Observability And Monitoring Architecture — AWS Solutions Architect Pro (SAP-C02)
CloudWatch vs X-Ray: Resource Health vs Request Causality
CloudWatch Metrics and X-Ray both instrument distributed systems, but they answer different questions. CloudWatch captures what happened at each individual resource: CPU, error counts, latency at a single endpoint. X-Ray captures why a distributed request was slow by correlating segments across service boundaries in a single trace. Intermittent latency in a microservices architecture that appears only on specific call paths is an X-Ray problem, not a CloudWatch Metrics problem. SAP-C02 questions include both as answer options; the X-Ray signal is a distributed call path and a latency symptom that cannot be isolated to a single resource through per-resource metrics alone.
What This Pattern Tests
The exam describes a diagnostic need and tests which observability tool applies. CloudWatch Metrics provides aggregated health data — CPU utilization, error counts, latency percentiles. CloudWatch Logs captures event-level detail — application errors, access logs, VPC Flow Logs. X-Ray provides distributed request tracing — traces a single request across API Gateway, Lambda, DynamoDB, SQS showing where time is spent. CloudWatch Contributor Insights identifies top talkers. CloudWatch Anomaly Detection spots unusual patterns. The trap is recommending metrics dashboards when the scenario requires tracing a specific slow request through a microservice chain.
Decision Axis
Diagnostic question determines the tool: "Is it healthy?" = Metrics. "What happened?" = Logs. "Where is it slow?" = X-Ray.
Associated Traps
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Decision Rules
Whether the fully managed observability stack (Amazon Managed Service for Prometheus + CloudWatch composite alarms with anomaly detection + AWS X-Ray) satisfies the sub-five-minute MTTD target at lower and sustainable operational overhead than a self-managed Prometheus deployment that a two-engineer team cannot maintain without introducing MTTD regression risk.
Whether the MTTD-under-five-minutes and low-operational-overhead constraints are jointly satisfied by AWS-managed observability services (CloudWatch Container Insights, Amazon Managed Service for Prometheus, AWS X-Ray) or by a self-managed Prometheus stack on EKS that meets the MTTD target but violates the operational ceiling by requiring scrape config ownership, retention tuning, and HA management.
Domain Coverage
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