add history trace command

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

util/otelutil/jaeger.go

@@ -0,0 +1,45 @@
+package otelutil
+
+import (
+	"fmt"
+
+	"github.com/docker/buildx/util/otelutil/jaeger"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/sdk/resource"
+)
+
+type JaegerData struct {
+	Data []jaeger.Trace `json:"data"`
+}
+
+// JaegerData return Jaeger data compatible with ui import feature.
+// https://github.com/jaegertracing/jaeger-ui/issues/381#issuecomment-494150826
+func (s Spans) JaegerData() JaegerData {
+	roSpans := s.ReadOnlySpans()
+
+	// fetch default service.name from default resource for backup
+	var defaultServiceName string
+	defaultResource := resource.Default()
+	if value, exists := defaultResource.Set().Value(attribute.Key("service.name")); exists {
+		defaultServiceName = value.AsString()
+	}
+
+	data := jaeger.Trace{
+		TraceID:   jaeger.TraceID(roSpans[0].SpanContext().TraceID().String()),
+		Processes: make(map[jaeger.ProcessID]jaeger.Process),
+		Spans:     []jaeger.Span{},
+	}
+	for i := range roSpans {
+		ss := roSpans[i]
+		pid := jaeger.ProcessID(fmt.Sprintf("p%d", i))
+		data.Processes[pid] = jaeger.ResourceToProcess(ss.Resource(), defaultServiceName)
+		span := jaeger.ConvertSpan(ss)
+		span.Process = nil
+		span.ProcessID = pid
+		data.Spans = append(data.Spans, span)
+	}
+
+	return JaegerData{
+		Data: []jaeger.Trace{data},
+	}
+}

util/otelutil/jaeger/convert.go

@@ -0,0 +1,224 @@
+package jaeger
+
+import (
+	"encoding/json"
+	"time"
+
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/codes"
+	"go.opentelemetry.io/otel/sdk/resource"
+	tracesdk "go.opentelemetry.io/otel/sdk/trace"
+	"go.opentelemetry.io/otel/trace"
+)
+
+const (
+	keyInstrumentationLibraryName    = "otel.library.name"
+	keyInstrumentationLibraryVersion = "otel.library.version"
+	keyError                         = "error"
+	keySpanKind                      = "span.kind"
+	keyStatusCode                    = "otel.status_code"
+	keyStatusMessage                 = "otel.status_description"
+	keyDroppedAttributeCount         = "otel.event.dropped_attributes_count"
+	keyEventName                     = "event"
+)
+
+func ResourceToProcess(res *resource.Resource, defaultServiceName string) Process {
+	var process Process
+	var serviceName attribute.KeyValue
+	if res != nil {
+		for iter := res.Iter(); iter.Next(); {
+			if iter.Attribute().Key == attribute.Key("service.name") {
+				serviceName = iter.Attribute()
+				// Don't convert service.name into tag.
+				continue
+			}
+			if tag := keyValueToJaegerTag(iter.Attribute()); tag != nil {
+				process.Tags = append(process.Tags, *tag)
+			}
+		}
+	}
+
+	// If no service.name is contained in a Span's Resource,
+	// that field MUST be populated from the default Resource.
+	if serviceName.Value.AsString() == "" {
+		serviceName = attribute.Key("service.version").String(defaultServiceName)
+	}
+	process.ServiceName = serviceName.Value.AsString()
+
+	return process
+}
+
+func ConvertSpan(ss tracesdk.ReadOnlySpan) Span {
+	attr := ss.Attributes()
+	tags := make([]KeyValue, 0, len(attr))
+	for _, kv := range attr {
+		tag := keyValueToJaegerTag(kv)
+		if tag != nil {
+			tags = append(tags, *tag)
+		}
+	}
+
+	if is := ss.InstrumentationScope(); is.Name != "" {
+		tags = append(tags, getStringTag(keyInstrumentationLibraryName, is.Name))
+		if is.Version != "" {
+			tags = append(tags, getStringTag(keyInstrumentationLibraryVersion, is.Version))
+		}
+	}
+
+	if ss.SpanKind() != trace.SpanKindInternal {
+		tags = append(tags,
+			getStringTag(keySpanKind, ss.SpanKind().String()),
+		)
+	}
+
+	if ss.Status().Code != codes.Unset {
+		switch ss.Status().Code {
+		case codes.Ok:
+			tags = append(tags, getStringTag(keyStatusCode, "OK"))
+		case codes.Error:
+			tags = append(tags, getBoolTag(keyError, true))
+			tags = append(tags, getStringTag(keyStatusCode, "ERROR"))
+		}
+		if ss.Status().Description != "" {
+			tags = append(tags, getStringTag(keyStatusMessage, ss.Status().Description))
+		}
+	}
+
+	var logs []Log
+	for _, a := range ss.Events() {
+		nTags := len(a.Attributes)
+		if a.Name != "" {
+			nTags++
+		}
+		if a.DroppedAttributeCount != 0 {
+			nTags++
+		}
+		fields := make([]KeyValue, 0, nTags)
+		if a.Name != "" {
+			// If an event contains an attribute with the same key, it needs
+			// to be given precedence and overwrite this.
+			fields = append(fields, getStringTag(keyEventName, a.Name))
+		}
+		for _, kv := range a.Attributes {
+			tag := keyValueToJaegerTag(kv)
+			if tag != nil {
+				fields = append(fields, *tag)
+			}
+		}
+		if a.DroppedAttributeCount != 0 {
+			fields = append(fields, getInt64Tag(keyDroppedAttributeCount, int64(a.DroppedAttributeCount)))
+		}
+		logs = append(logs, Log{
+			Timestamp: timeAsEpochMicroseconds(a.Time),
+			Fields:    fields,
+		})
+	}
+
+	var refs []Reference
+	for _, link := range ss.Links() {
+		refs = append(refs, Reference{
+			RefType: FollowsFrom,
+			TraceID: TraceID(link.SpanContext.TraceID().String()),
+			SpanID:  SpanID(link.SpanContext.SpanID().String()),
+		})
+	}
+	refs = append(refs, Reference{
+		RefType: ChildOf,
+		TraceID: TraceID(ss.Parent().TraceID().String()),
+		SpanID:  SpanID(ss.Parent().SpanID().String()),
+	})
+
+	return Span{
+		TraceID:       TraceID(ss.SpanContext().TraceID().String()),
+		SpanID:        SpanID(ss.SpanContext().SpanID().String()),
+		Flags:         uint32(ss.SpanContext().TraceFlags()),
+		OperationName: ss.Name(),
+		References:    refs,
+		StartTime:     timeAsEpochMicroseconds(ss.StartTime()),
+		Duration:      durationAsMicroseconds(ss.EndTime().Sub(ss.StartTime())),
+		Tags:          tags,
+		Logs:          logs,
+	}
+}
+
+func keyValueToJaegerTag(keyValue attribute.KeyValue) *KeyValue {
+	var tag *KeyValue
+	switch keyValue.Value.Type() {
+	case attribute.STRING:
+		s := keyValue.Value.AsString()
+		tag = &KeyValue{
+			Key:   string(keyValue.Key),
+			Type:  StringType,
+			Value: s,
+		}
+	case attribute.BOOL:
+		b := keyValue.Value.AsBool()
+		tag = &KeyValue{
+			Key:   string(keyValue.Key),
+			Type:  BoolType,
+			Value: b,
+		}
+	case attribute.INT64:
+		i := keyValue.Value.AsInt64()
+		tag = &KeyValue{
+			Key:   string(keyValue.Key),
+			Type:  Int64Type,
+			Value: i,
+		}
+	case attribute.FLOAT64:
+		f := keyValue.Value.AsFloat64()
+		tag = &KeyValue{
+			Key:   string(keyValue.Key),
+			Type:  Float64Type,
+			Value: f,
+		}
+	case attribute.BOOLSLICE,
+		attribute.INT64SLICE,
+		attribute.FLOAT64SLICE,
+		attribute.STRINGSLICE:
+		data, _ := json.Marshal(keyValue.Value.AsInterface())
+		a := (string)(data)
+		tag = &KeyValue{
+			Key:   string(keyValue.Key),
+			Type:  StringType,
+			Value: a,
+		}
+	}
+	return tag
+}
+
+func getInt64Tag(k string, i int64) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Type:  Int64Type,
+		Value: i,
+	}
+}
+
+func getStringTag(k, s string) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Type:  StringType,
+		Value: s,
+	}
+}
+
+func getBoolTag(k string, b bool) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Type:  BoolType,
+		Value: b,
+	}
+}
+
+// timeAsEpochMicroseconds converts time.Time to microseconds since epoch,
+// which is the format the StartTime field is stored in the Span.
+func timeAsEpochMicroseconds(t time.Time) uint64 {
+	return uint64(t.UnixNano() / 1000)
+}
+
+// durationAsMicroseconds converts time.Duration to microseconds,
+// which is the format the Duration field is stored in the Span.
+func durationAsMicroseconds(d time.Duration) uint64 {
+	return uint64(d.Nanoseconds() / 1000)
+}

util/otelutil/jaeger/model.go

@@ -0,0 +1,102 @@
+package jaeger
+
+// ReferenceType is the reference type of one span to another
+type ReferenceType string
+
+// TraceID is the shared trace ID of all spans in the trace.
+type TraceID string
+
+// SpanID is the id of a span
+type SpanID string
+
+// ProcessID is a hashed value of the Process struct that is unique within the trace.
+type ProcessID string
+
+// ValueType is the type of a value stored in KeyValue struct.
+type ValueType string
+
+const (
+	// ChildOf means a span is the child of another span
+	ChildOf ReferenceType = "CHILD_OF"
+	// FollowsFrom means a span follows from another span
+	FollowsFrom ReferenceType = "FOLLOWS_FROM"
+
+	// StringType indicates a string value stored in KeyValue
+	StringType ValueType = "string"
+	// BoolType indicates a Boolean value stored in KeyValue
+	BoolType ValueType = "bool"
+	// Int64Type indicates a 64bit signed integer value stored in KeyValue
+	Int64Type ValueType = "int64"
+	// Float64Type indicates a 64bit float value stored in KeyValue
+	Float64Type ValueType = "float64"
+	// BinaryType indicates an arbitrary byte array stored in KeyValue
+	BinaryType ValueType = "binary"
+)
+
+// Trace is a list of spans
+type Trace struct {
+	TraceID   TraceID               `json:"traceID"`
+	Spans     []Span                `json:"spans"`
+	Processes map[ProcessID]Process `json:"processes"`
+	Warnings  []string              `json:"warnings"`
+}
+
+// Span is a span denoting a piece of work in some infrastructure
+// When converting to UI model, ParentSpanID and Process should be dereferenced into
+// References and ProcessID, respectively.
+// When converting to ES model, ProcessID and Warnings should be omitted. Even if
+// included, ES with dynamic settings off will automatically ignore unneeded fields.
+type Span struct {
+	TraceID       TraceID     `json:"traceID"`
+	SpanID        SpanID      `json:"spanID"`
+	ParentSpanID  SpanID      `json:"parentSpanID,omitempty"` // deprecated
+	Flags         uint32      `json:"flags,omitempty"`
+	OperationName string      `json:"operationName"`
+	References    []Reference `json:"references"`
+	StartTime     uint64      `json:"startTime"` // microseconds since Unix epoch
+	Duration      uint64      `json:"duration"`  // microseconds
+	Tags          []KeyValue  `json:"tags"`
+	Logs          []Log       `json:"logs"`
+	ProcessID     ProcessID   `json:"processID,omitempty"`
+	Process       *Process    `json:"process,omitempty"`
+	Warnings      []string    `json:"warnings"`
+}
+
+// Reference is a reference from one span to another
+type Reference struct {
+	RefType ReferenceType `json:"refType"`
+	TraceID TraceID       `json:"traceID"`
+	SpanID  SpanID        `json:"spanID"`
+}
+
+// Process is the process emitting a set of spans
+type Process struct {
+	ServiceName string     `json:"serviceName"`
+	Tags        []KeyValue `json:"tags"`
+}
+
+// Log is a log emitted in a span
+type Log struct {
+	Timestamp uint64     `json:"timestamp"`
+	Fields    []KeyValue `json:"fields"`
+}
+
+// KeyValue is a key-value pair with typed value.
+type KeyValue struct {
+	Key   string      `json:"key"`
+	Type  ValueType   `json:"type,omitempty"`
+	Value interface{} `json:"value"`
+}
+
+// DependencyLink shows dependencies between services
+type DependencyLink struct {
+	Parent    string `json:"parent"`
+	Child     string `json:"child"`
+	CallCount uint64 `json:"callCount"`
+}
+
+// Operation defines the data in the operation response when query operation by service and span kind
+type Operation struct {
+	Name     string `json:"name"`
+	SpanKind string `json:"spanKind"`
+}

util/otelutil/jaeger_test.go

@@ -0,0 +1,27 @@
+package otelutil
+
+import (
+	"bytes"
+	"encoding/json"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+const jaegerFixture = "./fixtures/jaeger.json"
+
+func TestJaegerData(t *testing.T) {
+	dt, err := os.ReadFile(bktracesFixture)
+	require.NoError(t, err)
+
+	spanStubs, err := ParseSpanStubs(bytes.NewReader(dt))
+	require.NoError(t, err)
+
+	trace := spanStubs.JaegerData()
+	dtJaegerTrace, err := json.MarshalIndent(trace, "", "  ")
+	require.NoError(t, err)
+	dtJaeger, err := os.ReadFile(jaegerFixture)
+	require.NoError(t, err)
+	require.Equal(t, string(dtJaeger), string(dtJaegerTrace))
+}

util/otelutil/span.go

@@ -0,0 +1,491 @@
+package otelutil
+
+import (
+	"bytes"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"io"
+	"reflect"
+	"time"
+
+	"github.com/pkg/errors"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/sdk/instrumentation"
+	"go.opentelemetry.io/otel/sdk/resource"
+	tracesdk "go.opentelemetry.io/otel/sdk/trace"
+	"go.opentelemetry.io/otel/trace"
+)
+
+// Span is a type similar to otel's SpanStub, but with the correct types needed
+// for handle marshaling and unmarshalling.
+type Span struct {
+	// Name is the name of a specific span
+	Name string
+	// SpanContext is the unique SpanContext that identifies the span
+	SpanContext trace.SpanContext
+	// Parten is the unique SpanContext that identifies the parent of the span.
+	// If the span has no parent, this span context will be invalid.
+	Parent trace.SpanContext
+	// SpanKind is the role the span plays in a Trace
+	SpanKind trace.SpanKind
+	// StartTime is the time the span started recording
+	StartTime time.Time
+	// EndTime returns the time the span stopped recording
+	EndTime time.Time
+	// Attributes are the defining attributes of a span
+	Attributes []attribute.KeyValue
+	// Events are all the events that occurred within the span
+	Events []tracesdk.Event
+	// Links are all the links the span has to other spans
+	Links []tracesdk.Link
+	// Status is that span status
+	Status tracesdk.Status
+	// DroppedAttributes is the number of attributes dropped by the span due to
+	// a limit being reached
+	DroppedAttributes int
+	// DroppedEvents is the number of attributes dropped by the span due to a
+	// limit being reached
+	DroppedEvents int
+	// DroppedLinks is the number of links dropped by the span due to a limit
+	// being reached
+	DroppedLinks int
+	// ChildSpanCount is the count of spans that consider the span a direct
+	// parent
+	ChildSpanCount int
+	// Resource is the information about the entity that produced the span
+	// We have to change this type from the otel type to make this struct
+	// marshallable
+	Resource []attribute.KeyValue
+	// InstrumentationLibrary is information about the library that produced
+	// the span
+	//nolint:staticcheck
+	InstrumentationLibrary instrumentation.Library
+}
+
+type Spans []Span
+
+// Len return the length of the Spans.
+func (s Spans) Len() int {
+	return len(s)
+}
+
+// ReadOnlySpans return a list of tracesdk.ReadOnlySpan from span stubs.
+func (s Spans) ReadOnlySpans() []tracesdk.ReadOnlySpan {
+	roSpans := make([]tracesdk.ReadOnlySpan, len(s))
+	for i := range s {
+		roSpans[i] = s[i].Snapshot()
+	}
+	return roSpans
+}
+
+// ParseSpanStubs parses BuildKit trace data into a list of SpanStubs.
+func ParseSpanStubs(rdr io.Reader) (Spans, error) {
+	var spanStubs []Span
+	decoder := json.NewDecoder(rdr)
+	for {
+		var span Span
+		if err := decoder.Decode(&span); err == io.EOF {
+			break
+		} else if err != nil {
+			return nil, errors.Wrapf(err, "error decoding JSON")
+		}
+		spanStubs = append(spanStubs, span)
+	}
+	return spanStubs, nil
+}
+
+// spanData is data that we need to unmarshal in custom ways.
+type spanData struct {
+	Name              string
+	SpanContext       spanContext
+	Parent            spanContext
+	SpanKind          trace.SpanKind
+	StartTime         time.Time
+	EndTime           time.Time
+	Attributes        []keyValue
+	Events            []event
+	Links             []link
+	Status            tracesdk.Status
+	DroppedAttributes int
+	DroppedEvents     int
+	DroppedLinks      int
+	ChildSpanCount    int
+	Resource          []keyValue // change this type from the otel type to make this struct marshallable
+	//nolint:staticcheck
+	InstrumentationLibrary instrumentation.Library
+}
+
+// spanContext is a custom type used to unmarshal otel SpanContext correctly.
+type spanContext struct {
+	TraceID    string
+	SpanID     string
+	TraceFlags string
+	TraceState string // TODO: implement, currently dropped
+	Remote     bool
+}
+
+// event is a custom type used to unmarshal otel Event correctly.
+type event struct {
+	Name                  string
+	Attributes            []keyValue
+	DroppedAttributeCount int
+	Time                  time.Time
+}
+
+// link is a custom type used to unmarshal otel Link correctly.
+type link struct {
+	SpanContext           spanContext
+	Attributes            []keyValue
+	DroppedAttributeCount int
+}
+
+// keyValue is a custom type used to unmarshal otel KeyValue correctly.
+type keyValue struct {
+	Key   string
+	Value value
+}
+
+// value is a custom type used to unmarshal otel Value correctly.
+type value struct {
+	Type  string
+	Value interface{}
+}
+
+// UnmarshalJSON implements json.Unmarshaler for Span which allows correctly
+// retrieving attribute.KeyValue values.
+func (s *Span) UnmarshalJSON(data []byte) error {
+	var sd spanData
+	if err := json.NewDecoder(bytes.NewReader(data)).Decode(&sd); err != nil {
+		return errors.Wrap(err, "unable to decode to spanData")
+	}
+
+	s.Name = sd.Name
+	s.SpanKind = sd.SpanKind
+	s.StartTime = sd.StartTime
+	s.EndTime = sd.EndTime
+	s.Status = sd.Status
+	s.DroppedAttributes = sd.DroppedAttributes
+	s.DroppedEvents = sd.DroppedEvents
+	s.DroppedLinks = sd.DroppedLinks
+	s.ChildSpanCount = sd.ChildSpanCount
+	s.InstrumentationLibrary = sd.InstrumentationLibrary
+
+	spanCtx, err := sd.SpanContext.asTraceSpanContext()
+	if err != nil {
+		return errors.Wrap(err, "unable to decode spanCtx")
+	}
+	s.SpanContext = spanCtx
+
+	parent, err := sd.Parent.asTraceSpanContext()
+	if err != nil {
+		return errors.Wrap(err, "unable to decode parent")
+	}
+	s.Parent = parent
+
+	var attributes []attribute.KeyValue
+	for _, a := range sd.Attributes {
+		kv, err := a.asAttributeKeyValue()
+		if err != nil {
+			return errors.Wrapf(err, "unable to decode attribute (%s)", a.Key)
+		}
+		attributes = append(attributes, kv)
+	}
+	s.Attributes = attributes
+
+	var events []tracesdk.Event
+	for _, e := range sd.Events {
+		var eventAttributes []attribute.KeyValue
+		for _, a := range e.Attributes {
+			kv, err := a.asAttributeKeyValue()
+			if err != nil {
+				return errors.Wrapf(err, "unable to decode event attribute (%s)", a.Key)
+			}
+			eventAttributes = append(eventAttributes, kv)
+		}
+		events = append(events, tracesdk.Event{
+			Name:                  e.Name,
+			Attributes:            eventAttributes,
+			DroppedAttributeCount: e.DroppedAttributeCount,
+			Time:                  e.Time,
+		})
+	}
+	s.Events = events
+
+	var links []tracesdk.Link
+	for _, l := range sd.Links {
+		linkSpanCtx, err := l.SpanContext.asTraceSpanContext()
+		if err != nil {
+			return errors.Wrap(err, "unable to decode linkSpanCtx")
+		}
+		var linkAttributes []attribute.KeyValue
+		for _, a := range l.Attributes {
+			kv, err := a.asAttributeKeyValue()
+			if err != nil {
+				return errors.Wrapf(err, "unable to decode link attribute (%s)", a.Key)
+			}
+			linkAttributes = append(linkAttributes, kv)
+		}
+		links = append(links, tracesdk.Link{
+			SpanContext:           linkSpanCtx,
+			Attributes:            linkAttributes,
+			DroppedAttributeCount: l.DroppedAttributeCount,
+		})
+	}
+	s.Links = links
+
+	var resources []attribute.KeyValue
+	for _, r := range sd.Resource {
+		kv, err := r.asAttributeKeyValue()
+		if err != nil {
+			return errors.Wrapf(err, "unable to decode resource (%s)", r.Key)
+		}
+		resources = append(resources, kv)
+	}
+	s.Resource = resources
+
+	return nil
+}
+
+// asTraceSpanContext converts the internal spanContext representation to an
+// otel one.
+func (sc *spanContext) asTraceSpanContext() (trace.SpanContext, error) {
+	traceID, err := traceIDFromHex(sc.TraceID)
+	if err != nil {
+		return trace.SpanContext{}, errors.Wrap(err, "unable to parse trace id")
+	}
+	spanID, err := spanIDFromHex(sc.SpanID)
+	if err != nil {
+		return trace.SpanContext{}, errors.Wrap(err, "unable to parse span id")
+	}
+	traceFlags := trace.TraceFlags(0x00)
+	if sc.TraceFlags == "01" {
+		traceFlags = trace.TraceFlags(0x01)
+	}
+	config := trace.SpanContextConfig{
+		TraceID:    traceID,
+		SpanID:     spanID,
+		TraceFlags: traceFlags,
+		Remote:     sc.Remote,
+	}
+	return trace.NewSpanContext(config), nil
+}
+
+// asAttributeKeyValue converts the internal keyValue representation to an
+// otel one.
+func (kv *keyValue) asAttributeKeyValue() (attribute.KeyValue, error) {
+	// value types get encoded as string
+	switch kv.Value.Type {
+	case attribute.INVALID.String():
+		return attribute.KeyValue{}, errors.New("invalid value type")
+	case attribute.BOOL.String():
+		return attribute.Bool(kv.Key, kv.Value.Value.(bool)), nil
+	case attribute.INT64.String():
+		// value could be int64 or float64, so handle both cases (float64 comes
+		// from json unmarshal)
+		var v int64
+		switch i := kv.Value.Value.(type) {
+		case int64:
+			v = i
+		case float64:
+			v = int64(i)
+		}
+		return attribute.Int64(kv.Key, v), nil
+	case attribute.FLOAT64.String():
+		return attribute.Float64(kv.Key, kv.Value.Value.(float64)), nil
+	case attribute.STRING.String():
+		return attribute.String(kv.Key, kv.Value.Value.(string)), nil
+	case attribute.BOOLSLICE.String():
+		return attribute.BoolSlice(kv.Key, kv.Value.Value.([]bool)), nil
+	case attribute.INT64SLICE.String():
+		// handle both float64 and int64 (float64 comes from json unmarshal)
+		var v []int64
+		switch sli := kv.Value.Value.(type) {
+		case []int64:
+			v = sli
+		case []float64:
+			for i := range sli {
+				v = append(v, int64(sli[i]))
+			}
+		}
+		return attribute.Int64Slice(kv.Key, v), nil
+	case attribute.FLOAT64SLICE.String():
+		return attribute.Float64Slice(kv.Key, kv.Value.Value.([]float64)), nil
+	case attribute.STRINGSLICE.String():
+		var strSli []string
+		// sometimes we can get an []interface{} instead of a []string, so
+		// always cast to []string if that happens.
+		switch sli := kv.Value.Value.(type) {
+		case []string:
+			strSli = sli
+		case []interface{}:
+			for i := range sli {
+				var v string
+				// best case we have a string, otherwise, cast it using
+				// fmt.Sprintf
+				if str, ok := sli[i].(string); ok {
+					v = str
+				} else {
+					v = fmt.Sprintf("%v", sli[i])
+				}
+				// add the string to the slice
+				strSli = append(strSli, v)
+			}
+		default:
+			return attribute.KeyValue{}, errors.Errorf("got unsupported type %q for %s", reflect.ValueOf(kv.Value.Value).Kind(), attribute.STRINGSLICE.String())
+		}
+		return attribute.StringSlice(kv.Key, strSli), nil
+	default:
+		return attribute.KeyValue{}, errors.Errorf("unknown value type %s", kv.Value.Type)
+	}
+}
+
+// traceIDFromHex returns a TraceID from a hex string if it is compliant with
+// the W3C trace-context specification and removes the validity check.
+// https://www.w3.org/TR/trace-context/#trace-id
+func traceIDFromHex(h string) (trace.TraceID, error) {
+	t := trace.TraceID{}
+	if len(h) != 32 {
+		return t, errors.New("unable to parse trace id")
+	}
+	if err := decodeHex(h, t[:]); err != nil {
+		return t, err
+	}
+	return t, nil
+}
+
+// spanIDFromHex returns a SpanID from a hex string if it is compliant with the
+// W3C trace-context specification and removes the validity check.
+// https://www.w3.org/TR/trace-context/#parent-id
+func spanIDFromHex(h string) (trace.SpanID, error) {
+	s := trace.SpanID{}
+	if len(h) != 16 {
+		return s, errors.New("unable to parse span id of length: %d")
+	}
+	if err := decodeHex(h, s[:]); err != nil {
+		return s, err
+	}
+	return s, nil
+}
+
+// decodeHex decodes hex in a manner compliant with otel.
+func decodeHex(h string, b []byte) error {
+	for _, r := range h {
+		switch {
+		case 'a' <= r && r <= 'f':
+			continue
+		case '0' <= r && r <= '9':
+			continue
+		default:
+			return errors.New("unable to parse hex id")
+		}
+	}
+	decoded, err := hex.DecodeString(h)
+	if err != nil {
+		return err
+	}
+	copy(b, decoded)
+	return nil
+}
+
+// Snapshot turns a Span into a ReadOnlySpan which is exportable by otel.
+func (s *Span) Snapshot() tracesdk.ReadOnlySpan {
+	return spanSnapshot{
+		name:                 s.Name,
+		spanContext:          s.SpanContext,
+		parent:               s.Parent,
+		spanKind:             s.SpanKind,
+		startTime:            s.StartTime,
+		endTime:              s.EndTime,
+		attributes:           s.Attributes,
+		events:               s.Events,
+		links:                s.Links,
+		status:               s.Status,
+		droppedAttributes:    s.DroppedAttributes,
+		droppedEvents:        s.DroppedEvents,
+		droppedLinks:         s.DroppedLinks,
+		childSpanCount:       s.ChildSpanCount,
+		resource:             resource.NewSchemaless(s.Resource...),
+		instrumentationScope: s.InstrumentationLibrary,
+	}
+}
+
+// spanSnapshot is a helper type for transforming a Span into a ReadOnlySpan.
+type spanSnapshot struct {
+	// Embed the interface to implement the private method.
+	tracesdk.ReadOnlySpan
+
+	name                 string
+	spanContext          trace.SpanContext
+	parent               trace.SpanContext
+	spanKind             trace.SpanKind
+	startTime            time.Time
+	endTime              time.Time
+	attributes           []attribute.KeyValue
+	events               []tracesdk.Event
+	links                []tracesdk.Link
+	status               tracesdk.Status
+	droppedAttributes    int
+	droppedEvents        int
+	droppedLinks         int
+	childSpanCount       int
+	resource             *resource.Resource
+	instrumentationScope instrumentation.Scope
+}
+
+// Name returns the Name of the snapshot
+func (s spanSnapshot) Name() string { return s.name }
+
+// SpanContext returns the SpanContext of the snapshot
+func (s spanSnapshot) SpanContext() trace.SpanContext { return s.spanContext }
+
+// Parent returns the Parent of the snapshot
+func (s spanSnapshot) Parent() trace.SpanContext { return s.parent }
+
+// SpanKind returns the SpanKind of the snapshot
+func (s spanSnapshot) SpanKind() trace.SpanKind { return s.spanKind }
+
+// StartTime returns the StartTime of the snapshot
+func (s spanSnapshot) StartTime() time.Time { return s.startTime }
+
+// EndTime returns the EndTime of the snapshot
+func (s spanSnapshot) EndTime() time.Time { return s.endTime }
+
+// Attributes returns the Attributes of the snapshot
+func (s spanSnapshot) Attributes() []attribute.KeyValue { return s.attributes }
+
+// Links returns the Links of the snapshot
+func (s spanSnapshot) Links() []tracesdk.Link { return s.links }
+
+// Events return the Events of the snapshot
+func (s spanSnapshot) Events() []tracesdk.Event { return s.events }
+
+// Status returns the Status of the snapshot
+func (s spanSnapshot) Status() tracesdk.Status { return s.status }
+
+// DroppedAttributes returns the DroppedAttributes of the snapshot
+func (s spanSnapshot) DroppedAttributes() int { return s.droppedAttributes }
+
+// DroppedLinks returns the DroppedLinks of the snapshot
+func (s spanSnapshot) DroppedLinks() int { return s.droppedLinks }
+
+// DroppedEvents returns the DroppedEvents of the snapshot
+func (s spanSnapshot) DroppedEvents() int { return s.droppedEvents }
+
+// ChildSpanCount returns the ChildSpanCount of the snapshot
+func (s spanSnapshot) ChildSpanCount() int { return s.childSpanCount }
+
+// Resource returns the Resource of the snapshot
+func (s spanSnapshot) Resource() *resource.Resource { return s.resource }
+
+// InstrumentationScope returns the InstrumentationScope of the snapshot
+func (s spanSnapshot) InstrumentationScope() instrumentation.Scope {
+	return s.instrumentationScope
+}
+
+// InstrumentationLibrary returns the InstrumentationLibrary of the snapshot
+//
+//nolint:staticcheck
+func (s spanSnapshot) InstrumentationLibrary() instrumentation.Library {
+	return s.instrumentationScope
+}

util/otelutil/span_test.go

@@ -0,0 +1,159 @@
+package otelutil
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/exporters/stdout/stdouttrace"
+)
+
+// curl -s --unix-socket /tmp/docker-desktop-build-dev.sock http://localhost/blobs/default/default?digest=sha256:3103104e9fa908087bd47572da6ad9a5a7bf973608f736536d18d635a7da0140 -X GET > ./fixtures/bktraces.json
+const bktracesFixture = "./fixtures/bktraces.json"
+
+const otlpFixture = "./fixtures/otlp.json"
+
+func TestParseSpanStubs(t *testing.T) {
+	dt, err := os.ReadFile(bktracesFixture)
+	require.NoError(t, err)
+
+	spanStubs, err := ParseSpanStubs(bytes.NewReader(dt))
+	require.NoError(t, err)
+	require.Equal(t, 73, len(spanStubs))
+
+	dtSpanStubs, err := json.MarshalIndent(spanStubs, "", "  ")
+	require.NoError(t, err)
+	dtotel, err := os.ReadFile(otlpFixture)
+	require.NoError(t, err)
+	require.Equal(t, string(dtotel), string(dtSpanStubs))
+
+	exp, err := stdouttrace.New(stdouttrace.WithPrettyPrint())
+	require.NoError(t, err)
+	require.NoError(t, exp.ExportSpans(context.Background(), spanStubs.ReadOnlySpans()))
+}
+
+func TestAsAttributeKeyValue(t *testing.T) {
+	type args struct {
+		Type  string
+		value any
+	}
+	tests := []struct {
+		name string
+		args args
+		want attribute.KeyValue
+	}{
+		{
+			name: "string",
+			args: args{
+				Type:  attribute.STRING.String(),
+				value: "value",
+			},
+			want: attribute.String("key", "value"),
+		},
+		{
+			name: "int64 (int64)",
+			args: args{
+				Type:  attribute.INT64.String(),
+				value: int64(1),
+			},
+			want: attribute.Int64("key", 1),
+		},
+		{
+			name: "int64 (float64)",
+			args: args{
+				Type:  attribute.INT64.String(),
+				value: float64(1.0),
+			},
+			want: attribute.Int64("key", 1),
+		},
+		{
+			name: "bool",
+			args: args{
+				Type:  attribute.BOOL.String(),
+				value: true,
+			},
+			want: attribute.Bool("key", true),
+		},
+		{
+			name: "float64",
+			args: args{
+				Type:  attribute.FLOAT64.String(),
+				value: float64(1.0),
+			},
+			want: attribute.Float64("key", 1.0),
+		},
+		{
+			name: "float64slice",
+			args: args{
+				Type:  attribute.FLOAT64SLICE.String(),
+				value: []float64{1.0, 2.0},
+			},
+			want: attribute.Float64Slice("key", []float64{1.0, 2.0}),
+		},
+		{
+			name: "int64slice (int64)",
+			args: args{
+				Type:  attribute.INT64SLICE.String(),
+				value: []int64{1, 2},
+			},
+			want: attribute.Int64Slice("key", []int64{1, 2}),
+		},
+		{
+			name: "int64slice (float64)",
+			args: args{
+				Type:  attribute.INT64SLICE.String(),
+				value: []float64{1.0, 2.0},
+			},
+			want: attribute.Int64Slice("key", []int64{1, 2}),
+		},
+		{
+			name: "boolslice",
+			args: args{
+				Type:  attribute.BOOLSLICE.String(),
+				value: []bool{true, false},
+			},
+			want: attribute.BoolSlice("key", []bool{true, false}),
+		},
+		{
+			name: "stringslice (strings)",
+			args: args{
+				Type:  attribute.STRINGSLICE.String(),
+				value: []string{"value1", "value2"},
+			},
+			want: attribute.StringSlice("key", []string{"value1", "value2"}),
+		},
+		{
+			name: "stringslice (interface of string)",
+			args: args{
+				Type:  attribute.STRINGSLICE.String(),
+				value: []interface{}{"value1", "value2"},
+			},
+			want: attribute.StringSlice("key", []string{"value1", "value2"}),
+		},
+		{
+			name: "stringslice (interface mixed)",
+			args: args{
+				Type:  attribute.STRINGSLICE.String(),
+				value: []interface{}{"value1", 2},
+			},
+			want: attribute.StringSlice("key", []string{"value1", "2"}),
+		},
+	}
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			kv := keyValue{
+				Key:   "key",
+				Value: value{Type: tt.args.Type, Value: tt.args.value},
+			}
+			attr, err := kv.asAttributeKeyValue()
+			require.NoError(t, err, "failed to convert key value to attribute key value")
+			assert.Equal(t, tt.want, attr, "attribute key value mismatch")
+		})
+	}
+}