Opentracing support

middlewares/tracing/tracing.go

@@ -0,0 +1,150 @@
+package tracing
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/containous/traefik/log"
+	"github.com/containous/traefik/middlewares/tracing/jaeger"
+	"github.com/containous/traefik/middlewares/tracing/zipkin"
+	"github.com/opentracing/opentracing-go"
+	"github.com/opentracing/opentracing-go/ext"
+)
+
+// Tracing middleware
+type Tracing struct {
+	Backend     string         `description:"Selects the tracking backend ('jaeger','zipkin')." export:"true"`
+	ServiceName string         `description:"Set the name for this service" export:"true"`
+	Jaeger      *jaeger.Config `description:"Settings for jaeger"`
+	Zipkin      *zipkin.Config `description:"Settings for zipkin"`
+
+	opentracing.Tracer
+	closer io.Closer
+}
+
+// Backend describes things we can use to setup tracing
+type Backend interface {
+	Setup(serviceName string) (opentracing.Tracer, io.Closer, error)
+}
+
+type statusCodeTracker struct {
+	http.ResponseWriter
+	status int
+}
+
+func (s *statusCodeTracker) WriteHeader(status int) {
+	s.status = status
+	s.ResponseWriter.WriteHeader(status)
+}
+
+// Setup Tracing middleware
+func (t *Tracing) Setup() {
+	var err error
+
+	switch t.Backend {
+	case jaeger.Name:
+		t.Tracer, t.closer, err = t.Jaeger.Setup(t.ServiceName)
+	case zipkin.Name:
+		t.Tracer, t.closer, err = t.Zipkin.Setup(t.ServiceName)
+	default:
+		log.Warnf("Unknown tracer %q", t.Backend)
+		return
+	}
+
+	if err != nil {
+		log.Warnf("Could not initialize %s tracing: %v", t.Backend, err)
+		return
+	}
+
+	return
+}
+
+// IsEnabled determines if tracing was successfully activated
+func (t *Tracing) IsEnabled() bool {
+	if t == nil || t.Tracer == nil {
+		return false
+	}
+	return true
+}
+
+// Close tracer
+func (t *Tracing) Close() {
+	if t.closer != nil {
+		t.closer.Close()
+	}
+}
+
+// LogRequest used to create span tags from the request
+func LogRequest(span opentracing.Span, r *http.Request) {
+	if span != nil && r != nil {
+		ext.HTTPMethod.Set(span, r.Method)
+		ext.HTTPUrl.Set(span, r.URL.String())
+		span.SetTag("http.host", r.Host)
+	}
+}
+
+// LogResponseCode used to log response code in span
+func LogResponseCode(span opentracing.Span, code int) {
+	if span != nil {
+		ext.HTTPStatusCode.Set(span, uint16(code))
+		if code >= 400 {
+			ext.Error.Set(span, true)
+		}
+	}
+}
+
+// GetSpan used to retrieve span from request context
+func GetSpan(r *http.Request) opentracing.Span {
+	return opentracing.SpanFromContext(r.Context())
+}
+
+// InjectRequestHeaders used to inject OpenTracing headers into the request
+func InjectRequestHeaders(r *http.Request) {
+	if span := GetSpan(r); span != nil {
+		opentracing.GlobalTracer().Inject(
+			span.Context(),
+			opentracing.HTTPHeaders,
+			opentracing.HTTPHeadersCarrier(r.Header))
+	}
+}
+
+// LogEventf logs an event to the span in the request context.
+func LogEventf(r *http.Request, format string, args ...interface{}) {
+	if span := GetSpan(r); span != nil {
+		span.LogKV("event", fmt.Sprintf(format, args...))
+	}
+}
+
+// StartSpan starts a new span from the one in the request context
+func StartSpan(r *http.Request, operationName string, spanKinClient bool, opts ...opentracing.StartSpanOption) (opentracing.Span, *http.Request, func()) {
+	span, ctx := opentracing.StartSpanFromContext(r.Context(), operationName, opts...)
+	if spanKinClient {
+		ext.SpanKindRPCClient.Set(span)
+	}
+	r = r.WithContext(ctx)
+	return span, r, func() {
+		span.Finish()
+	}
+}
+
+// SetError flags the span associated with this request as in error
+func SetError(r *http.Request) {
+	if span := GetSpan(r); span != nil {
+		ext.Error.Set(span, true)
+	}
+}
+
+// SetErrorAndDebugLog flags the span associated with this request as in error and create a debug log
+func SetErrorAndDebugLog(r *http.Request, format string, args ...interface{}) {
+	SetError(r)
+	log.Debugf(format, args...)
+	LogEventf(r, format, args...)
+}
+
+// SetErrorAndWarnLog flags the span associated with this request as in error and create a debug log
+func SetErrorAndWarnLog(r *http.Request, format string, args ...interface{}) {
+	SetError(r)
+	log.Warnf(format, args...)
+	LogEventf(r, format, args...)
+}