Added external attributes option

otelginmetrics/config.go

@@ -1,16 +1,19 @@
 package otelginmetrics
 
 import (
+	"net/http"
+
 	"go.opentelemetry.io/otel/attribute"
+	semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
 )
 
 type config struct {
 	recordInFlight bool
 	recordSize     bool
 	recordDuration bool
 	groupedStatus  bool
-	attributes     []attribute.KeyValue
 	recorder       Recorder
+	attributes     func(serverName, route string, request *http.Request) []attribute.KeyValue
 }
 
 func defaultConfig() *config {
@@ -19,5 +22,20 @@ func defaultConfig() *config {
 		recordDuration: true,
 		recordSize:     true,
 		groupedStatus:  true,
+		attributes:     DefaultAttributes,
+	}
+}
+
+var DefaultAttributes = func(serverName, route string, request *http.Request) []attribute.KeyValue {
+	attrs := []attribute.KeyValue{
+		semconv.HTTPMethodKey.String(request.Method),
+	}
+
+	if serverName != "" {
+		attrs = append(attrs, semconv.HTTPServerNameKey.String(serverName))
+	}
+	if route != "" {
+		attrs = append(attrs, semconv.HTTPRouteKey.String(route))
 	}
+	return attrs
 }

otelginmetrics/example/main.go

@@ -110,7 +110,10 @@ func main() {
 	initMetrics()
 	router.Use(otelginmetrics.Middleware(
 		"TEST-SERVICE",
-		otelginmetrics.WithAdditionalAttributes(map[string]string{"label": "value"}),
+		// Custom attributes
+		otelginmetrics.WithAttributes(func(serverName, route string, request *http.Request) []attribute.KeyValue {
+			return append(otelginmetrics.DefaultAttributes(serverName, route, request), attribute.String("Custom-attribute", "value"))
+		}),
 	))
 
 	logic := func(ctx *gin.Context, sleep int) {

otelginmetrics/middleware.go

@@ -5,7 +5,6 @@ import (
 	"time"
 
 	"github.com/gin-gonic/gin"
-	"go.opentelemetry.io/otel/attribute"
 	semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
 )
 
@@ -32,7 +31,7 @@ func Middleware(service string, options ...Option) gin.HandlerFunc {
 
 		start := time.Now()
 
-		reqAttributes := append(cfg.attributes, getRequestAttributes(service, route, ginCtx.Request)...)
+		reqAttributes := cfg.attributes(service, route, ginCtx.Request)
 
 		if cfg.recordInFlight {
 			recorder.AddInflightRequests(ctx, 1, reqAttributes)
@@ -67,27 +66,6 @@ func Middleware(service string, options ...Option) gin.HandlerFunc {
 	}
 }
 
-func getRequestAttributes(serverName, route string, request *http.Request) []attribute.KeyValue {
-	attrs := []attribute.KeyValue{
-		semconv.HTTPMethodKey.String(request.Method),
-		semconv.HTTPTargetKey.String(request.RequestURI),
-	}
-
-	if serverName != "" {
-		attrs = append(attrs, semconv.HTTPServerNameKey.String(serverName))
-	}
-	if route != "" {
-		attrs = append(attrs, semconv.HTTPRouteKey.String(route))
-	}
-	if ua := request.UserAgent(); ua != "" {
-		attrs = append(attrs, semconv.HTTPUserAgentKey.String(ua))
-	}
-	if request.Host != "" {
-		attrs = append(attrs, semconv.HTTPHostKey.String(request.Host))
-	}
-	return attrs
-}
-
 func computeApproximateRequestSize(r *http.Request) int64 {
 	s := 0
 	if r.URL != nil {

otelginmetrics/option.go

@@ -1,6 +1,8 @@
 package otelginmetrics
 
 import (
+	"net/http"
+
 	"go.opentelemetry.io/otel/attribute"
 )
 
@@ -15,14 +17,11 @@ func (fn optionFunc) apply(cfg *config) {
 	fn(cfg)
 }
 
-// WithAdditionalAttributes sets a list of attribute.KeyValue labels for all metrics associated with this round tripper
-func WithAdditionalAttributes(attributes map[string]string) Option {
+// WithAttributes sets a func using which what attributes to be recorded can be specified.
+// By default the DefaultAttributes is used
+func WithAttributes(attributes func(serverName, route string, request *http.Request) []attribute.KeyValue) Option {
 	return optionFunc(func(cfg *config) {
-		attr := make([]attribute.KeyValue, 0, len(attributes))
-		for k, v := range attributes {
-			attr = append(attr, attribute.String(k, v))
-		}
-		cfg.attributes = attr
+		cfg.attributes = attributes
 	})
 }