Add HTTP method and path to trace span operation name (fabiolb#715)

* Add HTTP method and path to span operation name

Also, set HTTP method and URL span tags.

* Add tracing span name option as template

config/config.go

@@ -178,6 +178,7 @@ type Tracing struct {
 	Topic          string
 	SamplerRate    float64
 	SpanHost       string
+	SpanName       string
 	TraceID128Bit  bool
 }
 

config/default.go

@@ -101,6 +101,7 @@ var defaultConfig = &Config{
 		Topic:          "Fabiolb-Kafka-Topic",
 		SamplerRate:    -1,
 		SpanHost:       "localhost:9998",
+		SpanName:       "",
 		TraceID128Bit:  true,
 	},
 

config/load.go

@@ -204,6 +204,7 @@ func load(cmdline, environ, envprefix []string, props *properties.Properties) (c
 	f.StringVar(&cfg.Tracing.CollectorType, "tracing.CollectorType", defaultConfig.Tracing.CollectorType, "OpenTrace Collector Type, one of [http, kafka]")
 	f.StringVar(&cfg.Tracing.ConnectString, "tracing.ConnectString", defaultConfig.Tracing.ConnectString, "OpenTrace Collector host:port")
 	f.StringVar(&cfg.Tracing.ServiceName, "tracing.ServiceName", defaultConfig.Tracing.ServiceName, "Service name to embed in OpenTrace span")
+	f.StringVar(&cfg.Tracing.SpanName, "tracing.SpanName", defaultConfig.Tracing.SpanName, "Span name template used to embed in OpenTrace span")
 	f.StringVar(&cfg.Tracing.Topic, "tracing.Topic", defaultConfig.Tracing.Topic, "OpenTrace Collector Kafka Topic")
 	f.Float64Var(&cfg.Tracing.SamplerRate, "tracing.SamplerRate", defaultConfig.Tracing.SamplerRate, "OpenTrace sample rate percentage in decimal form")
 	f.StringVar(&cfg.Tracing.SpanHost, "tracing.SpanHost", defaultConfig.Tracing.SpanHost, "Host:Port info to add to spans")

fabio.properties

@@ -1290,6 +1290,28 @@
 # tracing.ServiceName = Fabiolb
 
 
+# tracing.SpanName configures the template used in reporting span information
+#
+# The value is expanded by the text/template package and provides
+# the following variables:
+#
+#  - Proto:       the protocol version
+#  - Method:      the HTTP method
+#  - Host:        the host part of the URL
+#  - Scheme:      the scheme of the requested URL
+#  - Path:        the path of the requested URL
+#  - RawQuery:    the encoded query values of the requested URL
+#
+# SpanName defaults to the value of tracing.ServiceName but can be
+# overridden with this property.
+#
+# Example: tracing.SpanName = {{.Proto}} {{.Method}} {{.Path}}
+#
+# The default is
+#
+# tracing.SpanName =
+
+
 # tracing.Topic sets the Topic String used if tracing.CollectorType is kafka and
 # tracing.ConnectSting is set to a kafka broker
 #
@@ -1313,4 +1335,3 @@
 #
 # The default is
 # tracing.SpanHost = localhost:9998
-

proxy/http_proxy.go

@@ -55,7 +55,7 @@ type HTTPProxy struct {
 	// Logger is the access logger for the requests.
 	Logger logger.Logger
 
-	// TracerCfg is the Open Tracing  configuration as provided during startup
+	// TracerCfg is the Open Tracing configuration as provided during startup
 	TracerCfg config.Tracing
 
 	// UUID returns a unique id in uuid format.
@@ -80,7 +80,7 @@ func (p *HTTPProxy) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 
 	//Create Span
-	span := trace.CreateSpan(r, p.TracerCfg.ServiceName)
+	span := trace.CreateSpan(r, &p.TracerCfg)
 	defer span.Finish()
 
 	t := p.Lookup(r)

trace/trace.go

@@ -1,11 +1,13 @@
 package trace
 
 import (
+	"bytes"
 	"fmt"
 	"log"
 	"net/http"
 	"os"
 	"strings"
+	"text/template"
 
 	"github.com/fabiolb/fabio/config"
 	opentracing "github.com/opentracing/opentracing-go"
@@ -63,18 +65,25 @@ func CreateTracer(recorder zipkin.SpanRecorder, samplerRate float64, traceID128B
 	return tracer
 }
 
-func CreateSpan(r *http.Request, serviceName string) opentracing.Span {
+func CreateSpan(r *http.Request, cfg *config.Tracing) opentracing.Span {
 	globalTracer := opentracing.GlobalTracer()
 
+	name := cfg.ServiceName
+	if cfg.SpanName != "" {
+		name = spanName(cfg.SpanName, r)
+	}
+
 	// If headers contain trace data, create child span from parent; else, create root span
 	var span opentracing.Span
 	if globalTracer != nil {
 		spanCtx, err := globalTracer.Extract(opentracing.HTTPHeaders, opentracing.HTTPHeadersCarrier(r.Header))
 		if err != nil {
-			span = globalTracer.StartSpan(serviceName)
+			span = globalTracer.StartSpan(name)
 		} else {
-			span = globalTracer.StartSpan(serviceName, ext.RPCServerOption(spanCtx))
+			span = globalTracer.StartSpan(name, ext.RPCServerOption(spanCtx))
 		}
+		ext.HTTPMethod.Set(span, r.Method)
+		ext.HTTPUrl.Set(span, r.URL.String())
 	}
 
 	return span // caller must defer span.finish()
@@ -98,3 +107,24 @@ func InitializeTracer(traceConfig *config.Tracing) {
 	// Set the Zipkin Tracer created above to the GlobalTracer
 	opentracing.SetGlobalTracer(tracer)
 }
+
+// spanName returns the rendered span name from the configured template.
+// If an error is encountered, it returns the unrendered template.
+func spanName(tmplStr string, r *http.Request) string {
+	tmpl, err := template.New("name").Parse(tmplStr)
+	if err != nil {
+		return tmplStr
+	}
+
+	var name bytes.Buffer
+
+	data := struct {
+		Proto, Method, Host, Scheme, Path, RawQuery string
+	}{r.Proto, r.Method, r.Host, r.URL.Scheme, r.URL.Path, r.URL.RawQuery}
+
+	if err = tmpl.Execute(&name, data); err != nil {
+		return tmplStr
+	}
+
+	return name.String()
+}

trace/trace_test.go

@@ -24,7 +24,7 @@ func TestCreateSpanNoGlobalTracer(t *testing.T) {
 	opentracing.SetGlobalTracer(nil)
 	req, _ := http.NewRequest("GET", "http://example.com", nil)
 
-	if CreateSpan(req, testServiceName) != nil {
+	if CreateSpan(req, &config.Tracing{ServiceName: "fabiolb-test", SpanName: "{{.Method}} {{.Path}}"}) != nil {
 		t.Error("CreateSpan returned a non-nil result using a nil global tracer.")
 		t.Fail()
 	}
@@ -35,7 +35,7 @@ func TestCreateSpanWithNoParent(t *testing.T) {
 	opentracing.SetGlobalTracer(tracer)
 
 	req, _ := http.NewRequest("GET", "http://example.com", nil)
-	if CreateSpan(req, testServiceName) == nil {
+	if CreateSpan(req, &config.Tracing{ServiceName: "fabiolb-test", SpanName: "{{.Method}} {{.Path}}"}) == nil {
 		t.Error("Received nil span while a global tracer was set.")
 		t.FailNow()
 	}
@@ -53,7 +53,7 @@ func TestCreateSpanWithParent(t *testing.T) {
 		opentracing.HTTPHeadersCarrier(requestIn.Header),
 	)
 
-	if CreateSpan(requestIn, testServiceName+"-child") == nil {
+	if CreateSpan(requestIn, &config.Tracing{ServiceName: "fabiolb-test", SpanName: "{{.Method}} {{.Path}}"}) == nil {
 		t.Error("Received a nil span while a global tracer was set.")
 		t.FailNow()
 	}
@@ -128,3 +128,22 @@ func TestInjectHeadersWithParentSpan(t *testing.T) {
 		t.Fail()
 	}
 }
+
+func TestSpanName(t *testing.T) {
+	req, _ := http.NewRequest("GET", "http://example.com/demo", nil)
+
+	if spanName("{{.Method}} {{.Host}} {{.Path}}", req) != "GET example.com /demo" {
+		t.Error("spanName did not properly render the supported template")
+		t.Fail()
+	}
+
+	if spanName("{{.Invalid", req) != "{{.Invalid" {
+		t.Error("spanName did not return the unrendered string of the invalid template")
+		t.Fail()
+	}
+
+	if spanName("{{.Unsupported}}", req) != "{{.Unsupported}}" {
+		t.Error("spanName did not return the unrendered string of the unsupported template")
+		t.Fail()
+	}
+}