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monitoring-expert

Provides end-to-end observability across logs, metrics, traces, alerting, and performance testing. Use when instrumenting services, setting alert strategy, or designing an observability stack.

personAuthor: jakexiaohubgithub

Monitoring Expert

Use this skill when

  • Setting up application monitoring
  • Implementing structured logging
  • Creating metrics and dashboards
  • Configuring alerting rules
  • Detecting release regressions against a captured pre-deploy baseline
  • Correlating metrics to traces, or mapping service dependencies
  • Implementing distributed tracing
  • Debugging production issues with observability
  • Performance testing and load testing
  • Application profiling and bottleneck analysis
  • Capacity planning and resource forecasting

Do not use this skill when

  • The request is only for a single vendor UI walkthrough with no implementation decisions
  • The system already has a finalized observability plan and only needs routine execution
  • The task is post-deploy smoke or synthetic checking of a deployed URL, not deciding what the service itself measures
  • The user wants unrelated security auditing or code review not tied to monitoring

Required inputs

  • Service overview (architecture, language/runtime, deployment model)
  • Current telemetry stack (if any) and constraints
  • Critical user journeys or business KPIs
  • Traffic profile and latency/error targets
  • Compliance or data handling constraints (PII, retention)

Workflow

  1. Scope goals - Confirm critical paths, SLIs/SLOs, and stakeholders.
    • Output: Monitoring goals and scope statement.
  2. Plan instrumentation - Define structured (JSON) logs, metrics, and traces to add, every signal carrying a request/trace ID for correlation and sensitive fields (passwords, tokens, PII) redacted; include a health check endpoint when the architecture does not already expose an equivalent.
    • Decision: If no tracing is feasible, prioritize logs + metrics with correlation IDs.
    • Decision: If both traces and metrics are collected, attach trace IDs as exemplars on latency histograms so a metric spike resolves to one concrete trace, and keep error/slow-path trace sampling high enough that an exemplar resolves to a stored trace rather than a dropped one (references/prometheus-metrics.md).
    • Output: Instrumentation backlog with owners and acceptance criteria.
  3. Select collection/storage - Choose agents, pipelines, retention, and cardinality limits.
    • Decision: If managed services are mandated, align to vendor-specific exporters and limits.
    • Output: Telemetry architecture and data flow summary.
  4. Design dashboards - Build RED/USE-based views covering business KPIs alongside technical signals, each dashboard named for its audience and the decision it serves.
    • Output: Dashboard spec (panels, queries, refresh, owners).
  5. Define alerting - Alert on critical-path symptoms and error budgets, never on every error; set thresholds, burn-rate alerts, and paging policies.
    • Decision: If alert volume is high, switch to error budget or anomaly alerts.
    • Decision: If releases must be validated after rollout, capture a pre-deploy baseline and alert on the delta from it alongside the absolute thresholds (references/alerting-rules.md).
    • Decision: If the service terminates TLS, signs tokens, or holds fixed-lifetime credentials, add expiry alerts with enough lead time to complete rotation.
    • Output: Alert policy and routing matrix, every alert carrying an owner and a runbook link.
  6. Performance & capacity - Plan load tests, profiling, and capacity models.
    • Output: Test plan, profiling targets, and capacity assumptions.
  7. Verify & roll out - Emit a test request and require its correlated log, metric, and trace to all appear; exercise each alert route and treat a failure to page the declared owner as a rollout blocker.
    • Output: Verification checklist and operational handoff notes.

Resources

Load detailed guidance based on context:

| Topic | Reference | Load When | |-------|-----------|-----------| | Logging | references/structured-logging.md | Pino, JSON logging | | Metrics | references/prometheus-metrics.md | Counter, Histogram, Gauge, exemplars | | Tracing | references/opentelemetry.md | OpenTelemetry, spans | | Alerting | references/alerting-rules.md | Prometheus alerts, baseline regressions, expiry | | Dashboards | references/dashboards.md | RED/USE method, Grafana, topology | | Performance Testing (k6) | references/performance-testing-k6.md | Load test types, k6 stages | | Performance Testing (tools) | references/performance-testing-tools.md | Artillery, Locust, JMeter | | Performance Testing (scenarios) | references/performance-testing-scenarios-metrics.md | Metrics, user journeys | | Profiling (Node/Python) | references/application-profiling-node-python.md | CPU/memory profiling | | Profiling (Go/Java) | references/application-profiling-go-java.md | pprof, async-profiler | | Profiling (databases) | references/application-profiling-database.md | Query profiling | | Profiling (APM) | references/application-profiling-apm.md | Custom spans, vendor hooks | | Profiling (quick reference) | references/application-profiling-quick-reference.md | Tooling summary | | Capacity Planning (forecasting) | references/capacity-planning-forecasting.md | Trends, predict_linear | | Capacity Planning (resource models) | references/capacity-planning-resource-models.md | CPU, memory, connections | | Capacity Planning (scaling) | references/capacity-planning-scaling.md | Autoscaling patterns | | Capacity Planning (budgets/costs) | references/capacity-planning-budgets-costs.md | Budgets, sizing | | Capacity Planning (alerts/reference) | references/capacity-planning-alerts-reference.md | Alerts, heuristics | | Strategy | references/observability-strategy.md | End-to-end observability planning |

Examples

Example 1: Instrumentation plan

Input: “Add observability to our Node.js API and define alerts for latency.”

Output:

  • Goals: 95th percentile latency < 400ms; error rate < 1%
  • Instrumentation: JSON logs with request_id, http.server.duration histogram with trace-ID exemplars, traces for /checkout
  • Alerting: 5m burn-rate alert on latency, error budget alert on 4xx/5xx, post-deploy alert on the delta from the captured pre-deploy baseline
  • Verification: one test request traced end to end — its log line, histogram observation, and trace all carry the same trace ID

Example 2: Performance testing

Input: “We need load tests to validate 2x traffic before launch.”

Output:

  • k6 scenario: ramp 50 → 200 VUs over 10m, steady for 15m
  • Targets: /search, /checkout, /login
  • Pass criteria: p95 < 500ms, error rate < 0.5%

Output contract

When executing this skill, respond with the following sections:

  • Summary: One-paragraph overview of the monitoring plan.
  • Assumptions & Inputs: Any inferred context or missing data.
  • Instrumentation Plan: Logs/metrics/traces to add, with owners.
  • Telemetry Architecture: Collection, storage, retention, limits.
  • Dashboards: Panel list and KPIs.
  • Alerting: Policies, thresholds, routing.
  • Performance & Capacity: Test plan and profiling targets.
  • Verification: Steps to confirm signals and alerting work.
  • Risks & Follow-ups: Gaps or decisions needed.

References

See references/README.md for the index of detailed playbooks.