Added possibility to customize span operationName

Extended TracerConfig with OperationNameFunc which allows
to override default operation name during span creation.

If there is no OperationNameFunc provided then fallback
will be used which covers most of the use-cases.

Author: m1x0n

jaegertracing/jaegertracing.go

@@ -62,6 +62,9 @@ type (
 		// http body limit size (in bytes)
 		// NOTE: don't specify values larger than 60000 as jaeger can't handle values in span.LogKV larger than 60000 bytes
 		LimitSize int
+
+		// OperationNameFunc composes operation name based on context. Can be used to override default naming
+		OperationNameFunc func(ctx echo.Context) string
 	}
 )
 
@@ -72,8 +75,9 @@ var (
 		ComponentName: defaultComponentName,
 		IsBodyDump:    false,
 
-		LimitHTTPBody: true,
-		LimitSize:     60_000,
+		LimitHTTPBody:     true,
+		LimitSize:         60_000,
+		OperationNameFunc: defaultOperationName,
 	}
 )
 
@@ -130,6 +134,9 @@ func TraceWithConfig(config TraceConfig) echo.MiddlewareFunc {
 	if config.ComponentName == "" {
 		config.ComponentName = defaultComponentName
 	}
+	if config.OperationNameFunc == nil {
+		config.OperationNameFunc = defaultOperationName
+	}
 
 	return func(next echo.HandlerFunc) echo.HandlerFunc {
 		return func(c echo.Context) error {
@@ -138,7 +145,7 @@ func TraceWithConfig(config TraceConfig) echo.MiddlewareFunc {
 			}
 
 			req := c.Request()
-			opname := "HTTP " + req.Method + " URL: " + c.Path()
+			opname := config.OperationNameFunc(c)
 			realIP := c.RealIP()
 			requestID := getRequestID(c) // request-id generated by reverse-proxy
 
@@ -218,10 +225,10 @@ func TraceWithConfig(config TraceConfig) echo.MiddlewareFunc {
 
 func limitString(str string, size int) string {
 	if len(str) > size {
-        return str[:size/2] + "\n---- skipped ----\n" + str[len(str)-size/2:]
+		return str[:size/2] + "\n---- skipped ----\n" + str[len(str)-size/2:]
 	}
 
-    return str
+	return str
 }
 
 func logError(span opentracing.Span, err error) {
@@ -248,6 +255,11 @@ func generateToken() string {
 	return fmt.Sprintf("%x", b)
 }
 
+func defaultOperationName(ctx echo.Context) string {
+	req := ctx.Request()
+	return "HTTP " + req.Method + " URL: " + ctx.Path()
+}
+
 // TraceFunction wraps funtion with opentracing span adding tags for the function name and caller details
 func TraceFunction(ctx echo.Context, fn interface{}, params ...interface{}) (result []reflect.Value) {
 	// Get function name

jaegertracing/jaegertracing_test.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"net/http"
 	"net/http/httptest"
+	"strings"
 	"testing"
 
 	"github.com/labstack/echo/v4"
@@ -101,11 +102,14 @@ func (tr *mockTracer) currentSpan() *mockSpan {
 }
 
 func (tr *mockTracer) StartSpan(operationName string, opts ...opentracing.StartSpanOption) opentracing.Span {
-	tr.hasStartSpanWithOption = (len(opts) > 0)
+	tr.hasStartSpanWithOption = len(opts) > 0
 	if tr.span != nil {
+		tr.span.opName = operationName
 		return tr.span
 	}
-	return createSpan(tr)
+	span := createSpan(tr)
+	span.opName = operationName
+	return span
 }
 
 func (tr *mockTracer) Inject(sm opentracing.SpanContext, format interface{}, carrier interface{}) error {
@@ -325,3 +329,58 @@ func TestTraceWithoutLimitHTTPBody(t *testing.T) {
 	assert.Equal(t, "123456789012345678901234567890", tracer.currentSpan().getLog("http.req.body"))
 	assert.Equal(t, "Hi 123456789012345678901234567890", tracer.currentSpan().getLog("http.resp.body"))
 }
+
+func TestTraceWithDefaultOperationName(t *testing.T) {
+	tracer := createMockTracer()
+
+	e := echo.New()
+	e.Use(Trace(tracer))
+
+	e.GET("/trace", func(c echo.Context) error {
+		return c.String(http.StatusOK, "Hi")
+	})
+
+	req := httptest.NewRequest(http.MethodGet, "/trace", nil)
+	rec := httptest.NewRecorder()
+	e.ServeHTTP(rec, req)
+
+	assert.Equal(t, "HTTP GET URL: /trace", tracer.currentSpan().getOpName())
+}
+
+func TestTraceWithCustomOperationName(t *testing.T) {
+	tracer := createMockTracer()
+
+	e := echo.New()
+	e.Use(TraceWithConfig(TraceConfig{
+		Tracer:        tracer,
+		ComponentName: "EchoTracer",
+		OperationNameFunc: func(ctx echo.Context) string {
+			// This is an example of operation name customization
+			// In most cases default formatting is more than enough
+			req := ctx.Request()
+			opName := "HTTP " + req.Method
+
+			path := ctx.Path()
+			paramNames := ctx.ParamNames()
+
+			for _, name := range paramNames {
+				from := ":" + name
+				to := "{" + name + "}"
+				path = strings.ReplaceAll(path, from, to)
+			}
+			
+			return opName + " " + path
+		},
+	}))
+
+	e.GET("/trace/:traceID/spans/:spanID", func(c echo.Context) error {
+		return c.String(http.StatusOK, "Hi")
+	})
+
+	req := httptest.NewRequest(http.MethodGet, "/trace/123456/spans/123", nil)
+	rec := httptest.NewRecorder()
+	e.ServeHTTP(rec, req)
+
+	assert.Equal(t, true, tracer.currentSpan().isFinished())
+	assert.Equal(t, "HTTP GET /trace/{traceID}/spans/{spanID}", tracer.currentSpan().getOpName())
+}