ReplaceAttrでOpenTelemetryのトレースID/スパンIDを仕込む

code:log_test.go

var (

traceID = trace.TraceID{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'}

spanID = trace.SpanID{'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n'}

)

sc := trace.NewSpanContext(trace.SpanContextConfig{

TraceID: traceID,

SpanID: spanID,

})

tracedCtx := trace.ContextWithSpanContext(ctx, sc)

slog.Info("msg")

code:handler.go

func addSpanContextAttrs(record *slog.Record, sc trace.SpanContext) {

ret := slog.NewRecord(record.Time, record.Level, record.Message, record.PC)

defer func() { *record = ret }()

attrTraceID := slog.String("trace_id", sc.TraceID().String())

attrSpanID := slog.String("span_id", sc.SpanID().String())

for a := range record.Attrs {

if a.Key == "otel" && a.Value.Kind() == slog.KindGroup {

subAttrs := a.Value.Group()

subAttrs = append(subAttrs, attrTraceID, attrSpanID)

ret.AddAttrs(slog.GroupAttrs(a.Key, subAttrs...))

return

}

ret.AddAttrs(a)

}

ret.AddAttrs(slog.GroupAttrs("otel", attrTraceID, attrSpanID))

}