add the feature for observability

pkg/metrics/requests.go

@@ -0,0 +1,200 @@
+package metrics
+
+import (
+	"context"
+	"net/http"
+	"strconv"
+	"time"
+
+	"go.opentelemetry.io/otel/attribute"
+	otelmetric "go.opentelemetry.io/otel/metric"
+)
+
+var (
+	// Inbound request metrics
+	inboundRequestsTotal         otelmetric.Int64Counter
+	inboundSignValidationTotal   otelmetric.Int64Counter
+	inboundSchemaValidationTotal otelmetric.Int64Counter
+
+	// Outbound request metrics
+	outboundRequestsTotal   otelmetric.Int64Counter
+	outboundRequests2XX     otelmetric.Int64Counter
+	outboundRequests4XX     otelmetric.Int64Counter
+	outboundRequests5XX     otelmetric.Int64Counter
+	outboundRequestDuration otelmetric.Float64Histogram
+)
+
+// InitRequestMetrics initializes request-related metrics instruments.
+func InitRequestMetrics() error {
+	if !IsEnabled() {
+		return nil
+	}
+
+	meter := GetMeter()
+	var err error
+
+	// Inbound request metrics
+	inboundRequestsTotal, err = meter.Int64Counter(
+		"beckn.inbound.requests.total",
+		otelmetric.WithDescription("Total number of inbound requests per host"),
+	)
+	if err != nil {
+		return err
+	}
+
+	inboundSignValidationTotal, err = meter.Int64Counter(
+		"beckn.inbound.sign_validation.total",
+		otelmetric.WithDescription("Total number of inbound requests with sign validation per host"),
+	)
+	if err != nil {
+		return err
+	}
+
+	inboundSchemaValidationTotal, err = meter.Int64Counter(
+		"beckn.inbound.schema_validation.total",
+		otelmetric.WithDescription("Total number of inbound requests with schema validation per host"),
+	)
+	if err != nil {
+		return err
+	}
+
+	// Outbound request metrics
+	outboundRequestsTotal, err = meter.Int64Counter(
+		"beckn.outbound.requests.total",
+		otelmetric.WithDescription("Total number of outbound requests per host"),
+	)
+	if err != nil {
+		return err
+	}
+
+	outboundRequests2XX, err = meter.Int64Counter(
+		"beckn.outbound.requests.2xx",
+		otelmetric.WithDescription("Total number of outbound requests with 2XX status code per host"),
+	)
+	if err != nil {
+		return err
+	}
+
+	outboundRequests4XX, err = meter.Int64Counter(
+		"beckn.outbound.requests.4xx",
+		otelmetric.WithDescription("Total number of outbound requests with 4XX status code per host"),
+	)
+	if err != nil {
+		return err
+	}
+
+	outboundRequests5XX, err = meter.Int64Counter(
+		"beckn.outbound.requests.5xx",
+		otelmetric.WithDescription("Total number of outbound requests with 5XX status code per host"),
+	)
+	if err != nil {
+		return err
+	}
+
+	// Outbound request duration histogram (for p99, p95, p75)
+	outboundRequestDuration, err = meter.Float64Histogram(
+		"beckn.outbound.request.duration",
+		otelmetric.WithDescription("Duration of outbound requests in milliseconds"),
+		otelmetric.WithUnit("ms"),
+	)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// RecordInboundRequest records an inbound request.
+func RecordInboundRequest(ctx context.Context, host string) {
+	if inboundRequestsTotal == nil {
+		return
+	}
+	inboundRequestsTotal.Add(ctx, 1, otelmetric.WithAttributes(
+		attribute.String("host", host),
+	))
+}
+
+// RecordInboundSignValidation records an inbound request with sign validation.
+func RecordInboundSignValidation(ctx context.Context, host string) {
+	if inboundSignValidationTotal == nil {
+		return
+	}
+	inboundSignValidationTotal.Add(ctx, 1, otelmetric.WithAttributes(
+		attribute.String("host", host),
+	))
+}
+
+// RecordInboundSchemaValidation records an inbound request with schema validation.
+func RecordInboundSchemaValidation(ctx context.Context, host string) {
+	if inboundSchemaValidationTotal == nil {
+		return
+	}
+	inboundSchemaValidationTotal.Add(ctx, 1, otelmetric.WithAttributes(
+		attribute.String("host", host),
+	))
+}
+
+// RecordOutboundRequest records an outbound request with status code and duration.
+func RecordOutboundRequest(ctx context.Context, host string, statusCode int, duration time.Duration) {
+	if outboundRequestsTotal == nil {
+		return
+	}
+
+	attrs := []attribute.KeyValue{
+		attribute.String("host", host),
+		attribute.String("status_code", strconv.Itoa(statusCode)),
+	}
+
+	// Record total
+	outboundRequestsTotal.Add(ctx, 1, otelmetric.WithAttributes(attrs...))
+
+	// Record by status code category
+	statusClass := statusCode / 100
+	switch statusClass {
+	case 2:
+		outboundRequests2XX.Add(ctx, 1, otelmetric.WithAttributes(attrs...))
+	case 4:
+		outboundRequests4XX.Add(ctx, 1, otelmetric.WithAttributes(attrs...))
+	case 5:
+		outboundRequests5XX.Add(ctx, 1, otelmetric.WithAttributes(attrs...))
+	}
+
+	// Record duration for percentile calculations (p99, p95, p75)
+	if outboundRequestDuration != nil {
+		outboundRequestDuration.Record(ctx, float64(duration.Milliseconds()), otelmetric.WithAttributes(attrs...))
+	}
+}
+
+// HTTPTransport wraps an http.RoundTripper to track outbound request metrics.
+type HTTPTransport struct {
+	Transport http.RoundTripper
+}
+
+// RoundTrip implements http.RoundTripper interface and tracks metrics.
+func (t *HTTPTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	start := time.Now()
+	host := req.URL.Host
+
+	resp, err := t.Transport.RoundTrip(req)
+
+	duration := time.Since(start)
+	statusCode := 0
+	if resp != nil {
+		statusCode = resp.StatusCode
+	} else if err != nil {
+		// Network error - treat as 5XX
+		statusCode = 500
+	}
+
+	RecordOutboundRequest(req.Context(), host, statusCode, duration)
+
+	return resp, err
+}
+
+// WrapHTTPTransport wraps an http.RoundTripper with metrics tracking.
+func WrapHTTPTransport(transport http.RoundTripper) http.RoundTripper {
+	if !IsEnabled() {
+		return transport
+	}
+	return &HTTPTransport{Transport: transport}
+}