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/
id_extract.go
67 lines (57 loc) · 2.21 KB
/
id_extract.go
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package http_opentracing
import (
"log"
"strings"
http_ctxtags "github.com/improbable-eng/go-httpwares/tags"
opentracing "github.com/opentracing/opentracing-go"
)
const (
TagTraceId = "trace.traceid"
TagSpanId = "trace.spanid"
TagSampled = "trace.sampled"
jaegerNotSampledFlag = "0"
)
// injectOpentracingIdsToTags writes the given context to the ctxtags.
// This is done in an incredibly hacky way, because the public-facing interface of opentracing doesn't give access to
// the TraceId and SpanId of the SpanContext. Only the Tracer's Inject/Extract methods know what these are.
// Most tracers have them encoded as keys with 'traceid' and 'spanid':
// https://github.com/openzipkin/zipkin-go-opentracing/blob/594640b9ef7e5c994e8d9499359d693c032d738c/propagation_ot.go#L29
// https://github.com/opentracing/basictracer-go/blob/1b32af207119a14b1b231d451df3ed04a72efebf/propagation_ot.go#L26
// Jaeger from Uber use one-key schema with next format '{trace-id}:{span-id}:{parent-span-id}:{flags}'
// https://www.jaegertracing.io/docs/client-libraries/#trace-span-identity
func injectOpentracingIdsToTags(span opentracing.Span, tags *http_ctxtags.Tags) {
if err := span.Tracer().Inject(span.Context(), opentracing.HTTPHeaders, &tagsCarrier{tags}); err != nil {
log.Printf("http_opentracing: failed extracting trace info into ctx %v", err)
}
}
// tagsCarrier is a really hacky way of
type tagsCarrier struct {
*http_ctxtags.Tags
}
func (t *tagsCarrier) Set(key, val string) {
key = strings.ToLower(key)
if strings.Contains(key, "traceid") {
t.Tags.Set(TagTraceId, val) // this will most likely be base-16 (hex) encoded
}
if strings.Contains(key, "spanid") && !strings.Contains(strings.ToLower(key), "parent") {
t.Tags.Set(TagSpanId, val) // this will most likely be base-16 (hex) encoded
}
if strings.Contains(key, "sampled") {
switch val {
case "true", "false":
t.Tags.Set(TagSampled, val)
}
}
if key == "uber-trace-id" {
parts := strings.Split(val, ":")
if len(parts) == 4 {
t.Tags.Set(TagTraceId, parts[0])
t.Tags.Set(TagSpanId, parts[1])
if parts[3] != jaegerNotSampledFlag {
t.Tags.Set(TagSampled, "true")
} else {
t.Tags.Set(TagSampled, "false")
}
}
}
}