support HTTP & GRPC protocol in sia otel instrumentation

[py4chen]

Description

This PR enables SIA users to specify http://<collector-endpoint>:<port> and grpc://<collector-endpoint>:<port> in the otel config.

Verification (HTTP)

• Ran an otel collector with the following config:

receivers:
  otlp:
    protocols:
      http:
        endpoint: 0.0.0.0:4318

• Execute the following go code to invoke the otel package:

func main() {
	cfg := config.OTel{
		CollectorEndpoint: otelColEndpoint,
		CACertPath:        caCertPath,
	}
	shutdownFn := myotel.StartOTelProvider(cfg)
	shutdownFlush := func() {
		shutdownCtx, cancel := context.WithTimeout(context.Background(), time.Second*2)
		if err := shutdownFn(shutdownCtx); err != nil {
			log.Printf("failed to shut down oTel provider: %v", err)
		}
		cancel()
	}
	defer shutdownFlush()

	meter := otel.GetMeterProvider().Meter("otel-sender")

	mGauge, err := meter.Int64Gauge(
		"my-gauge",
		metric.WithUnit("1"),
	)
	if err != nil {
		log.Printf("Error creating metric %v", err)
	}

	mGauge.Record(context.Background(), 123)

	fmt.Println("completed")
}

• can successfully find the metrics sent to the collector

InstrumentationScope otel-sender 
Metric #0
Descriptor:
     -> Name: my-gauge
     -> Description: 
     -> Unit: 1
     -> DataType: Gauge
NumberDataPoints #0
StartTimestamp: 2025-10-23 13:03:42.285714 +0000 UTC
Timestamp: 2025-10-23 13:03:42.285758 +0000 UTC
Value: 123
        {"resource": {"service.instance.id": "73a3927d-1807-4d86-b11c-3479d8a6c910", "service.name": "otelcol", "service.version": "0.137.0"}, "otelcol.component.id": "debug", "otelcol.component.kind": "exporter", "otelcol.signal": "metrics"}

Contribution Checklist:

• The pull request does not introduce any breaking changes
• I have read the contribution guidelines.
• Create an issue and link to the pull request.

Attach Screenshots (Optional)

[havetisyan]

/gemini review

[gemini-code-assist]

Code Review

This pull request adds support for both HTTP and gRPC protocols for the OpenTelemetry collector endpoint, allowing users to specify the protocol in the endpoint URL. The changes are well-structured, introducing protocol detection logic and conditional exporter creation for gRPC and HTTP. Comprehensive tests for HTTP, HTTPS, and gRPC have been added, which is excellent. I have a few suggestions to improve the robustness of the protocol detection logic and to align error handling with common Go practices. Overall, this is a valuable enhancement to the SIA OTEL instrumentation.

[py4chen]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces support for HTTP and gRPC protocols in the SIA OTel instrumentation. It includes changes to go.mod, go.sum, config.go, and introduces new files for metric sending and utility functions. The changes allow users to specify collector endpoints with HTTP/HTTPS/GRPC schemes. I have provided review comments to address potential issues and improve the code.

[py4chen]

/gemini review

[gemini-code-assist]

Code Review

This pull request adds support for both HTTP and gRPC protocols for OpenTelemetry metric exporting. The changes include adding the gRPC OTLP exporter dependency, refactoring the metric sender to dynamically choose the exporter based on the collector endpoint URL, and adding utility functions for protocol detection. The implementation is supported by a comprehensive set of new unit tests for HTTP, HTTPS, and gRPC scenarios.

My review focuses on the robustness of the new protocol detection logic. I've identified a potential issue in the isGRPCProtocol utility function that could lead to incorrect protocol detection in some edge cases and have suggested a more robust implementation. I've also recommended adding more test cases to cover these edge cases. Overall, this is a great addition that increases the flexibility of the OTel instrumentation.