Resolves #242

Summary

This PR updates the OpenTelemetry SDK dependency from version 1.38.0 to 1.40.0 as requested in issue #242.

Changes Made

• Updated go.opentelemetry.io/otel from v1.38.0 to v1.40.0
• Updated go.opentelemetry.io/otel/metric from v1.38.0 to v1.40.0
• Updated go.opentelemetry.io/otel/sdk from v1.38.0 to v1.40.0
• Updated go.opentelemetry.io/otel/sdk/metric from v1.38.0 to v1.40.0
• Updated go.opentelemetry.io/otel/trace from v1.38.0 to v1.40.0

Changelog Highlights (from 1.38.0 to 1.40.0)

Added

• AlwaysRecord sampler in go.opentelemetry.io/otel/sdk/trace
• Enabled method to all synchronous instrument interfaces
• go.opentelemetry.io/otel/semconv/v1.39.0 package

Changed

• Improved concurrent performance of various components (4x improvement for HistogramReservoir)
• Various performance improvements for histogram measurements, gauge measurements, and exponential histogram measurements

Fixed

• Various bug fixes in logging, attribute handling, and HTTP/2 GOAWAY frame handling

Deprecated

• go.opentelemetry.io/otel/exporters/zipkin (not used in this codebase)

Code Analysis

The update appears to be safe for this codebase:

1. The code doesn't use any deprecated features (like Zipkin exporter)
2. The code doesn't use the new APIs that were added
3. The changes are primarily additive and performance improvements
4. No breaking changes that affect the current OpenTelemetry usage patterns in the code

Testing

• Manual code review of OpenTelemetry usage in:
  • otel/otel.go - Metrics collection implementation
  • api/middlewares/telemetry.go - Telemetry middleware
  • cmd/gateway/main.go - OpenTelemetry initialization
• The go.mod file has been updated with the new versions

Note

The go.opentelemetry.io/otel/exporters/prometheus dependency remains at v0.60.0 as it follows a separate versioning scheme and doesn't need to be updated for compatibility.