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Update README and add feature summary documentation
Co-authored-by: rootfs <[email protected]>
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‎README.md‎

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Cache the semantic representation of the prompt so as to reduce the number of prompt tokens and improve the overall inference latency.
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### Distributed Tracing 🔍
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Comprehensive observability with OpenTelemetry distributed tracing provides fine-grained visibility into the request processing pipeline:
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- **Request Flow Tracing**: Track requests through classification, security checks, caching, and routing
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- **Performance Analysis**: Identify bottlenecks with detailed timing for each operation
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- **Security Monitoring**: Trace PII detection and jailbreak prevention operations
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- **Routing Decisions**: Understand why specific models were selected
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- **OpenTelemetry Standard**: Industry-standard tracing with support for Jaeger, Tempo, and other OTLP backends
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See [Distributed Tracing Guide](https://vllm-semantic-router.com/docs/tutorials/observability/distributed-tracing/) for complete setup instructions.
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## Documentation 📖
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For comprehensive documentation including detailed setup instructions, architecture guides, and API references, visit:
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- **[System Architecture](https://vllm-semantic-router.com/docs/overview/architecture/system-architecture/)** - Technical deep dive
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- **[Model Training](https://vllm-semantic-router.com/docs/training/training-overview/)** - How classification models work
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- **[API Reference](https://vllm-semantic-router.com/docs/api/router/)** - Complete API documentation
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- **[Distributed Tracing](https://vllm-semantic-router.com/docs/tutorials/observability/distributed-tracing/)** - Observability and debugging guide
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## Community 👋
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‎TRACING_FEATURE.md‎

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# Distributed Tracing Feature Summary
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## Overview
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This feature implements comprehensive distributed tracing support for vLLM Semantic Router using OpenTelemetry, providing enterprise-grade observability for the request processing pipeline.
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## Implementation Details
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### Components Added
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#### 1. Core Tracing Infrastructure (`pkg/observability/`)
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- **tracing.go**: OpenTelemetry SDK integration
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- Tracer provider initialization with OTLP and stdout exporters
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- Configurable sampling strategies (always_on, always_off, probabilistic)
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- Graceful shutdown handling
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- Resource attributes with service metadata
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- **propagation.go**: W3C Trace Context propagation
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- Header injection for upstream requests
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- Header extraction from incoming requests
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- Context management utilities
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- **tracing_test.go**: Comprehensive unit tests
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- Configuration validation
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- Span creation and attribute setting
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- Context propagation
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- Error recording
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#### 2. Configuration (`pkg/config/`)
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- Extended RouterConfig with ObservabilityConfig
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- TracingConfig structure with exporter, sampling, and resource settings
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- Environment-specific configuration examples
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#### 3. Instrumentation (`pkg/extproc/`)
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- Request headers span with trace context extraction
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- Classification operation spans with timing
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- PII detection spans with detection results
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- Jailbreak detection spans with security actions
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- Cache lookup spans with hit/miss status
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- Routing decision spans with model selection reasoning
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- Backend selection spans with endpoint information
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- System prompt injection spans
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### Span Hierarchy
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```
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semantic_router.request.received (root)
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├─ semantic_router.classification
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├─ semantic_router.security.pii_detection
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├─ semantic_router.security.jailbreak_detection
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├─ semantic_router.cache.lookup
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├─ semantic_router.routing.decision
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├─ semantic_router.backend.selection
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├─ semantic_router.system_prompt.injection
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└─ semantic_router.upstream.request
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```
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### Span Attributes
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Following OpenInference semantic conventions:
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**Request Metadata:**
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- `request.id`, `user.id`, `session.id`
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- `http.method`, `http.path`
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**Model Information:**
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- `model.name`, `model.provider`, `model.version`
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- `routing.original_model`, `routing.selected_model`
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**Classification:**
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- `category.name`, `category.confidence`
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- `classifier.type`, `classification.time_ms`
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**Security:**
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- `pii.detected`, `pii.types`, `pii.detection_time_ms`
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- `jailbreak.detected`, `jailbreak.type`, `security.action`
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**Routing:**
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- `routing.strategy`, `routing.reason`
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- `reasoning.enabled`, `reasoning.effort`, `reasoning.family`
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**Performance:**
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- `cache.hit`, `cache.lookup_time_ms`
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- `processing.time_ms`
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## Configuration
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### Minimal (Development)
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```yaml
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observability:
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tracing:
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enabled: true
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exporter:
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type: "stdout"
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sampling:
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type: "always_on"
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resource:
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service_name: "vllm-semantic-router"
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```
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### Production (OTLP)
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```yaml
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observability:
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tracing:
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enabled: true
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exporter:
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type: "otlp"
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endpoint: "jaeger:4317"
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insecure: false
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sampling:
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type: "probabilistic"
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rate: 0.1
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resource:
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service_name: "vllm-semantic-router"
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service_version: "v0.1.0"
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deployment_environment: "production"
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```
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## Performance Impact
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- **Always-on sampling**: ~1-2% latency increase
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- **10% probabilistic**: ~0.1-0.2% latency increase
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- **Async export**: No blocking on span export
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- **Batch processing**: Reduced network overhead
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## Integration Points
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### Current
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- HTTP/gRPC header propagation
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- Structured logging correlation
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- Prometheus metrics alignment
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### Future (vLLM Stack)
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- Trace context forwarding to vLLM backends
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- End-to-end latency tracking
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- Token-level timing correlation
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- Unified observability dashboard
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## Files Changed/Added
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### Core Implementation
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- `src/semantic-router/pkg/observability/tracing.go` (new)
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- `src/semantic-router/pkg/observability/propagation.go` (new)
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- `src/semantic-router/pkg/observability/tracing_test.go` (new)
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- `src/semantic-router/pkg/config/config.go` (modified)
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- `src/semantic-router/pkg/extproc/request_handler.go` (modified)
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- `src/semantic-router/cmd/main.go` (modified)
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### Dependencies
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- `src/semantic-router/go.mod` (updated)
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- `src/semantic-router/go.sum` (updated)
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### Configuration Examples
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- `config/config.yaml` (updated)
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- `config/config.production.yaml` (new)
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- `config/config.development.yaml` (new)
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### Documentation
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- `website/docs/tutorials/observability/distributed-tracing.md` (new)
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- `website/docs/tutorials/observability/tracing-quickstart.md` (new)
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- `README.md` (updated)
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### Deployment
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- `deploy/docker-compose.tracing.yaml` (new)
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- `deploy/tracing/README.md` (new)
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## Testing
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All tests pass with coverage:
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```bash
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cd src/semantic-router
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go test -v ./pkg/observability
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# PASS: All tracing tests
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```
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Test coverage includes:
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- Configuration validation
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- Span creation and lifecycle
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- Attribute setting
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- Error recording
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- Context propagation
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- Noop tracer fallback
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## Usage Examples
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### Enable stdout tracing
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```bash
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# Update config.yaml
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observability:
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tracing:
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enabled: true
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exporter:
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type: "stdout"
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# Start router
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./semantic-router --config config.yaml
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# Send request - traces printed to console
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```
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### Deploy with Jaeger
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```bash
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# Start Jaeger
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docker run -d -p 4317:4317 -p 16686:16686 \
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jaegertracing/all-in-one
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# Configure router for OTLP
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# Start router
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# View traces at http://localhost:16686
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```
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## Benefits
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1. **Enhanced Debugging**
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- Trace individual request flows
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- Identify failure points quickly
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- Understand complex routing logic
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2. **Performance Optimization**
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- Pinpoint bottlenecks with millisecond precision
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- Compare operation timings
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- Analyze cache effectiveness
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3. **Security Monitoring**
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- Track PII detection operations
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- Monitor jailbreak attempts
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- Audit security decisions
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4. **Production Readiness**
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- Industry-standard observability
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- Integration with existing tools
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- Minimal performance overhead
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## Next Steps
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1. **vLLM Integration**
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- Forward trace context to vLLM backends
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- Correlate router and engine spans
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- End-to-end latency tracking
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2. **Advanced Features**
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- Custom exporters (Datadog, New Relic)
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- Dynamic sampling rate adjustment
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- Trace-based alerting
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- SLO tracking
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3. **Visualization**
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- Pre-built Grafana dashboards
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- Trace-to-metrics correlation
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- Custom trace queries
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## References
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- [OpenTelemetry Documentation](https://opentelemetry.io/docs/)
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- [OpenInference Semantic Conventions](https://github.com/Arize-ai/openinference)
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- [Jaeger Documentation](https://www.jaegertracing.io/docs/)
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- [W3C Trace Context Specification](https://www.w3.org/TR/trace-context/)

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