Upgraded DataDog tracing library to 1.14.0

Gopkg.lock

@@ -1864,7 +1864,7 @@
   version = "v1.20.1"
 
 [[projects]]
-  digest = "1:b886012746f19e2a7c6c3901ea9f86e8a5e32ff2b4407086f4f3181269976957"
+  digest = "1:b49eceff862a3048ec28dad1fce40bcbdc1703119dbad35d7e5f1beb4f9a4527"
   name = "gopkg.in/DataDog/dd-trace-go.v1"
   packages = [
     "ddtrace",
@@ -1872,10 +1872,11 @@
     "ddtrace/internal",
     "ddtrace/opentracer",
     "ddtrace/tracer",
+    "internal/globalconfig",
   ]
   pruneopts = "NUT"
-  revision = "7fb2bce4b1ed6ab61f7a9e1be30dea56de19db7c"
-  version = "v1.8.0"
+  revision = "c19e9e56d5b5b71b6507ce1b0ec06d85aa3705a1"
+  version = "v1.14.0"
 
 [[projects]]
   digest = "1:c970218a20933dd0a2eb2006de922217fa9276f57d25009b2a934eb1c50031cc"
@@ -2287,6 +2288,7 @@
     "github.com/opentracing/opentracing-go/log",
     "github.com/openzipkin-contrib/zipkin-go-opentracing",
     "github.com/patrickmn/go-cache",
+    "github.com/pmezard/go-difflib/difflib",
     "github.com/prometheus/client_golang/prometheus",
     "github.com/prometheus/client_golang/prometheus/promhttp",
     "github.com/prometheus/client_model/go",

Gopkg.toml

@@ -285,7 +285,7 @@ required = [
 
 [[constraint]]
   name = "gopkg.in/DataDog/dd-trace-go.v1"
-  version = "1.7.0"
+  version = "1.13.0"
 
 [[constraint]]
   name = "github.com/instana/go-sensor"

vendor/gopkg.in/DataDog/dd-trace-go.v1/ddtrace/ddtrace.go

@@ -91,6 +91,12 @@ type FinishConfig struct {
 
 	// NoDebugStack will prevent any set errors from generating an attached stack trace tag.
 	NoDebugStack bool
+
+	// StackFrames specifies the number of stack frames to be attached in spans that finish with errors.
+	StackFrames uint
+
+	// SkipStackFrames specifies the offset at which to start reporting stack frames from the stack.
+	SkipStackFrames uint
 }
 
 // StartSpanConfig holds the configuration for starting a new span. It is usually passed
@@ -108,4 +114,8 @@ type StartSpanConfig struct {
 	// Tags holds a set of key/value pairs that should be set as metadata on the
 	// new span.
 	Tags map[string]interface{}
+
+	// Force-set the SpanID, rather than use a random number. If no Parent SpanContext is present,
+	// then this will also set the TraceID to the same value.
+	SpanID uint64
 }

vendor/gopkg.in/DataDog/dd-trace-go.v1/ddtrace/ext/tags.go

@@ -27,10 +27,15 @@ const (
 	// HTTPURL sets the HTTP URL for a span.
 	HTTPURL = "http.url"
 
-	// TODO: In the next major version, suffix these constants (SpanType, etc)
-	// with "*Key" (SpanTypeKey, etc) to more easily differentiate between
+	// TODO: In the next major version, prefix these constants (SpanType, etc)
+	// with "Key*" (KeySpanType, etc) to more easily differentiate between
 	// constants representing tag values and constants representing keys.
 
+	// SpanName is a pseudo-key for setting a span's operation name by means of
+	// a tag. It is mostly here to facilitate vendor-agnostic frameworks like Opentracing
+	// and OpenCensus.
+	SpanName = "span.name"
+
 	// SpanType defines the Span type (web, db, cache).
 	SpanType = "span.type"
 
@@ -54,4 +59,20 @@ const (
 
 	// Environment specifies the environment to use with a trace.
 	Environment = "env"
+
+	// EventSampleRate specifies the rate at which this span will be sampled
+	// as an APM event.
+	EventSampleRate = "_dd1.sr.eausr"
+
+	// AnalyticsEvent specifies whether the span should be recorded as a Trace
+	// Search & Analytics event.
+	AnalyticsEvent = "analytics.event"
+
+	// ManualKeep is a tag which specifies that the trace to which this span
+	// belongs to should be kept when set to true.
+	ManualKeep = "manual.keep"
+
+	// ManualDrop is a tag which specifies that the trace to which this span
+	// belongs to should be dropped when set to true.
+	ManualDrop = "manual.drop"
 )

vendor/gopkg.in/DataDog/dd-trace-go.v1/ddtrace/opentracer/option.go

@@ -18,6 +18,11 @@ func ResourceName(name string) opentracing.StartSpanOption {
 	return opentracing.Tag{Key: ext.ResourceName, Value: name}
 }
 
+// SpanName sets the Datadog operation name for the span.
+func SpanName(name string) opentracing.StartSpanOption {
+	return opentracing.Tag{Key: ext.SpanName, Value: name}
+}
+
 // SpanType can be used with opentracing.StartSpan to set the type of a span.
 func SpanType(name string) opentracing.StartSpanOption {
 	return opentracing.Tag{Key: ext.SpanType, Value: name}

vendor/gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer/option.go

@@ -1,6 +1,7 @@
 package tracer
 
 import (
+	"log"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -8,6 +9,7 @@ import (
 
 	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace"
 	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/ext"
+	"gopkg.in/DataDog/dd-trace-go.v1/internal/globalconfig"
 )
 
 // config holds the tracer configuration.
@@ -21,7 +23,7 @@ type config struct {
 	// sampler specifies the sampler that will be used for sampling traces.
 	sampler Sampler
 
-	// agentAddr specifies the hostname and  of the agent where the traces
+	// agentAddr specifies the hostname and port of the agent where the traces
 	// are sent to.
 	agentAddr string
 
@@ -37,6 +39,10 @@ type config struct {
 
 	// httpRoundTripper defines the http.RoundTripper used by the agent transport.
 	httpRoundTripper http.RoundTripper
+
+	// hostname is automatically assigned when the DD_TRACE_REPORT_HOSTNAME is set to true,
+	// and is added as a special tag to the root span of traces.
+	hostname string
 }
 
 // StartOption represents a function that can be provided as a parameter to Start.
@@ -47,6 +53,14 @@ func defaults(c *config) {
 	c.serviceName = filepath.Base(os.Args[0])
 	c.sampler = NewAllSampler()
 	c.agentAddr = defaultAddress
+
+	if os.Getenv("DD_TRACE_REPORT_HOSTNAME") == "true" {
+		var err error
+		c.hostname, err = os.Hostname()
+		if err != nil {
+			log.Printf("%sunable to look up hostname: %v\n", errorPrefix, err)
+		}
+	}
 }
 
 // WithPrioritySampling is deprecated, and priority sampling is enabled by default.
@@ -117,6 +131,22 @@ func WithHTTPRoundTripper(r http.RoundTripper) StartOption {
 	}
 }
 
+// WithAnalytics allows specifying whether Trace Search & Analytics should be enabled
+// for integrations.
+func WithAnalytics(on bool) StartOption {
+	if on {
+		return WithAnalyticsRate(1.0)
+	}
+	return WithAnalyticsRate(0.0)
+}
+
+// WithAnalyticsRate sets the global sampling rate for sampling APM events.
+func WithAnalyticsRate(rate float64) StartOption {
+	return func(_ *config) {
+		globalconfig.SetAnalyticsRate(rate)
+	}
+}
+
 // StartSpanOption is a configuration option for StartSpan. It is aliased in order
 // to help godoc group all the functions returning it together. It is considered
 // more correct to refer to it as the type as the origin, ddtrace.StartSpanOption.
@@ -149,6 +179,15 @@ func SpanType(name string) StartSpanOption {
 	return Tag(ext.SpanType, name)
 }
 
+// WithSpanID sets the SpanID on the started span, instead of using a random number.
+// If there is no parent Span (eg from ChildOf), then the TraceID will also be set to the
+// value given here.
+func WithSpanID(id uint64) StartSpanOption {
+	return func(cfg *ddtrace.StartSpanConfig) {
+		cfg.SpanID = id
+	}
+}
+
 // ChildOf tells StartSpan to use the given span context as a parent for the
 // created span.
 func ChildOf(ctx ddtrace.SpanContext) StartSpanOption {
@@ -179,7 +218,8 @@ func FinishTime(t time.Time) FinishOption {
 }
 
 // WithError marks the span as having had an error. It uses the information from
-// err to set tags such as the error message, error type and stack trace.
+// err to set tags such as the error message, error type and stack trace. It has
+// no effect if the error is nil.
 func WithError(err error) FinishOption {
 	return func(cfg *ddtrace.FinishConfig) {
 		cfg.Error = err
@@ -194,3 +234,14 @@ func NoDebugStack() FinishOption {
 		cfg.NoDebugStack = true
 	}
 }
+
+// StackFrames limits the number of stack frames included into erroneous spans to n, starting from skip.
+func StackFrames(n, skip uint) FinishOption {
+	if n == 0 {
+		return NoDebugStack()
+	}
+	return func(cfg *ddtrace.FinishConfig) {
+		cfg.StackFrames = n
+		cfg.SkipStackFrames = skip
+	}
+}

vendor/gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer/sampler.go

@@ -140,5 +140,5 @@ func (ps *prioritySampler) apply(spn *span) {
 	} else {
 		spn.SetTag(ext.SamplingPriority, ext.PriorityAutoReject)
 	}
-	spn.SetTag(samplingPriorityRateKey, rate)
+	spn.SetTag(keySamplingPriorityRate, rate)
 }

vendor/gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer/span.go

@@ -5,7 +5,9 @@ package tracer
 import (
 	"fmt"
 	"reflect"
+	"runtime"
 	"runtime/debug"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -30,6 +32,13 @@ var (
 	_ msgp.Decodable = (*spanLists)(nil)
 )
 
+// errorConfig holds customization options for setting error tags.
+type errorConfig struct {
+	noDebugStack bool
+	stackFrames  uint
+	stackSkip    uint
+}
+
 // span represents a computation. Callers must call Finish when a span is
 // complete to ensure it's submitted.
 type span struct {
@@ -80,8 +89,13 @@ func (s *span) SetTag(key string, value interface{}) {
 	if s.finished {
 		return
 	}
-	if key == ext.Error {
-		s.setTagError(value, true)
+	switch key {
+	case ext.Error:
+		s.setTagError(value, &errorConfig{})
+		return
+	}
+	if v, ok := value.(bool); ok {
+		s.setTagBool(key, v)
 		return
 	}
 	if v, ok := value.(string); ok {
@@ -99,7 +113,7 @@ func (s *span) SetTag(key string, value interface{}) {
 
 // setTagError sets the error tag. It accounts for various valid scenarios.
 // This method is not safe for concurrent use.
-func (s *span) setTagError(value interface{}, debugStack bool) {
+func (s *span) setTagError(value interface{}, cfg *errorConfig) {
 	if s.finished {
 		return
 	}
@@ -117,8 +131,12 @@ func (s *span) setTagError(value interface{}, debugStack bool) {
 		s.Error = 1
 		s.Meta[ext.ErrorMsg] = v.Error()
 		s.Meta[ext.ErrorType] = reflect.TypeOf(v).String()
-		if debugStack {
-			s.Meta[ext.ErrorStack] = string(debug.Stack())
+		if !cfg.noDebugStack {
+			if cfg.stackFrames == 0 {
+				s.Meta[ext.ErrorStack] = string(debug.Stack())
+			} else {
+				s.Meta[ext.ErrorStack] = takeStacktrace(cfg.stackFrames, cfg.stackSkip)
+			}
 		}
 	case nil:
 		// no error
@@ -130,9 +148,40 @@ func (s *span) setTagError(value interface{}, debugStack bool) {
 	}
 }
 
+// takeStacktrace takes stacktrace
+func takeStacktrace(n, skip uint) string {
+	var builder strings.Builder
+	pcs := make([]uintptr, n)
+
+	// +2 to exclude runtime.Callers and takeStacktrace
+	numFrames := runtime.Callers(2+int(skip), pcs)
+	if numFrames == 0 {
+		return ""
+	}
+	frames := runtime.CallersFrames(pcs[:numFrames])
+	for i := 0; ; i++ {
+		frame, more := frames.Next()
+		if i != 0 {
+			builder.WriteByte('\n')
+		}
+		builder.WriteString(frame.Function)
+		builder.WriteByte('\n')
+		builder.WriteByte('\t')
+		builder.WriteString(frame.File)
+		builder.WriteByte(':')
+		builder.WriteString(strconv.Itoa(frame.Line))
+		if !more {
+			break
+		}
+	}
+	return builder.String()
+}
+
 // setTagString sets a string tag. This method is not safe for concurrent use.
 func (s *span) setTagString(key, v string) {
 	switch key {
+	case ext.SpanName:
+		s.Name = v
 	case ext.ServiceName:
 		s.Service = v
 	case ext.ResourceName:
@@ -144,13 +193,39 @@ func (s *span) setTagString(key, v string) {
 	}
 }
 
+// setTagBool sets a boolean tag on the span.
+func (s *span) setTagBool(key string, v bool) {
+	switch key {
+	case ext.AnalyticsEvent:
+		if v {
+			s.setTagNumeric(ext.EventSampleRate, 1.0)
+		} else {
+			s.setTagNumeric(ext.EventSampleRate, 0.0)
+		}
+	case ext.ManualDrop:
+		if v {
+			s.setTagNumeric(ext.SamplingPriority, ext.PriorityUserReject)
+		}
+	case ext.ManualKeep:
+		if v {
+			s.setTagNumeric(ext.SamplingPriority, ext.PriorityUserKeep)
+		}
+	default:
+		if v {
+			s.setTagString(key, "true")
+		} else {
+			s.setTagString(key, "false")
+		}
+	}
+}
+
 // setTagNumeric sets a numeric tag, in our case called a metric. This method
 // is not safe for concurrent use.
 func (s *span) setTagNumeric(key string, v float64) {
 	switch key {
 	case ext.SamplingPriority:
 		// setting sampling priority per spec
-		s.Metrics[samplingPriorityKey] = v
+		s.Metrics[keySamplingPriority] = v
 		s.context.setSamplingPriority(int(v))
 	default:
 		s.Metrics[key] = v
@@ -172,7 +247,11 @@ func (s *span) Finish(opts ...ddtrace.FinishOption) {
 	}
 	if cfg.Error != nil {
 		s.Lock()
-		s.setTagError(cfg.Error, !cfg.NoDebugStack)
+		s.setTagError(cfg.Error, &errorConfig{
+			noDebugStack: cfg.NoDebugStack,
+			stackFrames:  cfg.StackFrames,
+			stackSkip:    cfg.SkipStackFrames,
+		})
 		s.Unlock()
 	}
 	s.finish(t)
@@ -236,6 +315,8 @@ func (s *span) String() string {
 }
 
 const (
-	samplingPriorityKey     = "_sampling_priority_v1"
-	samplingPriorityRateKey = "_sampling_priority_rate_v1"
+	keySamplingPriority     = "_sampling_priority_v1"
+	keySamplingPriorityRate = "_sampling_priority_rate_v1"
+	keyOrigin               = "_dd.origin"
+	keyHostname             = "_dd.hostname"
 )

vendor/gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer/spancontext.go

@@ -25,10 +25,9 @@ type spanContext struct {
 	traceID uint64
 	spanID  uint64
 
-	mu          sync.RWMutex // guards below fields
-	baggage     map[string]string
-	priority    int
-	hasPriority bool
+	mu      sync.RWMutex // guards below fields
+	baggage map[string]string
+	origin  string // e.g. "synthetics"
 }
 
 // newSpanContext creates a new SpanContext to serve as context for the given
@@ -42,15 +41,10 @@ func newSpanContext(span *span, parent *spanContext) *spanContext {
 		spanID:  span.SpanID,
 		span:    span,
 	}
-	if v, ok := span.Metrics[samplingPriorityKey]; ok {
-		context.hasPriority = true
-		context.priority = int(v)
-	}
 	if parent != nil {
 		context.trace = parent.trace
 		context.drop = parent.drop
-		context.hasPriority = parent.hasSamplingPriority()
-		context.priority = parent.samplingPriority()
+		context.origin = parent.origin
 		parent.ForeachBaggageItem(func(k, v string) bool {
 			context.setBaggageItem(k, v)
 			return true
@@ -59,6 +53,10 @@ func newSpanContext(span *span, parent *spanContext) *spanContext {
 	if context.trace == nil {
 		context.trace = newTrace()
 	}
+	if context.trace.root == nil {
+		// first span in the trace can safely be assumed to be the root
+		context.trace.root = span
+	}
 	// put span in context's trace
 	context.trace.push(span)
 	return context
@@ -82,22 +80,21 @@ func (c *spanContext) ForeachBaggageItem(handler func(k, v string) bool) {
 }
 
 func (c *spanContext) setSamplingPriority(p int) {
-	c.mu.Lock()
-	defer c.mu.Unlock()
-	c.priority = p
-	c.hasPriority = true
+	if c.trace == nil {
+		c.trace = newTrace()
+	}
+	c.trace.setSamplingPriority(float64(p))
 }
 
 func (c *spanContext) samplingPriority() int {
-	c.mu.RLock()
-	defer c.mu.RUnlock()
-	return c.priority
+	if c.trace == nil {
+		return 0
+	}
+	return c.trace.samplingPriority()
 }
 
 func (c *spanContext) hasSamplingPriority() bool {
-	c.mu.RLock()
-	defer c.mu.RUnlock()
-	return c.hasPriority
+	return c.trace != nil && c.trace.hasSamplingPriority()
 }
 
 func (c *spanContext) setBaggageItem(key, val string) {
@@ -116,15 +113,23 @@ func (c *spanContext) baggageItem(key string) string {
 }
 
 // finish marks this span as finished in the trace.
-func (c *spanContext) finish() { c.trace.ackFinish() }
+func (c *spanContext) finish() { c.trace.finishedOne(c.span) }
 
-// trace holds information about a specific trace. This structure is shared
-// between all spans in a trace.
+// trace contains shared context information about a trace, such as sampling
+// priority, the root reference and a buffer of the spans which are part of the
+// trace, if these exist.
 type trace struct {
 	mu       sync.RWMutex // guards below fields
 	spans    []*span      // all the spans that are part of this trace
 	finished int          // the number of finished spans
 	full     bool         // signifies that the span buffer is full
+	priority *float64     // sampling priority
+	locked   bool         // specifies if the sampling priority can be altered
+
+	// root specifies the root of the trace, if known; it is nil when a span
+	// context is extracted from a carrier, at which point there are no spans in
+	// the trace yet.
+	root *span
 }
 
 var (
@@ -146,6 +151,42 @@ func newTrace() *trace {
 	return &trace{spans: make([]*span, 0, traceStartSize)}
 }
 
+func (t *trace) hasSamplingPriority() bool {
+	t.mu.RLock()
+	defer t.mu.RUnlock()
+	return t.priority != nil
+}
+
+func (t *trace) samplingPriority() int {
+	t.mu.RLock()
+	defer t.mu.RUnlock()
+	if t.priority == nil {
+		return 0
+	}
+	return int(*t.priority)
+}
+
+func (t *trace) setSamplingPriority(p float64) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.setSamplingPriorityLocked(p)
+}
+
+func (t *trace) setSamplingPriorityLocked(p float64) {
+	if t.locked {
+		return
+	}
+	if t.root == nil {
+		// this trace is distributed (no local root); modifications
+		// to the sampling priority are not allowed.
+		t.locked = true
+	}
+	if t.priority == nil {
+		t.priority = new(float64)
+	}
+	*t.priority = p
+}
+
 // push pushes a new span into the trace. If the buffer is full, it returns
 // a errBufferFull error.
 func (t *trace) push(sp *span) {
@@ -164,12 +205,16 @@ func (t *trace) push(sp *span) {
 		}
 		return
 	}
+	if v, ok := sp.Metrics[keySamplingPriority]; ok {
+		t.setSamplingPriorityLocked(v)
+	}
 	t.spans = append(t.spans, sp)
 }
 
-// ackFinish aknowledges that another span in the trace has finished, and checks
-// if the trace is complete, in which case it calls the onFinish function.
-func (t *trace) ackFinish() {
+// finishedOne aknowledges that another span in the trace has finished, and checks
+// if the trace is complete, in which case it calls the onFinish function. It uses
+// the given priority, if non-nil, to mark the root span.
+func (t *trace) finishedOne(s *span) {
 	t.mu.Lock()
 	defer t.mu.Unlock()
 	if t.full {
@@ -180,6 +225,13 @@ func (t *trace) ackFinish() {
 		return
 	}
 	t.finished++
+	if s == t.root && t.priority != nil {
+		// after the root has finished we lock down the priority;
+		// we won't be able to make changes to a span after finishing
+		// without causing a race condition.
+		t.root.Metrics[keySamplingPriority] = *t.priority
+		t.locked = true
+	}
 	if len(t.spans) != t.finished {
 		return
 	}

vendor/gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer/textmap.go

@@ -2,10 +2,12 @@ package tracer
 
 import (
 	"net/http"
+	"os"
 	"strconv"
 	"strings"
 
 	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace"
+	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/ext"
 )
 
 // HTTPHeadersCarrier wraps an http.Header as a TextMapWriter and TextMapReader, allowing
@@ -54,6 +56,11 @@ func (c TextMapCarrier) ForeachKey(handler func(key, val string) error) error {
 	return nil
 }
 
+const (
+	headerPropagationStyleInject  = "DD_PROPAGATION_STYLE_INJECT"
+	headerPropagationStyleExtract = "DD_PROPAGATION_STYLE_EXTRACT"
+)
+
 const (
 	// DefaultBaggageHeaderPrefix specifies the prefix that will be used in
 	// HTTP headers or text maps to prefix baggage keys.
@@ -72,6 +79,10 @@ const (
 	DefaultPriorityHeader = "x-datadog-sampling-priority"
 )
 
+// originHeader specifies the name of the header indicating the origin of the trace.
+// It is used with the Synthetics product and usually has the value "synthetics".
+const originHeader = "x-datadog-origin"
+
 // PropagatorConfig defines the configuration for initializing a propagator.
 type PropagatorConfig struct {
 	// BaggagePrefix specifies the prefix that will be used to store baggage
@@ -110,21 +121,86 @@ func NewPropagator(cfg *PropagatorConfig) Propagator {
 	if cfg.PriorityHeader == "" {
 		cfg.PriorityHeader = DefaultPriorityHeader
 	}
-	return &propagator{cfg}
+	return &chainedPropagator{
+		injectors:  getPropagators(cfg, headerPropagationStyleInject),
+		extractors: getPropagators(cfg, headerPropagationStyleExtract),
+	}
 }
 
-// propagator implements a propagator which uses TextMap internally.
-// It propagates the trace and span IDs, as well as the baggage from the
-// context.
-type propagator struct{ cfg *PropagatorConfig }
+// chainedPropagator implements Propagator and applies a list of injectors and extractors.
+// When injecting, all injectors are called to propagate the span context.
+// When extracting, it tries each extractor, selecting the first successful one.
+type chainedPropagator struct {
+	injectors  []Propagator
+	extractors []Propagator
+}
+
+// getPropagators returns a list of propagators based on the list found in the
+// given environment variable. If the list doesn't contain a value or has invalid
+// values, the default propagator will be returned.
+func getPropagators(cfg *PropagatorConfig, env string) []Propagator {
+	dd := &propagator{cfg}
+	ps := os.Getenv(env)
+	if ps == "" {
+		return []Propagator{dd}
+	}
+	var list []Propagator
+	for _, v := range strings.Split(ps, ",") {
+		switch strings.ToLower(v) {
+		case "datadog":
+			list = append(list, dd)
+		case "b3":
+			list = append(list, &propagatorB3{})
+		default:
+			// TODO(cgilmour): consider logging something for invalid/unknown styles.
+		}
+	}
+	if len(list) == 0 {
+		// return the default
+		return []Propagator{dd}
+	}
+	return list
+}
 
 // Inject defines the Propagator to propagate SpanContext data
 // out of the current process. The implementation propagates the
 // TraceID and the current active SpanID, as well as the Span baggage.
+func (p *chainedPropagator) Inject(spanCtx ddtrace.SpanContext, carrier interface{}) error {
+	for _, v := range p.injectors {
+		err := v.Inject(spanCtx, carrier)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Extract implements Propagator.
+func (p *chainedPropagator) Extract(carrier interface{}) (ddtrace.SpanContext, error) {
+	for _, v := range p.extractors {
+		ctx, err := v.Extract(carrier)
+		if ctx != nil {
+			// first extractor returns
+			return ctx, nil
+		}
+		if err == ErrSpanContextNotFound {
+			continue
+		}
+		return nil, err
+	}
+	return nil, ErrSpanContextNotFound
+}
+
+// propagator implements Propagator and injects/extracts span contexts
+// using datadog headers. Only TextMap carriers are supported.
+type propagator struct {
+	cfg *PropagatorConfig
+}
+
 func (p *propagator) Inject(spanCtx ddtrace.SpanContext, carrier interface{}) error {
-	switch v := carrier.(type) {
+	switch c := carrier.(type) {
 	case TextMapWriter:
-		return p.injectTextMap(spanCtx, v)
+		return p.injectTextMap(spanCtx, c)
 	default:
 		return ErrInvalidCarrier
 	}
@@ -141,6 +217,9 @@ func (p *propagator) injectTextMap(spanCtx ddtrace.SpanContext, writer TextMapWr
 	if ctx.hasSamplingPriority() {
 		writer.Set(p.cfg.PriorityHeader, strconv.Itoa(ctx.samplingPriority()))
 	}
+	if ctx.origin != "" {
+		writer.Set(originHeader, ctx.origin)
+	}
 	// propagate OpenTracing baggage
 	for k, v := range ctx.baggage {
 		writer.Set(p.cfg.BaggagePrefix+k, v)
@@ -148,11 +227,10 @@ func (p *propagator) injectTextMap(spanCtx ddtrace.SpanContext, writer TextMapWr
 	return nil
 }
 
-// Extract implements Propagator.
 func (p *propagator) Extract(carrier interface{}) (ddtrace.SpanContext, error) {
-	switch v := carrier.(type) {
+	switch c := carrier.(type) {
 	case TextMapReader:
-		return p.extractTextMap(v)
+		return p.extractTextMap(c)
 	default:
 		return nil, ErrInvalidCarrier
 	}
@@ -180,6 +258,8 @@ func (p *propagator) extractTextMap(reader TextMapReader) (ddtrace.SpanContext,
 				return ErrSpanContextCorrupted
 			}
 			ctx.setSamplingPriority(priority)
+		case originHeader:
+			ctx.origin = v
 		default:
 			if strings.HasPrefix(key, p.cfg.BaggagePrefix) {
 				ctx.setBaggageItem(strings.TrimPrefix(key, p.cfg.BaggagePrefix), v)
@@ -195,3 +275,83 @@ func (p *propagator) extractTextMap(reader TextMapReader) (ddtrace.SpanContext,
 	}
 	return &ctx, nil
 }
+
+const (
+	b3TraceIDHeader = "x-b3-traceid"
+	b3SpanIDHeader  = "x-b3-spanid"
+	b3SampledHeader = "x-b3-sampled"
+)
+
+// propagatorB3 implements Propagator and injects/extracts span contexts
+// using B3 headers. Only TextMap carriers are supported.
+type propagatorB3 struct{}
+
+func (p *propagatorB3) Inject(spanCtx ddtrace.SpanContext, carrier interface{}) error {
+	switch c := carrier.(type) {
+	case TextMapWriter:
+		return p.injectTextMap(spanCtx, c)
+	default:
+		return ErrInvalidCarrier
+	}
+}
+
+func (*propagatorB3) injectTextMap(spanCtx ddtrace.SpanContext, writer TextMapWriter) error {
+	ctx, ok := spanCtx.(*spanContext)
+	if !ok || ctx.traceID == 0 || ctx.spanID == 0 {
+		return ErrInvalidSpanContext
+	}
+	writer.Set(b3TraceIDHeader, strconv.FormatUint(ctx.traceID, 16))
+	writer.Set(b3SpanIDHeader, strconv.FormatUint(ctx.spanID, 16))
+	if ctx.hasSamplingPriority() {
+		if ctx.samplingPriority() >= ext.PriorityAutoKeep {
+			writer.Set(b3SampledHeader, "1")
+		} else {
+			writer.Set(b3SampledHeader, "0")
+		}
+	}
+	return nil
+}
+
+func (p *propagatorB3) Extract(carrier interface{}) (ddtrace.SpanContext, error) {
+	switch c := carrier.(type) {
+	case TextMapReader:
+		return p.extractTextMap(c)
+	default:
+		return nil, ErrInvalidCarrier
+	}
+}
+
+func (*propagatorB3) extractTextMap(reader TextMapReader) (ddtrace.SpanContext, error) {
+	var ctx spanContext
+	err := reader.ForeachKey(func(k, v string) error {
+		var err error
+		key := strings.ToLower(k)
+		switch key {
+		case b3TraceIDHeader:
+			ctx.traceID, err = strconv.ParseUint(v, 16, 64)
+			if err != nil {
+				return ErrSpanContextCorrupted
+			}
+		case b3SpanIDHeader:
+			ctx.spanID, err = strconv.ParseUint(v, 16, 64)
+			if err != nil {
+				return ErrSpanContextCorrupted
+			}
+		case b3SampledHeader:
+			priority, err := strconv.Atoi(v)
+			if err != nil {
+				return ErrSpanContextCorrupted
+			}
+			ctx.setSamplingPriority(priority)
+		default:
+		}
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	if ctx.traceID == 0 || ctx.spanID == 0 {
+		return nil, ErrSpanContextNotFound
+	}
+	return &ctx, nil
+}

vendor/gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer/tracer.go

@@ -44,6 +44,8 @@ type tracer struct {
 
 	// prioritySampling holds an instance of the priority sampler.
 	prioritySampling *prioritySampler
+	// pid of the process
+	pid string
 }
 
 const (
@@ -131,6 +133,7 @@ func newTracer(opts ...StartOption) *tracer {
 		errorBuffer:      make(chan error, errorBufferSize),
 		stopped:          make(chan struct{}),
 		prioritySampling: newPrioritySampler(),
+		pid:              strconv.Itoa(os.Getpid()),
 	}
 
 	go t.worker()
@@ -230,7 +233,10 @@ func (t *tracer) StartSpan(operationName string, options ...ddtrace.StartSpanOpt
 			context = ctx
 		}
 	}
-	id := random.Uint64()
+	id := opts.SpanID
+	if id == 0 {
+		id = random.Uint64()
+	}
 	// span defaults
 	span := &span{
 		Name:     operationName,
@@ -248,19 +254,28 @@ func (t *tracer) StartSpan(operationName string, options ...ddtrace.StartSpanOpt
 		span.TraceID = context.traceID
 		span.ParentID = context.spanID
 		if context.hasSamplingPriority() {
-			span.Metrics[samplingPriorityKey] = float64(context.samplingPriority())
+			span.Metrics[keySamplingPriority] = float64(context.samplingPriority())
 		}
 		if context.span != nil {
-			// it has a local parent, inherit the service
+			// local parent, inherit service
 			context.span.RLock()
 			span.Service = context.span.Service
 			context.span.RUnlock()
+		} else {
+			// remote parent
+			if context.origin != "" {
+				// mark origin
+				span.Meta[keyOrigin] = context.origin
+			}
 		}
 	}
 	span.context = newSpanContext(span, context)
 	if context == nil || context.span == nil {
 		// this is either a root span or it has a remote parent, we should add the PID.
-		span.SetTag(ext.Pid, strconv.Itoa(os.Getpid()))
+		span.SetTag(ext.Pid, t.pid)
+		if t.hostname != "" {
+			span.SetTag(keyHostname, t.hostname)
+		}
 	}
 	// add tags from options
 	for k, v := range opts.Tags {
@@ -361,7 +376,7 @@ const sampleRateMetricKey = "_sample_rate"
 
 // Sample samples a span with the internal sampler.
 func (t *tracer) sample(span *span) {
-	if span.context.hasPriority {
+	if span.context.hasSamplingPriority() {
 		// sampling decision was already made
 		return
 	}

vendor/gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer/transport.go

@@ -15,7 +15,7 @@ import (
 var (
 	// TODO(gbbr): find a more effective way to keep this up to date,
 	// e.g. via `go generate`
-	tracerVersion = "v1.7.0"
+	tracerVersion = "v1.13.1"
 
 	// We copy the transport to avoid using the default one, as it might be
 	// augmented with tracing and we don't want these calls to be recorded.

vendor/gopkg.in/DataDog/dd-trace-go.v1/internal/globalconfig/globalconfig.go

@@ -0,0 +1,28 @@
+// Package globalconfig stores configuration which applies globally to both the tracer
+// and integrations.
+package globalconfig
+
+import "sync"
+
+var cfg = &config{}
+
+type config struct {
+	mu            sync.RWMutex
+	analyticsRate float64
+}
+
+// AnalyticsRate returns the sampling rate at which events should be marked. It uses
+// synchronizing mechanisms, meaning that for optimal performance it's best to read it
+// once and store it.
+func AnalyticsRate() float64 {
+	cfg.mu.RLock()
+	defer cfg.mu.RUnlock()
+	return cfg.analyticsRate
+}
+
+// SetAnalyticsRate sets the given event sampling rate globally.
+func SetAnalyticsRate(rate float64) {
+	cfg.mu.Lock()
+	cfg.analyticsRate = rate
+	cfg.mu.Unlock()
+}