contrib/gin-gonic/gin: propagate gin errors to tracing spans

Author: theo303

contrib/gin-gonic/gin/gintrace.go

@@ -53,7 +53,12 @@ func Middleware(service string, opts ...Option) gin.HandlerFunc {
 		opts = append(opts, httptrace.HeaderTagsFromRequest(c.Request, cfg.headerTags))
 		span, ctx, finishSpans := httptrace.StartRequestSpan(c.Request, opts...)
 		defer func() {
-			finishSpans(c.Writer.Status(), nil)
+			status := c.Writer.Status()
+			err := c.Errors.Last()
+			if err != nil && cfg.isStatusError(status) {
+				finishSpans(status, cfg.isStatusError, tracer.WithError(err))
+			}
+			finishSpans(status, cfg.isStatusError)
 		}()
 
 		// pass the span through the request context

contrib/gin-gonic/gin/gintrace_test.go

@@ -210,7 +210,7 @@ func TestError(t *testing.T) {
 		assert.Equal("500", span.Tag(ext.HTTPCode))
 		assert.Equal(fmt.Sprintf("Error #01: %s\n", responseErr), span.Tag("gin.errors"))
 		// server errors set the ext.ErrorMsg tag
-		assert.Equal("500: Internal Server Error", span.Tag(ext.ErrorMsg))
+		assert.Equal("oh no", span.Tag(ext.ErrorMsg))
 		assert.Equal(ext.SpanKindServer, span.Tag(ext.SpanKind))
 		assert.Equal("gin-gonic/gin", span.Tag(ext.Component))
 		assert.Equal(componentName, span.Integration())

contrib/gin-gonic/gin/option.go

@@ -19,6 +19,7 @@ type config struct {
 	resourceNamer func(c *gin.Context) string
 	serviceName   string
 	ignoreRequest func(c *gin.Context) bool
+	isStatusError func(statusCode int) bool
 	headerTags    instrumentation.HeaderTags
 }
 
@@ -32,6 +33,7 @@ func newConfig(serviceName string) *config {
 		resourceNamer: defaultResourceNamer,
 		serviceName:   serviceName,
 		ignoreRequest: func(_ *gin.Context) bool { return false },
+		isStatusError: isServerError,
 		headerTags:    instr.HTTPHeadersAsTags(),
 	}
 }
@@ -79,6 +81,18 @@ func WithResourceNamer(namer func(c *gin.Context) string) OptionFn {
 	}
 }
 
+// WithStatusCheck specifies a function fn which reports whether the passed
+// statusCode should be considered an error.
+func WithStatusCheck(fn func(statusCode int) bool) OptionFn {
+	return func(cfg *config) {
+		cfg.isStatusError = fn
+	}
+}
+
+func isServerError(statusCode int) bool {
+	return statusCode >= 500 && statusCode < 600
+}
+
 // WithHeaderTags enables the integration to attach HTTP request headers as span tags.
 // Warning:
 // Using this feature can risk exposing sensitive data such as authorization tokens to Datadog.