Move code to pkg

pkg/middlewares/tracing/forwarder.go

@@ -0,0 +1,58 @@
+package tracing
+
+import (
+	"context"
+	"net/http"
+
+	"github.com/containous/traefik/pkg/middlewares"
+	"github.com/containous/traefik/pkg/tracing"
+	"github.com/opentracing/opentracing-go/ext"
+)
+
+const (
+	forwarderTypeName = "TracingForwarder"
+)
+
+type forwarderMiddleware struct {
+	router  string
+	service string
+	next    http.Handler
+}
+
+// NewForwarder creates a new forwarder middleware that traces the outgoing request.
+func NewForwarder(ctx context.Context, router, service string, next http.Handler) http.Handler {
+	middlewares.GetLogger(ctx, "tracing", forwarderTypeName).
+		Debugf("Added outgoing tracing middleware %s", service)
+
+	return &forwarderMiddleware{
+		router:  router,
+		service: service,
+		next:    next,
+	}
+}
+
+func (f *forwarderMiddleware) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
+	tr, err := tracing.FromContext(req.Context())
+	if err != nil {
+		f.next.ServeHTTP(rw, req)
+		return
+	}
+
+	opParts := []string{f.service, f.router}
+	span, req, finish := tr.StartSpanf(req, ext.SpanKindRPCClientEnum, "forward", opParts, "/")
+	defer finish()
+
+	span.SetTag("service.name", f.service)
+	span.SetTag("router.name", f.router)
+	ext.HTTPMethod.Set(span, req.Method)
+	ext.HTTPUrl.Set(span, req.URL.String())
+	span.SetTag("http.host", req.Host)
+
+	tracing.InjectRequestHeaders(req)
+
+	recorder := newStatusCodeRecoder(rw, 200)
+
+	f.next.ServeHTTP(recorder, req)
+
+	tracing.LogResponseCode(span, recorder.Status())
+}