md.

"I need to centralize logs" → Loki for simple, ELK for complex queries. See logs.md.

What to Monitor

Applications (RED Method)

• Rate — requests per second
• Errors — error rate by endpoint
• Duration — latency (p50, p95, p99)

Infrastructure (USE Method)

• Utilization — CPU, memory, disk usage
• Saturation — queue depth, load average
• Errors — hardware/system errors

Alerting Principles

| Do | Don't | |----|-------| | Alert on symptoms (user impact) | Alert on causes (CPU high) | | Include runbook link | Require investigation to understand | | Set appropriate severity | Make everything P1 | | Require action | Alert on "interesting" metrics |

Alert fatigue kills monitoring. If alerts are ignored, you have no monitoring.

For alert configuration, severities, and on-call setup, see alerting.md.

Cost Comparison

| Solution | Monthly Cost (small) | Monthly Cost (medium) | |----------|---------------------|----------------------| | UptimeRobot | Free | $7 | | Uptime Kuma | $5 (VPS) | $5 (VPS) | | Sentry | Free / $26 | $80 | | Grafana Cloud | Free tier | $50+ | | Datadog | $15/host | $23/host + features | | Self-hosted stack | $10-20 (VPS) | $50-100 (VPS) |

Common Mistakes

• Starting with Prometheus/Grafana when Uptime Kuma would suffice
• No alerting (dashboards nobody watches)
• Too many alerts (alert fatigue → ignored)
• Missing runbooks (alert fires, nobody knows what to do)
• Not monitoring from outside (only internal checks)
• Storing logs forever (cost explodes)