[plugin][trace] - Have a consistent spanName (#4171)

Automatically submitted.

plugin/trace/README.md

@@ -28,9 +28,16 @@ Additional features can be enabled with this syntax:
 
 ~~~
 trace [ENDPOINT-TYPE] [ENDPOINT] {
-	every AMOUNT
-	service NAME
-	client_server
+    every AMOUNT
+    service NAME
+    client_server
+}
+~~~
+~~~
+trace datadog {
+    every AMOUNT
+    service NAME
+    datadog_analytics_rate RATE
 }
 ~~~
 
@@ -39,6 +46,8 @@ trace [ENDPOINT-TYPE] [ENDPOINT] {
 * `service` **NAME** allows you to specify the service name reported to the tracing server.
   Default is `coredns`.
 * `client_server` will enable the `ClientServerSameSpan` OpenTracing feature.
+* `datadog_analytics_rate` **RATE** will enable [trace analytics](https://docs.datadoghq.com/tracing/app_analytics) on the traces sent
+  from *0* to *1*, *1* being every trace sent will be analyzed. This is a datadog only feature.
 
 ## Zipkin
 You can run Zipkin on a Docker host like this:

plugin/trace/setup.go

@@ -83,6 +83,21 @@ func traceParse(c *caddy.Controller) (*trace, error) {
 				if err != nil {
 					return nil, err
 				}
+			case "datadog_analytics_rate":
+				args := c.RemainingArgs()
+				if len(args) > 1 {
+					return nil, c.ArgErr()
+				}
+				tr.datadogAnalyticsRate = 0
+				if len(args) == 1 {
+					tr.datadogAnalyticsRate,err = strconv.ParseFloat(args[0], 64)
+				}
+				if err != nil {
+					return nil, err
+				}
+				if tr.datadogAnalyticsRate > 1 || tr.datadogAnalyticsRate < 0 {
+					return nil,fmt.Errorf("datadog analytics rate must be between 0 and 1, '%f' is not supported", tr.datadogAnalyticsRate )
+				}
 			}
 		}
 	}

plugin/trace/setup_test.go

@@ -22,6 +22,7 @@ func TestTraceParse(t *testing.T) {
 		{`trace zipkin localhost:1234`, false, "http://localhost:1234/api/v1/spans", 1, `coredns`, false},
 		{`trace datadog localhost`, false, "localhost", 1, `coredns`, false},
 		{`trace datadog http://localhost:8127`, false, "http://localhost:8127", 1, `coredns`, false},
+		{"trace datadog localhost {\n datadog_analytics_rate 0.1\n}", false, "localhost", 1, `coredns`, false},
 		{"trace {\n every 100\n}", false, "http://localhost:9411/api/v1/spans", 100, `coredns`, false},
 		{"trace {\n every 100\n service foobar\nclient_server\n}", false, "http://localhost:9411/api/v1/spans", 100, `foobar`, true},
 		{"trace {\n every 2\n client_server true\n}", false, "http://localhost:9411/api/v1/spans", 2, `coredns`, true},
@@ -29,6 +30,7 @@ func TestTraceParse(t *testing.T) {
 		// fails
 		{`trace footype localhost:4321`, true, "", 1, "", false},
 		{"trace {\n every 2\n client_server junk\n}", true, "", 1, "", false},
+		{"trace datadog localhost {\n datadog_analytics_rate 2\n}", true, "", 1, "", false},
 	}
 	for i, test := range tests {
 		c := caddy.NewTestController("dns", test.input)

plugin/trace/trace.go

@@ -8,7 +8,6 @@ import (
 	"sync/atomic"
 
 	"github.com/coredns/coredns/plugin"
-	"github.com/coredns/coredns/plugin/metrics"
 	"github.com/coredns/coredns/plugin/pkg/dnstest"
 	"github.com/coredns/coredns/plugin/pkg/log"
 	"github.com/coredns/coredns/plugin/pkg/rcode"
@@ -20,30 +19,33 @@ import (
 	zipkinot "github.com/openzipkin-contrib/zipkin-go-opentracing"
 	"github.com/openzipkin/zipkin-go"
 	zipkinhttp "github.com/openzipkin/zipkin-go/reporter/http"
+	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/ext"
 	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/opentracer"
 	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
 )
 
 const (
-	tagName   = "coredns.io/name"
-	tagType   = "coredns.io/type"
-	tagRcode  = "coredns.io/rcode"
-	tagProto  = "coredns.io/proto"
-	tagRemote = "coredns.io/remote"
+	tagName                 = "coredns.io/name"
+	tagType                 = "coredns.io/type"
+	tagRcode                = "coredns.io/rcode"
+	tagProto                = "coredns.io/proto"
+	tagRemote               = "coredns.io/remote"
+	defaultTopLevelSpanName = "servedns"
 )
 
 type trace struct {
 	count uint64 // as per Go spec, needs to be first element in a struct
 
-	Next            plugin.Handler
-	Endpoint        string
-	EndpointType    string
-	tracer          ot.Tracer
-	serviceEndpoint string
-	serviceName     string
-	clientServer    bool
-	every           uint64
-	Once            sync.Once
+	Next                 plugin.Handler
+	Endpoint             string
+	EndpointType         string
+	tracer               ot.Tracer
+	serviceEndpoint      string
+	serviceName          string
+	clientServer         bool
+	every                uint64
+	datadogAnalyticsRate float64
+	Once                 sync.Once
 }
 
 func (t *trace) Tracer() ot.Tracer {
@@ -58,7 +60,13 @@ func (t *trace) OnStartup() error {
 		case "zipkin":
 			err = t.setupZipkin()
 		case "datadog":
-			tracer := opentracer.New(tracer.WithAgentAddr(t.Endpoint), tracer.WithServiceName(t.serviceName), tracer.WithDebugMode(log.D.Value()))
+			tracer := opentracer.New(
+				tracer.WithAgentAddr(t.Endpoint),
+				tracer.WithDebugMode(log.D.Value()),
+				tracer.WithGlobalTag(ext.SpanTypeDNS, true),
+				tracer.WithServiceName(t.serviceName),
+				tracer.WithAnalyticsRate(t.datadogAnalyticsRate),
+			)
 			t.tracer = tracer
 		default:
 			err = fmt.Errorf("unknown endpoint type: %s", t.EndpointType)
@@ -73,7 +81,10 @@ func (t *trace) setupZipkin() error {
 	if err != nil {
 		log.Warningf("build Zipkin endpoint found err: %v", err)
 	}
-	tracer, err := zipkin.NewTracer(reporter, zipkin.WithLocalEndpoint(recorder))
+	tracer, err := zipkin.NewTracer(
+		reporter,
+		zipkin.WithLocalEndpoint(recorder),
+	)
 	if err != nil {
 		return err
 	}
@@ -100,7 +111,7 @@ func (t *trace) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg)
 	}
 
 	req := request.Request{W: w, Req: r}
-	span = t.Tracer().StartSpan(spanName(ctx, req))
+	span = t.Tracer().StartSpan(defaultTopLevelSpanName)
 	defer span.Finish()
 
 	rw := dnstest.NewRecorder(w)
@@ -115,7 +126,3 @@ func (t *trace) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg)
 
 	return status, err
 }
-
-func spanName(ctx context.Context, req request.Request) string {
-	return "servedns:" + metrics.WithServer(ctx) + " " + req.Name()
-}

plugin/trace/trace_test.go

@@ -79,9 +79,10 @@ func TestTrace(t *testing.T) {
 
 			rootSpan := fs[1]
 			req := request.Request{W: w, Req: tc.question}
-			if rootSpan.OperationName != spanName(ctx, req) {
-				t.Errorf("Unexpected span name: rootSpan.Name: want %v, got %v", spanName(ctx, req), rootSpan.OperationName)
+			if rootSpan.OperationName != defaultTopLevelSpanName {
+				t.Errorf("Unexpected span name: rootSpan.Name: want %v, got %v", defaultTopLevelSpanName, rootSpan.OperationName)
 			}
+
 			if rootSpan.Tag(tagName) != req.Name() {
 				t.Errorf("Unexpected span tag: rootSpan.Tag(%v): want %v, got %v", tagName, req.Name(), rootSpan.Tag(tagName))
 			}