Support BYTESLICE attributes across trace and exporter paths (#8153)

Fixes https://github.com/open-telemetry/opentelemetry-go/issues/8164

Supersedes #8042 which does not address the `trace` or `zipkin`
packages, and has unrelated support changes.

Add end-to-end handling for `attribute.BYTESLICE` in the remaining trace
and exporter paths that still dropped, invalidated, or stringified byte
slice attributes.

This change:

- preserves byte slice attributes in `trace/auto`
- encodes byte slice attributes as OTLP `AnyValue_BytesValue` in trace,
log, and metric transforms
- serializes Zipkin byte slice attributes as JSON arrays of byte values
- adds regression tests for each updated path

## Problem

`attribute.BYTESLICE` is public, but several downstream conversions
still did not handle it correctly:

- `trace/auto` dropped byte slice attributes during conversion
- OTLP trace, log, and metric transforms fell through to their invalid
default handling
- Zipkin fell back to `Value.Emit()`, which produced a base64 string
rather than an explicit byte-array representation

That made `BYTESLICE` unusable or inconsistent depending on the export
path.

## Changes

### Trace

- Handle `attribute.BYTESLICE` in `trace/auto` by converting it to an
internal telemetry bytes value.
- Add a regression test covering byte slice conversion.

### OTLP

- Handle `attribute.BYTESLICE` in:
  - trace attribute transform
  - log gRPC attribute transform
  - log HTTP attribute transform
  - metric HTTP attribute transform
  - metric gRPC attribute transform
- Update the shared log and metric transform templates so generated
outputs stay aligned.
- Add regression tests for the trace transform, both log transform
outputs, and both metric transform outputs.

### Zipkin

- Handle `attribute.BYTESLICE` explicitly in Zipkin tag serialization.
- Serialize byte slices as JSON arrays of byte values instead of base64
text.
- Add a regression test for Zipkin byte slice serialization.

---------

Co-authored-by: Robert Pająk <pellared@hotmail.com>

CHANGELOG.md

@@ -25,6 +25,11 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 ### Fixed
 
 - Fix gzipped request body replay on redirect in `go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp`. (#8152)
+- Support `BYTESLICE` attributes in `go.opentelemetry.io/otel/trace`. (#8153)
+- Support `BYTESLICE` attributes in `go.opentelemetry.io/otel/exporters/otlp/otlptrace`. (#8153)
+- Support `BYTESLICE` attributes in `go.opentelemetry.io/otel/exporters/otlp/otlplog`. (#8153)
+- Support `BYTESLICE` attributes in `go.opentelemetry.io/otel/exporters/otlp/otlpmetric`. (#8153)
+- Support `BYTESLICE` attributes in `go.opentelemetry.io/otel/exporters/zipkin`. (#8153)
 
 <!-- Released section -->
 <!-- Don't change this section unless doing release -->

exporters/otlp/otlplog/otlploggrpc/internal/transform/attr_test.go

@@ -25,6 +25,7 @@ var (
 	attrFloat64      = attribute.Float64("float64", 1)
 	attrFloat64Slice = attribute.Float64Slice("float64 slice", []float64{-1, 1})
 	attrString       = attribute.String("string", "o")
+	attrBytes        = attribute.ByteSlice("bytes", []byte("otlp"))
 	attrStringSlice  = attribute.StringSlice("string slice", []string{"o", "n"})
 	attrEmpty        = attribute.KeyValue{
 		Key:   attribute.Key("empty"),
@@ -53,6 +54,7 @@ var (
 		},
 	}}
 	valStrO     = &cpb.AnyValue{Value: &cpb.AnyValue_StringValue{StringValue: "o"}}
+	valAttrBytes = &cpb.AnyValue{Value: &cpb.AnyValue_BytesValue{BytesValue: []byte("otlp")}}
 	valStrN     = &cpb.AnyValue{Value: &cpb.AnyValue_StringValue{StringValue: "n"}}
 	valStrSlice = &cpb.AnyValue{Value: &cpb.AnyValue_ArrayValue{
 		ArrayValue: &cpb.ArrayValue{
@@ -69,6 +71,7 @@ var (
 	kvFloat64      = &cpb.KeyValue{Key: "float64", Value: valDblOne}
 	kvFloat64Slice = &cpb.KeyValue{Key: "float64 slice", Value: valDblSlice}
 	kvString       = &cpb.KeyValue{Key: "string", Value: valStrO}
+	kvAttrBytes    = &cpb.KeyValue{Key: "bytes", Value: valAttrBytes}
 	kvStringSlice  = &cpb.KeyValue{Key: "string slice", Value: valStrSlice}
 	kvEmpty        = &cpb.KeyValue{Key: "empty", Value: &cpb.AnyValue{}}
 )
@@ -133,6 +136,11 @@ func TestAttrTransforms(t *testing.T) {
 			[]attribute.KeyValue{attrString},
 			[]*cpb.KeyValue{kvString},
 		},
+		{
+			"bytes",
+			[]attribute.KeyValue{attrBytes},
+			[]*cpb.KeyValue{kvAttrBytes},
+		},
 		{
 			"string slice",
 			[]attribute.KeyValue{attrStringSlice},
@@ -150,6 +158,7 @@ func TestAttrTransforms(t *testing.T) {
 				attrFloat64,
 				attrFloat64Slice,
 				attrString,
+				attrBytes,
 				attrStringSlice,
 				attrEmpty,
 			},
@@ -163,6 +172,7 @@ func TestAttrTransforms(t *testing.T) {
 				kvFloat64,
 				kvFloat64Slice,
 				kvString,
+				kvAttrBytes,
 				kvStringSlice,
 				kvEmpty,
 			},

exporters/otlp/otlplog/otlploggrpc/internal/transform/log.go

@@ -195,6 +195,10 @@ func AttrValue(v attribute.Value) *cpb.AnyValue {
 		av.Value = &cpb.AnyValue_StringValue{
 			StringValue: v.AsString(),
 		}
+	case attribute.BYTESLICE:
+		av.Value = &cpb.AnyValue_BytesValue{
+			BytesValue: v.AsByteSlice(),
+		}
 	case attribute.STRINGSLICE:
 		av.Value = &cpb.AnyValue_ArrayValue{
 			ArrayValue: &cpb.ArrayValue{

exporters/otlp/otlplog/otlploghttp/internal/transform/attr_test.go

@@ -25,6 +25,7 @@ var (
 	attrFloat64      = attribute.Float64("float64", 1)
 	attrFloat64Slice = attribute.Float64Slice("float64 slice", []float64{-1, 1})
 	attrString       = attribute.String("string", "o")
+	attrBytes        = attribute.ByteSlice("bytes", []byte("otlp"))
 	attrStringSlice  = attribute.StringSlice("string slice", []string{"o", "n"})
 	attrEmpty        = attribute.KeyValue{
 		Key:   attribute.Key("empty"),
@@ -53,6 +54,7 @@ var (
 		},
 	}}
 	valStrO     = &cpb.AnyValue{Value: &cpb.AnyValue_StringValue{StringValue: "o"}}
+	valAttrBytes = &cpb.AnyValue{Value: &cpb.AnyValue_BytesValue{BytesValue: []byte("otlp")}}
 	valStrN     = &cpb.AnyValue{Value: &cpb.AnyValue_StringValue{StringValue: "n"}}
 	valStrSlice = &cpb.AnyValue{Value: &cpb.AnyValue_ArrayValue{
 		ArrayValue: &cpb.ArrayValue{
@@ -69,6 +71,7 @@ var (
 	kvFloat64      = &cpb.KeyValue{Key: "float64", Value: valDblOne}
 	kvFloat64Slice = &cpb.KeyValue{Key: "float64 slice", Value: valDblSlice}
 	kvString       = &cpb.KeyValue{Key: "string", Value: valStrO}
+	kvAttrBytes    = &cpb.KeyValue{Key: "bytes", Value: valAttrBytes}
 	kvStringSlice  = &cpb.KeyValue{Key: "string slice", Value: valStrSlice}
 	kvEmpty        = &cpb.KeyValue{Key: "empty", Value: &cpb.AnyValue{}}
 )
@@ -133,6 +136,11 @@ func TestAttrTransforms(t *testing.T) {
 			[]attribute.KeyValue{attrString},
 			[]*cpb.KeyValue{kvString},
 		},
+		{
+			"bytes",
+			[]attribute.KeyValue{attrBytes},
+			[]*cpb.KeyValue{kvAttrBytes},
+		},
 		{
 			"string slice",
 			[]attribute.KeyValue{attrStringSlice},
@@ -150,6 +158,7 @@ func TestAttrTransforms(t *testing.T) {
 				attrFloat64,
 				attrFloat64Slice,
 				attrString,
+				attrBytes,
 				attrStringSlice,
 				attrEmpty,
 			},
@@ -163,6 +172,7 @@ func TestAttrTransforms(t *testing.T) {
 				kvFloat64,
 				kvFloat64Slice,
 				kvString,
+				kvAttrBytes,
 				kvStringSlice,
 				kvEmpty,
 			},

exporters/otlp/otlplog/otlploghttp/internal/transform/log.go

@@ -195,6 +195,10 @@ func AttrValue(v attribute.Value) *cpb.AnyValue {
 		av.Value = &cpb.AnyValue_StringValue{
 			StringValue: v.AsString(),
 		}
+	case attribute.BYTESLICE:
+		av.Value = &cpb.AnyValue_BytesValue{
+			BytesValue: v.AsByteSlice(),
+		}
 	case attribute.STRINGSLICE:
 		av.Value = &cpb.AnyValue_ArrayValue{
 			ArrayValue: &cpb.ArrayValue{

exporters/otlp/otlpmetric/otlpmetricgrpc/internal/transform/attribute.go

@@ -81,6 +81,10 @@ func Value(v attribute.Value) *cpb.AnyValue {
 		av.Value = &cpb.AnyValue_StringValue{
 			StringValue: v.AsString(),
 		}
+	case attribute.BYTESLICE:
+		av.Value = &cpb.AnyValue_BytesValue{
+			BytesValue: v.AsByteSlice(),
+		}
 	case attribute.STRINGSLICE:
 		av.Value = &cpb.AnyValue_ArrayValue{
 			ArrayValue: &cpb.ArrayValue{

exporters/otlp/otlpmetric/otlpmetricgrpc/internal/transform/attribute_test.go

@@ -25,6 +25,7 @@ var (
 	attrFloat64      = attribute.Float64("float64", 1)
 	attrFloat64Slice = attribute.Float64Slice("float64 slice", []float64{-1, 1})
 	attrString       = attribute.String("string", "o")
+	attrBytes        = attribute.ByteSlice("bytes", []byte("otlp"))
 	attrStringSlice  = attribute.StringSlice("string slice", []string{"o", "n"})
 	attrEmpty        = attribute.KeyValue{
 		Key:   attribute.Key("empty"),
@@ -53,6 +54,7 @@ var (
 		},
 	}}
 	valStrO     = &cpb.AnyValue{Value: &cpb.AnyValue_StringValue{StringValue: "o"}}
+	valBytes    = &cpb.AnyValue{Value: &cpb.AnyValue_BytesValue{BytesValue: []byte("otlp")}}
 	valStrN     = &cpb.AnyValue{Value: &cpb.AnyValue_StringValue{StringValue: "n"}}
 	valStrSlice = &cpb.AnyValue{Value: &cpb.AnyValue_ArrayValue{
 		ArrayValue: &cpb.ArrayValue{
@@ -69,6 +71,7 @@ var (
 	kvFloat64      = &cpb.KeyValue{Key: "float64", Value: valDblOne}
 	kvFloat64Slice = &cpb.KeyValue{Key: "float64 slice", Value: valDblSlice}
 	kvString       = &cpb.KeyValue{Key: "string", Value: valStrO}
+	kvBytes        = &cpb.KeyValue{Key: "bytes", Value: valBytes}
 	kvStringSlice  = &cpb.KeyValue{Key: "string slice", Value: valStrSlice}
 	kvEmpty        = &cpb.KeyValue{Key: "empty", Value: &cpb.AnyValue{}}
 )
@@ -133,6 +136,11 @@ func TestAttributeTransforms(t *testing.T) {
 			[]attribute.KeyValue{attrString},
 			[]*cpb.KeyValue{kvString},
 		},
+		{
+			"bytes",
+			[]attribute.KeyValue{attrBytes},
+			[]*cpb.KeyValue{kvBytes},
+		},
 		{
 			"string slice",
 			[]attribute.KeyValue{attrStringSlice},
@@ -150,6 +158,7 @@ func TestAttributeTransforms(t *testing.T) {
 				attrFloat64,
 				attrFloat64Slice,
 				attrString,
+				attrBytes,
 				attrStringSlice,
 				attrEmpty,
 			},
@@ -163,6 +172,7 @@ func TestAttributeTransforms(t *testing.T) {
 				kvFloat64,
 				kvFloat64Slice,
 				kvString,
+				kvBytes,
 				kvStringSlice,
 				kvEmpty,
 			},

exporters/otlp/otlpmetric/otlpmetrichttp/internal/transform/attribute.go

@@ -81,6 +81,10 @@ func Value(v attribute.Value) *cpb.AnyValue {
 		av.Value = &cpb.AnyValue_StringValue{
 			StringValue: v.AsString(),
 		}
+	case attribute.BYTESLICE:
+		av.Value = &cpb.AnyValue_BytesValue{
+			BytesValue: v.AsByteSlice(),
+		}
 	case attribute.STRINGSLICE:
 		av.Value = &cpb.AnyValue_ArrayValue{
 			ArrayValue: &cpb.ArrayValue{

exporters/otlp/otlpmetric/otlpmetrichttp/internal/transform/attribute_test.go

@@ -25,6 +25,7 @@ var (
 	attrFloat64      = attribute.Float64("float64", 1)
 	attrFloat64Slice = attribute.Float64Slice("float64 slice", []float64{-1, 1})
 	attrString       = attribute.String("string", "o")
+	attrBytes        = attribute.ByteSlice("bytes", []byte("otlp"))
 	attrStringSlice  = attribute.StringSlice("string slice", []string{"o", "n"})
 	attrEmpty        = attribute.KeyValue{
 		Key:   attribute.Key("empty"),
@@ -53,6 +54,7 @@ var (
 		},
 	}}
 	valStrO     = &cpb.AnyValue{Value: &cpb.AnyValue_StringValue{StringValue: "o"}}
+	valBytes    = &cpb.AnyValue{Value: &cpb.AnyValue_BytesValue{BytesValue: []byte("otlp")}}
 	valStrN     = &cpb.AnyValue{Value: &cpb.AnyValue_StringValue{StringValue: "n"}}
 	valStrSlice = &cpb.AnyValue{Value: &cpb.AnyValue_ArrayValue{
 		ArrayValue: &cpb.ArrayValue{
@@ -69,6 +71,7 @@ var (
 	kvFloat64      = &cpb.KeyValue{Key: "float64", Value: valDblOne}
 	kvFloat64Slice = &cpb.KeyValue{Key: "float64 slice", Value: valDblSlice}
 	kvString       = &cpb.KeyValue{Key: "string", Value: valStrO}
+	kvBytes        = &cpb.KeyValue{Key: "bytes", Value: valBytes}
 	kvStringSlice  = &cpb.KeyValue{Key: "string slice", Value: valStrSlice}
 	kvEmpty        = &cpb.KeyValue{Key: "empty", Value: &cpb.AnyValue{}}
 )
@@ -133,6 +136,11 @@ func TestAttributeTransforms(t *testing.T) {
 			[]attribute.KeyValue{attrString},
 			[]*cpb.KeyValue{kvString},
 		},
+		{
+			"bytes",
+			[]attribute.KeyValue{attrBytes},
+			[]*cpb.KeyValue{kvBytes},
+		},
 		{
 			"string slice",
 			[]attribute.KeyValue{attrStringSlice},
@@ -150,6 +158,7 @@ func TestAttributeTransforms(t *testing.T) {
 				attrFloat64,
 				attrFloat64Slice,
 				attrString,
+				attrBytes,
 				attrStringSlice,
 				attrEmpty,
 			},
@@ -163,6 +172,7 @@ func TestAttributeTransforms(t *testing.T) {
 				kvFloat64,
 				kvFloat64Slice,
 				kvString,
+				kvBytes,
 				kvStringSlice,
 				kvEmpty,
 			},

exporters/otlp/otlptrace/internal/tracetransform/attribute.go

@@ -87,6 +87,10 @@ func Value(v attribute.Value) *commonpb.AnyValue {
 		av.Value = &commonpb.AnyValue_StringValue{
 			StringValue: v.AsString(),
 		}
+	case attribute.BYTESLICE:
+		av.Value = &commonpb.AnyValue_BytesValue{
+			BytesValue: v.AsByteSlice(),
+		}
 	case attribute.STRINGSLICE:
 		av.Value = &commonpb.AnyValue_ArrayValue{
 			ArrayValue: &commonpb.ArrayValue{

exporters/otlp/otlptrace/internal/tracetransform/attribute_test.go

@@ -26,6 +26,7 @@ func TestAttributes(t *testing.T) {
 				attribute.Int64("int64 to int64", 1234567),
 				attribute.Float64("float64 to double", 1.61),
 				attribute.String("string to string", "string"),
+				attribute.ByteSlice("bytes to bytes", []byte("bytes")),
 				attribute.Bool("bool to bool", true),
 				{Key: "empty to empty"},
 			},
@@ -62,6 +63,14 @@ func TestAttributes(t *testing.T) {
 						},
 					},
 				},
+				{
+					Key: "bytes to bytes",
+					Value: &commonpb.AnyValue{
+						Value: &commonpb.AnyValue_BytesValue{
+							BytesValue: []byte("bytes"),
+						},
+					},
+				},
 				{
 					Key: "bool to bool",
 					Value: &commonpb.AnyValue{

exporters/zipkin/model.go

@@ -174,6 +174,14 @@ func attributeToStringPair(kv attribute.KeyValue) (string, string) {
 	case attribute.STRINGSLICE:
 		data, _ := json.Marshal(kv.Value.AsStringSlice())
 		return string(kv.Key), string(data)
+	case attribute.BYTESLICE:
+		raw := kv.Value.AsByteSlice()
+		data := make([]int, len(raw))
+		for i, b := range raw {
+			data[i] = int(b)
+		}
+		encoded, _ := json.Marshal(data)
+		return string(kv.Key), string(encoded)
 	default:
 		return string(kv.Key), kv.Value.Emit()
 	}

exporters/zipkin/model_test.go

@@ -982,6 +982,15 @@ func TestModelConversion(t *testing.T) {
 	require.Equal(t, expectedOutputBatch, gottenOutputBatch)
 }
 
+func TestAttributeToStringPairByteSlice(t *testing.T) {
+	t.Parallel()
+
+	k, v := attributeToStringPair(attribute.ByteSlice("bytes", []byte{1, 2, 3}))
+
+	assert.Equal(t, "bytes", k)
+	assert.Equal(t, "[1,2,3]", v)
+}
+
 func zkmodelIDPtr(n uint64) *zkmodel.ID {
 	id := zkmodel.ID(n)
 	return &id

internal/shared/otlp/otlplog/transform/attr_test.go.tmpl

@@ -25,6 +25,7 @@ var (
 	attrFloat64      = attribute.Float64("float64", 1)
 	attrFloat64Slice = attribute.Float64Slice("float64 slice", []float64{-1, 1})
 	attrString       = attribute.String("string", "o")
+	attrBytes        = attribute.ByteSlice("bytes", []byte("otlp"))
 	attrStringSlice  = attribute.StringSlice("string slice", []string{"o", "n"})
 	attrEmpty        = attribute.KeyValue{
 		Key:   attribute.Key("empty"),
@@ -53,6 +54,7 @@ var (
 		},
 	}}
 	valStrO     = &cpb.AnyValue{Value: &cpb.AnyValue_StringValue{StringValue: "o"}}
+	valAttrBytes = &cpb.AnyValue{Value: &cpb.AnyValue_BytesValue{BytesValue: []byte("otlp")}}
 	valStrN     = &cpb.AnyValue{Value: &cpb.AnyValue_StringValue{StringValue: "n"}}
 	valStrSlice = &cpb.AnyValue{Value: &cpb.AnyValue_ArrayValue{
 		ArrayValue: &cpb.ArrayValue{
@@ -69,6 +71,7 @@ var (
 	kvFloat64      = &cpb.KeyValue{Key: "float64", Value: valDblOne}
 	kvFloat64Slice = &cpb.KeyValue{Key: "float64 slice", Value: valDblSlice}
 	kvString       = &cpb.KeyValue{Key: "string", Value: valStrO}
+	kvAttrBytes    = &cpb.KeyValue{Key: "bytes", Value: valAttrBytes}
 	kvStringSlice  = &cpb.KeyValue{Key: "string slice", Value: valStrSlice}
 	kvEmpty        = &cpb.KeyValue{Key: "empty", Value: &cpb.AnyValue{}}
 )
@@ -133,6 +136,11 @@ func TestAttrTransforms(t *testing.T) {
 			[]attribute.KeyValue{attrString},
 			[]*cpb.KeyValue{kvString},
 		},
+		{
+			"bytes",
+			[]attribute.KeyValue{attrBytes},
+			[]*cpb.KeyValue{kvAttrBytes},
+		},
 		{
 			"string slice",
 			[]attribute.KeyValue{attrStringSlice},
@@ -150,6 +158,7 @@ func TestAttrTransforms(t *testing.T) {
 				attrFloat64,
 				attrFloat64Slice,
 				attrString,
+				attrBytes,
 				attrStringSlice,
 				attrEmpty,
 			},
@@ -163,6 +172,7 @@ func TestAttrTransforms(t *testing.T) {
 				kvFloat64,
 				kvFloat64Slice,
 				kvString,
+				kvAttrBytes,
 				kvStringSlice,
 				kvEmpty,
 			},

internal/shared/otlp/otlplog/transform/log.go.tmpl

@@ -195,6 +195,10 @@ func AttrValue(v attribute.Value) *cpb.AnyValue {
 		av.Value = &cpb.AnyValue_StringValue{
 			StringValue: v.AsString(),
 		}
+	case attribute.BYTESLICE:
+		av.Value = &cpb.AnyValue_BytesValue{
+			BytesValue: v.AsByteSlice(),
+		}
 	case attribute.STRINGSLICE:
 		av.Value = &cpb.AnyValue_ArrayValue{
 			ArrayValue: &cpb.ArrayValue{

internal/shared/otlp/otlpmetric/transform/attribute.go.tmpl

@@ -81,6 +81,10 @@ func Value(v attribute.Value) *cpb.AnyValue {
 		av.Value = &cpb.AnyValue_StringValue{
 			StringValue: v.AsString(),
 		}
+	case attribute.BYTESLICE:
+		av.Value = &cpb.AnyValue_BytesValue{
+			BytesValue: v.AsByteSlice(),
+		}
 	case attribute.STRINGSLICE:
 		av.Value = &cpb.AnyValue_ArrayValue{
 			ArrayValue: &cpb.ArrayValue{

internal/shared/otlp/otlpmetric/transform/attribute_test.go.tmpl

@@ -25,6 +25,7 @@ var (
 	attrFloat64      = attribute.Float64("float64", 1)
 	attrFloat64Slice = attribute.Float64Slice("float64 slice", []float64{-1, 1})
 	attrString       = attribute.String("string", "o")
+	attrBytes        = attribute.ByteSlice("bytes", []byte("otlp"))
 	attrStringSlice  = attribute.StringSlice("string slice", []string{"o", "n"})
 	attrEmpty        = attribute.KeyValue{
 		Key:   attribute.Key("empty"),
@@ -53,6 +54,7 @@ var (
 		},
 	}}
 	valStrO     = &cpb.AnyValue{Value: &cpb.AnyValue_StringValue{StringValue: "o"}}
+	valBytes    = &cpb.AnyValue{Value: &cpb.AnyValue_BytesValue{BytesValue: []byte("otlp")}}
 	valStrN     = &cpb.AnyValue{Value: &cpb.AnyValue_StringValue{StringValue: "n"}}
 	valStrSlice = &cpb.AnyValue{Value: &cpb.AnyValue_ArrayValue{
 		ArrayValue: &cpb.ArrayValue{
@@ -69,6 +71,7 @@ var (
 	kvFloat64      = &cpb.KeyValue{Key: "float64", Value: valDblOne}
 	kvFloat64Slice = &cpb.KeyValue{Key: "float64 slice", Value: valDblSlice}
 	kvString       = &cpb.KeyValue{Key: "string", Value: valStrO}
+	kvBytes        = &cpb.KeyValue{Key: "bytes", Value: valBytes}
 	kvStringSlice  = &cpb.KeyValue{Key: "string slice", Value: valStrSlice}
 	kvEmpty        = &cpb.KeyValue{Key: "empty", Value: &cpb.AnyValue{}}
 )
@@ -133,6 +136,11 @@ func TestAttributeTransforms(t *testing.T) {
 			[]attribute.KeyValue{attrString},
 			[]*cpb.KeyValue{kvString},
 		},
+		{
+			"bytes",
+			[]attribute.KeyValue{attrBytes},
+			[]*cpb.KeyValue{kvBytes},
+		},
 		{
 			"string slice",
 			[]attribute.KeyValue{attrStringSlice},
@@ -150,6 +158,7 @@ func TestAttributeTransforms(t *testing.T) {
 				attrFloat64,
 				attrFloat64Slice,
 				attrString,
+				attrBytes,
 				attrStringSlice,
 				attrEmpty,
 			},
@@ -163,6 +172,7 @@ func TestAttributeTransforms(t *testing.T) {
 				kvFloat64,
 				kvFloat64Slice,
 				kvString,
+				kvBytes,
 				kvStringSlice,
 				kvEmpty,
 			},

trace/auto.go

@@ -314,6 +314,8 @@ func convAttrValue(value attribute.Value) telemetry.Value {
 	case attribute.STRING:
 		v := truncate(maxSpan.AttrValueLen, value.AsString())
 		return telemetry.StringValue(v)
+	case attribute.BYTESLICE:
+		return telemetry.BytesValue(value.AsByteSlice())
 	case attribute.BOOLSLICE:
 		slice := value.AsBoolSlice()
 		out := make([]telemetry.Value, 0, len(slice))

trace/auto_test.go

@@ -164,6 +164,15 @@ func TestSpanKindTransform(t *testing.T) {
 	}
 }
 
+func TestConvAttrValueBytes(t *testing.T) {
+	t.Parallel()
+
+	val := convAttrValue(attribute.ByteSliceValue([]byte("bytes")))
+
+	assert.Equal(t, telemetry.ValueKindBytes, val.Kind())
+	assert.Equal(t, []byte("bytes"), val.AsBytes())
+}
+
 func TestTracerStartPropagatesOrigCtx(t *testing.T) {
 	t.Parallel()