contrib/labstack/echo.v4: add WithErrorTranslator Option (#2169)

Co-authored-by: Zarir Hamza <zarir.hamza@datadoghq.com>
Co-authored-by: Rodrigo Argüello <rodrigo.arguello@datadoghq.com>
Co-authored-by: Andrew Glaude <andrew.glaude@datadoghq.com>

contrib/labstack/echo.v4/echotrace.go

@@ -7,7 +7,6 @@
 package echo
 
 import (
-	"errors"
 	"fmt"
 	"math"
 	"net/http"
@@ -88,8 +87,7 @@ func Middleware(opts ...Option) echo.MiddlewareFunc {
 
 				// It is impossible to determine what the final status code of a request is in echo.
 				// This is the best we can do.
-				var echoErr *echo.HTTPError
-				if errors.As(err, &echoErr) {
+				if echoErr, ok := cfg.translateError(err); ok {
 					if cfg.isStatusError(echoErr.Code) {
 						finishOpts = append(finishOpts, tracer.WithError(err))
 					}

contrib/labstack/echo.v4/echotrace_test.go

@@ -424,6 +424,57 @@ func TestIgnoreRequestFunc(t *testing.T) {
 	assert.Len(spans, 0)
 }
 
+type testCustomError struct {
+	TestCode int
+}
+
+// Error satisfies the apierror interface
+func (e *testCustomError) Error() string {
+	return "test"
+}
+
+func TestWithErrorTranslator(t *testing.T) {
+	assert := assert.New(t)
+	mt := mocktracer.Start()
+	defer mt.Stop()
+	var called, traced bool
+
+	// setup
+	translateError := func(e error) (*echo.HTTPError, bool) {
+		return &echo.HTTPError{
+			Message: e.(*testCustomError).Error(),
+			Code:    e.(*testCustomError).TestCode,
+		}, true
+	}
+	router := echo.New()
+	router.Use(Middleware(WithErrorTranslator(translateError)))
+
+	// a handler with an error and make the requests
+	router.GET("/err", func(c echo.Context) error {
+		_, traced = tracer.SpanFromContext(c.Request().Context())
+		called = true
+		return &testCustomError{
+			TestCode: 401,
+		}
+	})
+	r := httptest.NewRequest("GET", "/err", nil)
+	w := httptest.NewRecorder()
+	router.ServeHTTP(w, r)
+
+	// verify the error is correct and the stacktrace is disabled
+	assert.True(called)
+	assert.True(traced)
+
+	spans := mt.FinishedSpans()
+	require.Len(t, spans, 1)
+	span := spans[0]
+	assert.Equal("http.request", span.OperationName())
+	assert.Equal(ext.SpanTypeWeb, span.Tag(ext.SpanType))
+	assert.Contains(span.Tag(ext.ResourceName), "/err")
+	assert.Equal("401", span.Tag(ext.HTTPCode))
+	assert.Equal("GET", span.Tag(ext.HTTPMethod))
+}
+
 func TestNamingSchema(t *testing.T) {
 	genSpans := namingschematest.GenSpansFn(func(t *testing.T, serviceOverride string) []mocktracer.Span {
 		var opts []Option

contrib/labstack/echo.v4/option.go

@@ -6,6 +6,7 @@
 package echo
 
 import (
+	"errors"
 	"math"
 
 	"gopkg.in/DataDog/dd-trace-go.v1/internal"
@@ -24,6 +25,7 @@ type config struct {
 	noDebugStack      bool
 	ignoreRequestFunc IgnoreRequestFunc
 	isStatusError     func(statusCode int) bool
+	translateError    func(err error) (*echo.HTTPError, bool)
 	headerTags        *internal.LockMap
 }
 
@@ -38,6 +40,13 @@ func defaults(cfg *config) {
 	cfg.analyticsRate = math.NaN()
 	cfg.isStatusError = isServerError
 	cfg.headerTags = globalconfig.HeaderTagMap()
+	cfg.translateError = func(err error) (*echo.HTTPError, bool) {
+		var echoErr *echo.HTTPError
+		if errors.As(err, &echoErr) {
+			return echoErr, true
+		}
+		return nil, false
+	}
 }
 
 // WithServiceName sets the given service name for the system.
@@ -87,6 +96,14 @@ func WithIgnoreRequest(ignoreRequestFunc IgnoreRequestFunc) Option {
 	}
 }
 
+// WithErrorTranslator sets a function to translate Go errors into echo Errors.
+// This is used for extracting the HTTP response status code.
+func WithErrorTranslator(fn func(err error) (*echo.HTTPError, bool)) Option {
+	return func(cfg *config) {
+		cfg.translateError = fn
+	}
+}
+
 // WithStatusCheck specifies a function fn which reports whether the passed
 // statusCode should be considered an error.
 func WithStatusCheck(fn func(statusCode int) bool) Option {