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kurochan/datadog.go

Created December 4, 2024 15:25
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Datadog APMのtrace contextをmedia playlistに埋める
Raw
datadog.go
package datadog
import (
"bytes"
"encoding/base64"
"encoding/binary"
"fmt"
"strings"
"time"
"github.com/grafov/m3u8"
"gopkg.in/DataDog/dd-trace-go.v1/ddtrace"
"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
)
const tagName = "#EXT-X-DATERANGE"
const idPrefix = "trace-"
const className = "trace-context"
const attributePrefix = "X-TRACE-"
type HLSSpanContext struct {
SpanContext ddtrace.SpanContext
StartDate time.Time
attributes tracer.TextMapCarrier
}
func NewHLSSpanContext(ctx ddtrace.SpanContext, startDate time.Time) (*HLSSpanContext, error) {
attributes := tracer.TextMapCarrier(map[string]string{})
if err := tracer.Inject(ctx, attributes); err != nil {
return nil, err
}
return &HLSSpanContext{
SpanContext: ctx,
StartDate: startDate,
attributes: attributes,
}, nil
}
// m3u8.CustomTag
func (h *HLSSpanContext) TagName() string {
return tagName
}
// m3u8.CustomTag
func (h *HLSSpanContext) Encode() *bytes.Buffer {
var b bytes.Buffer
b.Write([]byte(h.String()))
return &b
}
// m3u8.CustomTag
func (h *HLSSpanContext) String() string {
b := make([]byte, 0, 16)
b = binary.LittleEndian.AppendUint64(b, h.SpanContext.TraceID())
b = binary.LittleEndian.AppendUint64(b, h.SpanContext.SpanID())
id := idPrefix + base64.RawStdEncoding.EncodeToString(b)
class := className
startDate := h.StartDate.Format(time.RFC3339)
attributes := make([]string, 0, 3+len(h.attributes))
attributes = append(
attributes,
"ID="+"\""+id+"\"",
"CLASS="+"\""+class+"\"",
"START-DATE="+"\""+startDate+"\"",
)
for k, v := range h.attributes {
attributes = append(attributes, attributePrefix+k+"="+"\""+v+"\"")
}
return tagName + ":" + strings.Join(attributes, ",")
}
type HLSSpanDecoder struct {
}
// m3u8.CustomDecoder
func (d *HLSSpanDecoder) TagName() string {
return tagName
}
// m3u8.CustomDecoder
func (d *HLSSpanDecoder) Decode(line string) (m3u8.CustomTag, error) {
if !strings.HasPrefix(line, tagName+":") {
return nil, fmt.Errorf("invalid tag name: %s", line)
}
kv, err := parseAttributes(line)
if err != nil {
return nil, err
}
var class string
var startDate time.Time
textMap := tracer.TextMapCarrier(make(map[string]string))
for k, v := range kv {
switch k {
case "CLASS":
class = v
case "START-DATE":
t, err := time.Parse(time.RFC3339, v)
if err != nil {
return nil, err
}
startDate = t
default:
if strings.HasPrefix(k, attributePrefix) {
k = strings.TrimPrefix(k, attributePrefix)
textMap[k] = v
}
}
}
if class != className {
return nil, fmt.Errorf("invalid class: %s", class)
}
spanContext, err := tracer.Extract(textMap)
if err != nil {
return nil, err
}
h, err := NewHLSSpanContext(spanContext, startDate)
if err != nil {
return nil, err
}
return h, nil
}
// m3u8.CustomDecoder
func (d *HLSSpanDecoder) SegmentTag() bool {
return true
}
func parseAttributes(line string) (map[string]string, error) {
line = strings.TrimPrefix(line, tagName+":")
runes := []rune(line)
attributes := make([]string, 0, 4)
quoted := false
split := false
start := 0
for i, r := range runes {
switch {
case split:
split = false
attributes = append(attributes, string(runes[start:i-1]))
start = i
case r == '"':
quoted = !quoted
continue
case r == ',' && !quoted:
split = true
}
}
attributes = append(attributes, string(runes[start:]))
textMap := make(map[string]string)
for _, attribute := range attributes {
kv := strings.Split(attribute, "=")
if len(kv) < 2 {
return nil, fmt.Errorf("invalid attribute: %s", attribute)
}
v := strings.Join(kv[1:], "=")
v = strings.TrimPrefix(v, "\"")
v = strings.TrimSuffix(v, "\"")
textMap[kv[0]] = v
}
return textMap, nil
}
Raw
datadog_test.go
package datadog
import (
"testing"
"time"
"github.com/stretchr/testify/assert"
"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/mocktracer"
"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
)
func TestEncodeHLSSpanContext(t *testing.T) {
mt := mocktracer.Start()
defer mt.Stop()
ts, err := time.Parse(time.RFC3339, "2024-01-02T15:00:01Z")
assert.NoError(t, err)
span := tracer.StartSpan("test-span", tracer.WithSpanID(100))
assert.NotNil(t, span.Context())
h, err := NewHLSSpanContext(span.Context(), ts)
assert.NoError(t, err)
tag := h.String()
assert.NotNil(t, tag)
assert.Contains(t, []string{
`#EXT-X-DATERANGE:ID="trace-ZAAAAAAAAABkAAAAAAAAAA",CLASS="trace-context",START-DATE="2024-01-02T15:00:01Z",X-TRACE-x-datadog-trace-id="100",X-TRACE-x-datadog-parent-id="100"`,
`#EXT-X-DATERANGE:ID="trace-ZAAAAAAAAABkAAAAAAAAAA",CLASS="trace-context",START-DATE="2024-01-02T15:00:01Z",X-TRACE-x-datadog-parent-id="100",X-TRACE-x-datadog-trace-id="100"`,
}, tag)
}
func TestDecodeHLSSpanContext(t *testing.T) {
mt := mocktracer.Start()
defer mt.Stop()
m3u8 := `#EXT-X-DATERANGE:ID="trace-vds3qcWHqGPD4B6WKOv7IA",CLASS="trace-context",START-DATE="2024-10-28T16:17:37+09:00",X-TRACE-x-datadog-sampling-priority="1",X-TRACE-x-datadog-tags="_dd.p.dm=-1,_dd.p.tid=671f3a9100000000",X-TRACE-traceparent="00-671f3a910000000063a887c5a937dbbd-20fbeb28961ee0c3-01",X-TRACE-tracestate="dd=s:1;p:20fbeb28961ee0c3;t.dm:-1;t.tid:671f3a9100000000",X-TRACE-x-datadog-trace-id="7181138888859573181",X-TRACE-x-datadog-parent-id="2376751787917893827"`
decoder := &HLSSpanDecoder{}
c, err := decoder.Decode(m3u8)
assert.NoError(t, err)
assert.NotNil(t, c)
sc, ok := c.(*HLSSpanContext)
assert.True(t, ok)
assert.NotNil(t, sc)
assert.NotNil(t, sc.SpanContext)
assert.Equal(t, uint64(7181138888859573181), sc.SpanContext.TraceID())
assert.Equal(t, uint64(2376751787917893827), sc.SpanContext.SpanID())
}
func TestParseAttributes(t *testing.T) {
t.Parallel()
m3u8 := `#EXT-X-DATERANGE:ID="trace-vds3qcWHqGPD4B6WKOv7IA",CLASS="trace-context",START-DATE="2024-10-28T16:17:37+09:00",X-TRACE-x-datadog-sampling-priority="1",X-TRACE-x-datadog-tags="_dd.p.dm=-1,_dd.p.tid=671f3a9100000000",X-TRACE-traceparent="00-671f3a910000000063a887c5a937dbbd-20fbeb28961ee0c3-01",X-TRACE-tracestate="dd=s:1;p:20fbeb28961ee0c3;t.dm:-1;t.tid:671f3a9100000000",X-TRACE-x-datadog-trace-id="7181138888859573181",X-TRACE-x-datadog-parent-id="2376751787917893827"`
a, err := parseAttributes(m3u8)
assert.NoError(t, err)
assert.NotNil(t, a)
}
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