Added support for Haystack tracing

pkg/tracing/haystack/haystack.go

@@ -0,0 +1,63 @@
+package haystack
+
+import (
+	"io"
+	"strings"
+	"time"
+
+	"github.com/ExpediaDotCom/haystack-client-go"
+	"github.com/containous/traefik/pkg/log"
+	"github.com/opentracing/opentracing-go"
+)
+
+// Name sets the name of this tracer
+const Name = "haystack"
+
+// Config provides configuration settings for a haystack tracer
+type Config struct {
+	LocalAgentHost          string `description:"Set haystack-agent's host that the reporter will used. Defaults to localhost" export:"false"`
+	LocalAgentPort          int    `description:"Set haystack-agent's port that the reporter will used. Defaults to 35000" export:"false"`
+	GlobalTag               string `description:"Key:Value tag to be set on all the spans." export:"true"`
+	TraceIDHeaderName       string `description:"Specifies the header name that will be used to store the trace ID.." export:"true"`
+	ParentIDHeaderName      string `description:"Specifies the header name that will be used to store the parent ID." export:"true"`
+	SpanIDHeaderName        string `description:"Specifies the header name that will be used to store the span ID." export:"true"`
+	BaggagePrefixHeaderName string `description:"specifies the header name prefix that will be used to store baggage items in a map." export:"true"`
+}
+
+// Setup sets up the tracer
+func (c *Config) Setup(serviceName string) (opentracing.Tracer, io.Closer, error) {
+	tag := strings.SplitN(c.GlobalTag, ":", 2)
+
+	value := ""
+	if len(tag) == 2 {
+		value = tag[1]
+	}
+
+	host := "localhost"
+	port := 35000
+	if len(c.LocalAgentHost) > 0 {
+		host = c.LocalAgentHost
+	}
+	if c.LocalAgentPort > 0 {
+		port = c.LocalAgentPort
+	}
+
+	tracer, closer := haystack.NewTracer(serviceName, haystack.NewAgentDispatcher(host, port, 3*time.Second, 1000),
+		haystack.TracerOptionsFactory.Tag(tag[0], value),
+		haystack.TracerOptionsFactory.Propagator(opentracing.HTTPHeaders,
+			haystack.NewTextMapPropagator(haystack.PropagatorOpts{
+				TraceIDKEYName:       c.TraceIDHeaderName,
+				ParentSpanIDKEYName:  c.ParentIDHeaderName,
+				SpanIDKEYName:        c.SpanIDHeaderName,
+				BaggagePrefixKEYName: c.BaggagePrefixHeaderName,
+			}, haystack.DefaultCodex{})),
+		haystack.TracerOptionsFactory.Logger(&haystackLogger{logger: log.WithoutContext()}),
+	)
+
+	// Without this, child spans are getting the NOOP tracer
+	opentracing.SetGlobalTracer(tracer)
+
+	log.WithoutContext().Debug("DataDog tracer configured")
+
+	return tracer, closer, nil
+}