Spring Boot Observability

Production observability with Actuator endpoints, Micrometer metrics, and OpenTelemetry tracing.

Core Components

| Component | Purpose | |-----------|---------| | Actuator | Health checks, info, metrics exposure, operational endpoints | | Micrometer | Metrics abstraction (Timer, Counter, Gauge, DistributionSummary) | | OpenTelemetry | Distributed tracing (default in Spring Boot 4) |

Core Workflow

1. Add starters → actuator, micrometer-registry-*, opentelemetry
2. Configure endpoint exposure → Secure sensitive endpoints
3. Define health groups → Separate liveness from readiness
4. Add custom metrics → Business-specific measurements
5. Configure tracing → Sampling, propagation, export

Quick Patterns

See EXAMPLES.md for complete working examples including:

• Production Actuator Configuration with health groups and Kubernetes probes
• Custom Health Indicator with latency monitoring (Java + Kotlin)
• Custom Micrometer Metrics with Counter, Timer, and Gauge patterns
• OpenTelemetry Span Customization with Observation API
• OpenTelemetry Configuration for OTLP export
• Actuator Endpoint Access Control (Boot 4)

Spring Boot 4 Specifics

• OpenTelemetry is the default tracer (replaces Brave)
• Health Indicator imports from org.springframework.boot.health.contributor.*
• Endpoint Access Control with access: none/unrestricted/read-only

Detailed References

• Examples: See EXAMPLES.md for complete working code examples
• Troubleshooting: See TROUBLESHOOTING.md for common issues and Boot 4 migration
• Actuator Endpoints: See references/ACTUATOR.md for endpoint configuration, security, custom endpoints
• Micrometer Metrics: See references/METRICS.md for Timer, Counter, Gauge, DistributionSummary patterns
• Distributed Tracing: See references/TRACING.md for OpenTelemetry, span customization, context propagation

Anti-Pattern Checklist

| Anti-Pattern | Fix | |--------------|-----| | DB checks in liveness probe | Move to readiness group only | | 100% trace sampling in production | Use 10% or less | | Exposing all endpoints publicly | Separate management port + auth | | High-cardinality metric tags | Use low-cardinality tags only | | Missing graceful shutdown | Add server.shutdown=graceful | | No health probe groups | Separate liveness and readiness |

Related Skills

| Need | Skill | |------|-------| | Dependency validation | spring-boot-verify | | Actuator security | spring-boot-security | | Actuator testing | spring-boot-testing | | Module metrics | spring-boot-modulith |

Critical Reminders

1. Separate liveness from readiness — Liveness: "is process alive?", Readiness: "can handle traffic?"
2. Low cardinality tags only — User IDs, request IDs = bad; status codes, regions = good
3. Secure Actuator endpoints — Use separate port or authentication
4. Sample traces in production — 100% sampling overwhelms collectors
5. Graceful shutdown — Allow in-flight requests to complete