traefik/tracing/tracing.go

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2018-11-14 09:18:03 +00:00
package tracing
import (
"context"
"fmt"
"io"
"net/http"
"github.com/containous/traefik/log"
"github.com/opentracing/opentracing-go"
"github.com/opentracing/opentracing-go/ext"
)
type contextKey int
const (
// SpanKindNoneEnum Span kind enum none.
SpanKindNoneEnum ext.SpanKindEnum = "none"
tracingKey contextKey = iota
)
// WithTracing Adds Tracing into the context.
func WithTracing(ctx context.Context, tracing *Tracing) context.Context {
return context.WithValue(ctx, tracingKey, tracing)
}
// FromContext Gets Tracing from context.
func FromContext(ctx context.Context) (*Tracing, error) {
if ctx == nil {
panic("nil context")
}
tracer, ok := ctx.Value(tracingKey).(*Tracing)
if !ok {
return nil, fmt.Errorf("unable to find tracing in the context")
}
return tracer, nil
}
// TrackingBackend is an abstraction for tracking backend (Jaeger, Zipkin, ...).
type TrackingBackend interface {
Setup(componentName string) (opentracing.Tracer, io.Closer, error)
}
// Tracing middleware.
type Tracing struct {
ServiceName string `description:"Set the name for this service" export:"true"`
SpanNameLimit int `description:"Set the maximum character limit for Span names (default 0 = no limit)" export:"true"`
tracer opentracing.Tracer
closer io.Closer
}
// NewTracing Creates a Tracing.
func NewTracing(serviceName string, spanNameLimit int, trackingBackend TrackingBackend) (*Tracing, error) {
tracing := &Tracing{
ServiceName: serviceName,
SpanNameLimit: spanNameLimit,
}
var err error
tracing.tracer, tracing.closer, err = trackingBackend.Setup(serviceName)
if err != nil {
return nil, err
}
return tracing, nil
}
// StartSpan delegates to opentracing.Tracer.
func (t *Tracing) StartSpan(operationName string, opts ...opentracing.StartSpanOption) opentracing.Span {
return t.tracer.StartSpan(operationName, opts...)
}
// StartSpanf delegates to StartSpan.
func (t *Tracing) StartSpanf(r *http.Request, spanKind ext.SpanKindEnum, opPrefix string, opParts []string, separator string, opts ...opentracing.StartSpanOption) (opentracing.Span, *http.Request, func()) {
operationName := generateOperationName(opPrefix, opParts, separator, t.SpanNameLimit)
return StartSpan(r, operationName, spanKind, opts...)
}
// Inject delegates to opentracing.Tracer.
func (t *Tracing) Inject(sm opentracing.SpanContext, format interface{}, carrier interface{}) error {
return t.tracer.Inject(sm, format, carrier)
}
// Extract delegates to opentracing.Tracer.
func (t *Tracing) Extract(format interface{}, carrier interface{}) (opentracing.SpanContext, error) {
return t.tracer.Extract(format, carrier)
}
// 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 {
err := t.closer.Close()
if err != nil {
log.WithoutContext().Warn(err)
}
}
}
// 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 {
err := opentracing.GlobalTracer().Inject(
span.Context(),
opentracing.HTTPHeaders,
HTTPHeadersCarrier(r.Header))
if err != nil {
log.FromContext(r.Context()).Error(err)
}
}
}
// 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, spanKind ext.SpanKindEnum, opts ...opentracing.StartSpanOption) (opentracing.Span, *http.Request, func()) {
span, ctx := opentracing.StartSpanFromContext(r.Context(), operationName, opts...)
switch spanKind {
case ext.SpanKindRPCClientEnum:
ext.SpanKindRPCClient.Set(span)
case ext.SpanKindRPCServerEnum:
ext.SpanKindRPCServer.Set(span)
case ext.SpanKindProducerEnum:
ext.SpanKindProducer.Set(span)
case ext.SpanKindConsumerEnum:
ext.SpanKindConsumer.Set(span)
default:
// noop
}
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)
}
}
// SetErrorWithEvent flags the span associated with this request as in error and log an event.
func SetErrorWithEvent(r *http.Request, format string, args ...interface{}) {
SetError(r)
LogEventf(r, format, args...)
}