# Release Notes - v0.5.1

## Observability Enhancements

### OTLP Metrics Support
- **New `metrics/` package** - OpenTelemetry-native metrics with OTLP export support for structured metrics collection
- **Centralized OTLP configuration** - Refactored configuration to `internal/tracerconfig/` to eliminate code duplication across tracing, logging, and metrics
- **HTTP retry support** - Added consistent retry configuration for all HTTP OTLP exporters to improve reliability

### Enhanced Logging
- **Buffering exporter** - Added OTLP log buffering to queue logs until tracing configuration is available
- **TLS support for logs** - Client certificate authentication support for secure OTLP log export
- **Improved logfmt formatting** - Better structured output for log messages

### Tracing Improvements
- **HTTP retry support** - OTLP trace requests now automatically retry on failure when using HTTP transport

## Build System

### Version Package Enhancements
- **Unix epoch build time support** - Build time can now be injected as Unix timestamps (`$(date +%s)`) in addition to RFC3339 format
- **Simplified build commands** - Reduces complexity of ldflags injection while maintaining backward compatibility
- **Consistent output format** - All build times normalize to RFC3339 format regardless of input

## API Changes

### New Public Interfaces
- `metrics.NewMeterProvider()` - Create OTLP metrics provider with centralized configuration
- `metrics.Shutdown()` - Graceful shutdown for metrics exporters
- `internal/tracerconfig` - Shared OTLP configuration utilities (internal package)

### Dependencies
- Added explicit OpenTelemetry metrics dependencies to `go.mod`
- Updated tracing dependencies for retry support