blob: bc7302e3ad39f868498e6cea74b0d6507eee0d5c [file] [log] [blame]
package grpc_opentracing
import (
"strings"
grpc_ctxtags "github.com/grpc-ecosystem/go-grpc-middleware/tags"
opentracing "github.com/opentracing/opentracing-go"
"google.golang.org/grpc/grpclog"
)
const (
TagTraceId = "trace.traceid"
TagSpanId = "trace.spanid"
TagSampled = "trace.sampled"
jaegerNotSampledFlag = "0"
)
// injectOpentracingIdsToTags writes trace data to 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
// Datadog uses keys ending with 'trace-id' and 'parent-id' (for span) by default:
// https://github.com/DataDog/dd-trace-go/blob/v1/ddtrace/tracer/textmap.go#L77
func injectOpentracingIdsToTags(traceHeaderName string, span opentracing.Span, tags grpc_ctxtags.Tags) {
if err := span.Tracer().Inject(span.Context(), opentracing.HTTPHeaders,
&tagsCarrier{Tags: tags, traceHeaderName: traceHeaderName}); err != nil {
grpclog.Infof("grpc_opentracing: failed extracting trace info into ctx %v", err)
}
}
// tagsCarrier is a really hacky way of
type tagsCarrier struct {
grpc_ctxtags.Tags
traceHeaderName string
}
func (t *tagsCarrier) Set(key, val string) {
key = strings.ToLower(key)
if key == t.traceHeaderName {
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")
}
return
}
}
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 strings.HasSuffix(key, "trace-id") {
t.Tags.Set(TagTraceId, val)
}
if strings.HasSuffix(key, "parent-id") {
t.Tags.Set(TagSpanId, val)
}
}