logger: add ability to fill fileds from context

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

tracer/noop.go

@@ -4,6 +4,7 @@ import (
 	"context"
 
 	"go.unistack.org/micro/v4/options"
+	"go.unistack.org/micro/v4/util/id"
 )
 
 var _ Tracer = (*noopTracer)(nil)
@@ -26,6 +27,8 @@ func (t *noopTracer) Start(ctx context.Context, name string, opts ...options.Opt
 		labels: options.Labels,
 		kind:   options.Kind,
 	}
+	span.spanID, _ = id.New()
+	span.traceID, _ = id.New()
 	if span.ctx == nil {
 		span.ctx = context.Background()
 	}
@@ -63,6 +66,8 @@ type noopSpan struct {
 	logs      []interface{}
 	kind      SpanKind
 	status    SpanStatus
+	traceID   string
+	spanID    string
 }
 
 func (s *noopSpan) Finish(opts ...options.Option) {
@@ -97,6 +102,14 @@ func (s *noopSpan) Kind() SpanKind {
 	return s.kind
 }
 
+func (s *noopSpan) TraceID() string {
+	return s.traceID
+}
+
+func (s *noopSpan) SpanID() string {
+	return s.spanID
+}
+
 func (s *noopSpan) Status() (SpanStatus, string) {
 	return s.status, s.statusMsg
 }

tracer/tracer.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"sort"
 
+	"go.unistack.org/micro/v4/logger"
 	"go.unistack.org/micro/v4/options"
 )
 
@@ -45,6 +46,20 @@ type Span interface {
 	AddLogs(kv ...interface{})
 	// Kind returns span kind
 	Kind() SpanKind
+	// TraceID returns trace id
+	TraceID() string
+	// SpanID returns span id
+	SpanID() string
+}
+
+func init() {
+	logger.DefaultContextAttrFuncs = append(logger.DefaultContextAttrFuncs, func(ctx context.Context) []interface{} {
+		span, ok := SpanFromContext(ctx)
+		if !ok || span == nil {
+			return nil
+		}
+		return []interface{}{"trace", span.TraceID(), "span", span.SpanID()}
+	})
 }
 
 // sort labels alphabeticaly by label name