# iron_telemetry - Specification
**Module:** iron_telemetry
**Layer:** 2 (Foundation)
**Status:** Active
> **Specification Philosophy:** This specification focuses on architectural-level design and well-established knowledge. It describes what the module does and why, not implementation details or algorithms. Implementation constraints are minimal to allow flexibility. For detailed requirements, see spec/-archived_detailed_spec.md.
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## Responsibility
Unified logging infrastructure using tracing crate. Provides structured logging with spans, log levels, and context propagation across all Iron Cage modules.
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## Scope
**In Scope:**
- Structured logging with tracing
- Log levels (debug, info, warn, error)
- Span tracking for request tracing
- Context propagation across async boundaries
- Log output formatting
**Out of Scope:**
- Observability export to external systems (see docs/integration/004)
- Metrics collection (see iron_control_api)
- Dashboard visualization (see iron_dashboard)
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## Dependencies
**Required External:**
- tracing - Structured logging
- tracing-subscriber - Log output
**Optional:**
- None
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## Core Concepts
**Key Components:**
- **Logger:** Centralized logging interface
- **Span Tracker:** Request tracing with context
- **Formatter:** Human-readable log output
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## Integration Points
**Used by:**
- All modules - Logging infrastructure
**Foundation module:** Published to crates.io for shared use
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*For detailed configuration, see spec/-archived_detailed_spec.md*
*For observability backends, see docs/integration/004_observability_backends.md*