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