Merge pull request #18 from ExpediaDotCom/fix-issue17

add HTTPHeadersCarrier support for tracer.Extract and tracer.Inject

examples/example.go

@@ -19,6 +19,7 @@ package main
 
 import (
 	"fmt"
+	"net/http"
 	"time"
 
 	haystack "github.com/ExpediaDotCom/haystack-client-go"
@@ -56,7 +57,16 @@ func main() {
 		}
 	}()
 
-	span1 := tracer.StartSpan("operation1", opentracing.Tag{Key: "my-tag", Value: "something"})
+	carrier := opentracing.HTTPHeadersCarrier(http.Header(map[string][]string{
+		"Trace-Id":  {"409dec0e-473e-11e9-81cc-186590cf29af"},
+		"Span-Id":   {"509df8d3-473e-11e9-81cc-186590cf29af"},
+		"Parent-Id": {"609df88c-473e-11e9-81cc-186590cf29af"},
+	}))
+	clientContext, err := tracer.Extract(opentracing.HTTPHeaders, carrier)
+	if err != nil {
+		panic(err)
+	}
+	span1 := tracer.StartSpan("operation1", opentracing.ChildOf(clientContext), opentracing.Tag{Key: "my-tag", Value: "something"})
 	span1.SetTag(string(ext.SpanKind), ext.SpanKindRPCServerEnum)
 	span1.SetTag(string(ext.Error), false)
 	span1.SetTag(string(ext.HTTPStatusCode), 200)
@@ -68,6 +78,12 @@ func main() {
 	ext.Error.Set(span2, true)
 	ext.HTTPStatusCode.Set(span1, 404)
 
+	// inject the span context in http header using tracer.Inject(...)
+	req, _ := http.NewRequest(http.MethodGet, "https://expediadotcom.github.io/haystack/", nil)
+	tracer.Inject(span2.Context(), opentracing.HTTPHeaders, opentracing.HTTPHeadersCarrier(req.Header))
+	//
+	//log.Println(req.Header)
+
 	span2.Finish()
 	span1.Finish()
 

propagator.go

@@ -21,6 +21,8 @@ import (
 	"fmt"
 	"net/url"
 	"strings"
+
+	"github.com/opentracing/opentracing-go"
 )
 
 /*Propagator defines the interface for injecting and extracing the SpanContext from the carrier*/
@@ -113,13 +115,17 @@ type TextMapPropagator struct {
 
 /*Inject injects the span context in the carrier*/
 func (p *TextMapPropagator) Inject(ctx *SpanContext, carrier interface{}) error {
-	carrierMap := carrier.(map[string]string)
-	carrierMap[p.opts.TraceIDKEY()] = ctx.TraceID
-	carrierMap[p.opts.SpanIDKEY()] = ctx.SpanID
-	carrierMap[p.opts.ParentSpanIDKEY()] = ctx.ParentID
+	textMapWriter, ok := carrier.(opentracing.TextMapWriter)
+	if !ok {
+		return opentracing.ErrInvalidCarrier
+	}
+
+	textMapWriter.Set(p.opts.TraceIDKEY(), ctx.TraceID)
+	textMapWriter.Set(p.opts.SpanIDKEY(), ctx.SpanID)
+	textMapWriter.Set(p.opts.ParentSpanIDKEY(), ctx.ParentID)
 
 	ctx.ForeachBaggageItem(func(key, value string) bool {
-		carrierMap[fmt.Sprintf("%s%s", p.opts.BaggageKeyPrefix(), key)] = p.codex.Encode(ctx.Baggage[key])
+		textMapWriter.Set(fmt.Sprintf("%s%s", p.opts.BaggageKeyPrefix(), key), p.codex.Encode(ctx.Baggage[key]))
 		return true
 	})
 
@@ -128,8 +134,11 @@ func (p *TextMapPropagator) Inject(ctx *SpanContext, carrier interface{}) error
 
 /*Extract the span context from the carrier*/
 func (p *TextMapPropagator) Extract(carrier interface{}) (*SpanContext, error) {
-	baggage := make(map[string](string))
-	carrierMap := carrier.(map[string]string)
+	textMapReader, ok := carrier.(opentracing.TextMapReader)
+
+	if !ok {
+		return nil, opentracing.ErrInvalidCarrier
+	}
 
 	baggageKeyLowerCasePrefix := strings.ToLower(p.opts.BaggageKeyPrefix())
 	traceIDKeyLowerCase := strings.ToLower(p.opts.TraceIDKEY())
@@ -140,19 +149,27 @@ func (p *TextMapPropagator) Extract(carrier interface{}) (*SpanContext, error) {
 	spanID := ""
 	parentSpanID := ""
 
-	for k, v := range carrierMap {
+	baggage := make(map[string]string)
+	err := textMapReader.ForeachKey(func(k, v string) error {
 		lcKey := strings.ToLower(k)
+
 		if strings.HasPrefix(lcKey, baggageKeyLowerCasePrefix) {
-			keySansPrefix := k[len(p.opts.BaggageKeyPrefix()):]
+			keySansPrefix := lcKey[len(p.opts.BaggageKeyPrefix()):]
 			baggage[keySansPrefix] = p.codex.Decode(v)
 		} else if lcKey == traceIDKeyLowerCase {
-			traceID = carrierMap[k]
+			traceID = v
 		} else if lcKey == spanIDKeyLowerCase {
-			spanID = carrierMap[k]
+			spanID = v
 		} else if lcKey == parentSpanIDKeyLowerCase {
-			parentSpanID = carrierMap[k]
+			parentSpanID = v
 		}
+		return nil
+	})
+
+	if err != nil {
+		return nil, err
 	}
+
 	return &SpanContext{
 		TraceID:            traceID,
 		SpanID:             spanID,

tracer_test.go

@@ -19,9 +19,11 @@ package haystack
 
 import (
 	"io"
+	"strings"
 	"testing"
 
 	opentracing "github.com/opentracing/opentracing-go"
+
 	"github.com/stretchr/testify/suite"
 )
 
@@ -90,14 +92,15 @@ func (suite *TracerTestSuite) TestTracerProperties() {
 func (suite *TracerTestSuite) TestTracerWithDualSpanMode_1() {
 	serverTag := opentracing.Tag{Key: "span.kind", Value: "server"}
 	clientTag := opentracing.Tag{Key: "span.kind", Value: "client"}
-	carrier := map[string]string{
+	headerMap := map[string]string{
 		"trace-id":        "T1",
 		"Span-ID":         "S1",
 		"Parent-ID":       "P1",
 		"Baggage-myKey":   "myVal",
 		"baggage-mykey-1": "myval",
 	}
-	upstreamSpanContext, _ := suite.dualSpanModeTracer.Extract(opentracing.HTTPHeaders, carrier)
+
+	upstreamSpanContext, _ := suite.dualSpanModeTracer.Extract(opentracing.HTTPHeaders, buildHTTPHeaderCarrier(headerMap))
 	serverSpan := suite.dualSpanModeTracer.StartSpan("op1", serverTag, opentracing.ChildOf(upstreamSpanContext))
 	clientSpan := suite.dualSpanModeTracer.StartSpan("op2", clientTag, opentracing.ChildOf(serverSpan.Context()))
 
@@ -112,8 +115,8 @@ func (suite *TracerTestSuite) TestTracerWithDualSpanMode_1() {
 	receivedServerSpan := dispatcher.spans[1]
 	receivedServerSpanCtx := receivedServerSpan.Context().(*SpanContext)
 	suite.Equal(receivedServerSpanCtx.TraceID, "T1", "Trace Ids should match")
-	suite.Equal(receivedServerSpanCtx.Baggage["myKey"], "myVal", "baggage key should match")
-	suite.Equal(receivedServerSpanCtx.Baggage["mykey-1"], "myval", "baggage lowercase key should match")
+	suite.Equal(receivedServerSpanCtx.Baggage[strings.ToLower("myKey")], "myVal", "baggage key should match")
+	suite.Equal(receivedServerSpanCtx.Baggage[strings.ToLower("mykey-1")], "myval", "baggage lowercase key should match")
 	suite.NotEqual(receivedServerSpanCtx.SpanID, "S1", "SpanId should be newly created")
 	suite.NotEqual(receivedServerSpanCtx.SpanID, "P1", "SpanId should be newly created")
 	suite.NotEqual(receivedServerSpanCtx.SpanID, "T1", "SpanId should be newly created")
@@ -131,12 +134,13 @@ func (suite *TracerTestSuite) TestTracerWithDualSpanMode_1() {
 func (suite *TracerTestSuite) TestTracerWithSingleSpanMode_1() {
 	serverTag := opentracing.Tag{Key: "span.kind", Value: "server"}
 	clientTag := opentracing.Tag{Key: "span.kind", Value: "client"}
-	carrier := map[string]string{
+	headerMap := map[string]string{
 		"Trace-ID":  "T1",
 		"Span-ID":   "S1",
 		"Parent-ID": "P1",
 	}
-	upstreamSpanContext, _ := suite.tracer.Extract(opentracing.HTTPHeaders, carrier)
+
+	upstreamSpanContext, _ := suite.tracer.Extract(opentracing.HTTPHeaders, buildHTTPHeaderCarrier(headerMap))
 	serverSpan := suite.tracer.StartSpan("op1", serverTag, opentracing.ChildOf(upstreamSpanContext))
 	clientSpan := suite.tracer.StartSpan("op2", clientTag, opentracing.ChildOf(serverSpan.Context()))
 
@@ -166,12 +170,13 @@ func (suite *TracerTestSuite) TestTracerWithSingleSpanMode_1() {
 func (suite *TracerTestSuite) TestTracerWithSingleSpanMode_2() {
 	serverTag := opentracing.Tag{Key: "error", Value: true}
 	clientTag := opentracing.Tag{Key: "error", Value: false}
-	carrier := map[string]string{
+	headerMap := map[string]string{
 		"Trace-ID":  "T1",
 		"Span-ID":   "S1",
 		"Parent-ID": "P1",
 	}
-	upstreamSpanContext, _ := suite.tracer.Extract(opentracing.HTTPHeaders, carrier)
+
+	upstreamSpanContext, _ := suite.tracer.Extract(opentracing.HTTPHeaders, buildHTTPHeaderCarrier(headerMap))
 	serverSpan := suite.tracer.StartSpan("op1", serverTag, opentracing.ChildOf(upstreamSpanContext))
 	clientSpan := suite.tracer.StartSpan("op2", clientTag, opentracing.ChildOf(serverSpan.Context()))
 
@@ -202,7 +207,8 @@ func (suite *TracerTestSuite) TestTracerWithSingleSpanMode_2() {
 }
 
 func (suite *TracerTestSuite) TestTracerInject() {
-	carrier := make(map[string]string)
+	carrier := opentracing.HTTPHeadersCarrier(make(map[string][]string))
+
 	span1 := suite.tracer.StartSpan("op1")
 	err := suite.tracer.Inject(span1.Context(), opentracing.HTTPHeaders, carrier)
 	if err != nil {
@@ -215,12 +221,20 @@ func (suite *TracerTestSuite) TestTracerInject() {
 		panic(err)
 	}
 
-	suite.Equal(carrier["Trace-ID"], ctx.(*SpanContext).TraceID)
-	suite.Equal(carrier["Span-ID"], ctx.(*SpanContext).SpanID)
-	suite.Equal(carrier["Parent-ID"], ctx.(*SpanContext).ParentID)
+	suite.NotEqual("", ctx.(*SpanContext).TraceID)
+	suite.NotEqual("", ctx.(*SpanContext).SpanID)
+	suite.Equal("", ctx.(*SpanContext).ParentID)
 	suite.Equal(true, ctx.(*SpanContext).IsExtractedContext)
 }
 
+func buildHTTPHeaderCarrier(headerMap map[string]string) *opentracing.HTTPHeadersCarrier {
+	httpHeaderCarrier := opentracing.HTTPHeadersCarrier(make(map[string][]string))
+	for k, v := range headerMap {
+		httpHeaderCarrier.Set(k, v)
+	}
+	return &httpHeaderCarrier
+}
+
 func TestUnitTracerSuite(t *testing.T) {
 	suite.Run(t, new(TracerTestSuite))
 }