can create matric in there respective module.

pkg/plugin/implementation/otelmetrics/metrics.go

@@ -0,0 +1,97 @@
+package otelmetrics
+
+import (
+	"context"
+	"fmt"
+	"sync"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/metric"
+)
+
+// HTTPMetrics exposes HTTP-related metric instruments.
+type HTTPMetrics struct {
+	HTTPRequestsTotal    metric.Int64Counter
+	HTTPRequestDuration  metric.Float64Histogram
+	HTTPRequestsInFlight metric.Int64UpDownCounter
+	HTTPRequestSize      metric.Int64Histogram
+	HTTPResponseSize     metric.Int64Histogram
+	BecknMessagesTotal   metric.Int64Counter
+}
+
+var (
+	httpMetricsInstance *HTTPMetrics
+	httpMetricsOnce     sync.Once
+	httpMetricsErr      error
+)
+
+// GetHTTPMetrics lazily initializes HTTP metric instruments and returns a cached reference.
+func GetHTTPMetrics(ctx context.Context) (*HTTPMetrics, error) {
+	httpMetricsOnce.Do(func() {
+		httpMetricsInstance, httpMetricsErr = newHTTPMetrics()
+	})
+	return httpMetricsInstance, httpMetricsErr
+}
+
+func newHTTPMetrics() (*HTTPMetrics, error) {
+	meter := otel.GetMeterProvider().Meter(
+		"github.com/beckn-one/beckn-onix/otelmetrics",
+		metric.WithInstrumentationVersion("1.0.0"),
+	)
+
+	m := &HTTPMetrics{}
+	var err error
+
+	if m.HTTPRequestsTotal, err = meter.Int64Counter(
+		"http_server_requests_total",
+		metric.WithDescription("Total number of HTTP requests processed"),
+		metric.WithUnit("{request}"),
+	); err != nil {
+		return nil, fmt.Errorf("http_server_requests_total: %w", err)
+	}
+
+	if m.HTTPRequestDuration, err = meter.Float64Histogram(
+		"http_server_request_duration_seconds",
+		metric.WithDescription("HTTP request duration in seconds"),
+		metric.WithUnit("s"),
+		metric.WithExplicitBucketBoundaries(0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10),
+	); err != nil {
+		return nil, fmt.Errorf("http_server_request_duration_seconds: %w", err)
+	}
+
+	if m.HTTPRequestsInFlight, err = meter.Int64UpDownCounter(
+		"http_server_requests_in_flight",
+		metric.WithDescription("Number of HTTP requests currently being processed"),
+		metric.WithUnit("{request}"),
+	); err != nil {
+		return nil, fmt.Errorf("http_server_requests_in_flight: %w", err)
+	}
+
+	if m.HTTPRequestSize, err = meter.Int64Histogram(
+		"http_server_request_size_bytes",
+		metric.WithDescription("Size of HTTP request payloads"),
+		metric.WithUnit("By"),
+		metric.WithExplicitBucketBoundaries(100, 1000, 10000, 100000, 1000000),
+	); err != nil {
+		return nil, fmt.Errorf("http_server_request_size_bytes: %w", err)
+	}
+
+	if m.HTTPResponseSize, err = meter.Int64Histogram(
+		"http_server_response_size_bytes",
+		metric.WithDescription("Size of HTTP responses"),
+		metric.WithUnit("By"),
+		metric.WithExplicitBucketBoundaries(100, 1000, 10000, 100000, 1000000),
+	); err != nil {
+		return nil, fmt.Errorf("http_server_response_size_bytes: %w", err)
+	}
+
+	if m.BecknMessagesTotal, err = meter.Int64Counter(
+		"beckn_messages_total",
+		metric.WithDescription("Total Beckn protocol messages processed"),
+		metric.WithUnit("{message}"),
+	); err != nil {
+		return nil, fmt.Errorf("beckn_messages_total: %w", err)
+	}
+
+	return m, nil
+}