4.2.1 Logging vs Monitoring vs Observability
Differences Between Logging, Monitoring, and Observability
| Logging | Monitoring | Observability |
|---|
| What | Record events/actions | Track metrics over time | Understand system state |
| When | Reactive (after issue) | Proactive (detect issues) | Both |
| Tools | CloudWatch Logs | CloudWatch Metrics/Alarms | Logs + Metrics + Traces |
| Question | “What happened?” | “Is it working?” | “Why is this happening?” |
Three Pillars of Observability
1. Logs → What happened (detailed events)
2. Metrics → How is it performing (numbers over time)
3. Traces → Where is the bottleneck (request flow)
| Pillar | AWS Service | Mô tả |
|---|
| Logs | CloudWatch Logs | Application events, errors |
| Metrics | CloudWatch Metrics | Latency, error rate, throughput |
| Traces | X-Ray | End-to-end request path |
Exam Tip: Observability = Logs + Metrics + Traces combined. Logging = reactive. Monitoring = proactive. Observability = understand WHY issues happen.