chore: add support for json codec in jaeger (open-telemetry#28625)

**Description:** Add support for JSON protocol for Jaeger codec. 

**Link to tracking Issue:**
[open-telemetry#6272](open-telemetry#28686)

.chloggen/add-json-jaeger.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: 'enhancement'
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: encoding/jaegerencodingextension
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add support for JSON protocol for jaeger codec
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [6272]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

extension/encoding/jaegerencodingextension/config.go

@@ -10,6 +10,7 @@ type JaegerProtocol string
 
 const (
 	JaegerProtocolProtobuf JaegerProtocol = "protobuf"
+	JaegerProtocolJSON     JaegerProtocol = "json"
 )
 
 type Config struct {
@@ -19,6 +20,7 @@ type Config struct {
 func (c *Config) Validate() error {
 	switch c.Protocol {
 	case JaegerProtocolProtobuf:
+	case JaegerProtocolJSON:
 	default:
 		return fmt.Errorf("invalid protocol %q", c.Protocol)
 	}

extension/encoding/jaegerencodingextension/extension.go

@@ -14,6 +14,7 @@ import (
 )
 
 var _ encoding.TracesUnmarshalerExtension = &jaegerExtension{}
+var _ ptrace.Unmarshaler = &jaegerExtension{}
 
 type jaegerExtension struct {
 	config      *Config
@@ -28,6 +29,8 @@ func (e *jaegerExtension) Start(_ context.Context, _ component.Host) error {
 	switch e.config.Protocol {
 	case JaegerProtocolProtobuf:
 		e.unmarshaler = jaegerProtobufTrace{}
+	case JaegerProtocolJSON:
+		e.unmarshaler = jaegerJSONTrace{}
 	default:
 		return fmt.Errorf("unsupported protocol: %q", e.config.Protocol)
 	}

extension/encoding/jaegerencodingextension/go.mod

@@ -3,6 +3,7 @@ module github.com/open-telemetry/opentelemetry-collector-contrib/extension/encod
 go 1.20
 
 require (
+	github.com/gogo/protobuf v1.3.2
 	github.com/jaegertracing/jaeger v1.52.0
 	github.com/open-telemetry/opentelemetry-collector-contrib/extension/encoding v0.91.0
 	github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/jaeger v0.91.0
@@ -17,7 +18,6 @@ require (
 require (
 	github.com/apache/thrift v0.19.0 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
-	github.com/gogo/protobuf v1.3.2 // indirect
 	github.com/golang/protobuf v1.5.3 // indirect
 	github.com/hashicorp/go-version v1.6.0 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect

extension/encoding/jaegerencodingextension/jaeger.go

@@ -4,6 +4,9 @@
 package jaegerencodingextension // import "github.com/open-telemetry/opentelemetry-collector-contrib/extension/encoding/jaegerencodingextension"
 
 import (
+	"bytes"
+
+	"github.com/gogo/protobuf/jsonpb"
 	jaegerproto "github.com/jaegertracing/jaeger/model"
 	"go.opentelemetry.io/collector/pdata/ptrace"
 
@@ -19,6 +22,22 @@ func (j jaegerProtobufTrace) UnmarshalTraces(buf []byte) (ptrace.Traces, error)
 	if err != nil {
 		return ptrace.NewTraces(), err
 	}
+	return jaegerSpanToTraces(span)
+}
+
+type jaegerJSONTrace struct {
+}
+
+func (j jaegerJSONTrace) UnmarshalTraces(buf []byte) (ptrace.Traces, error) {
+	span := &jaegerproto.Span{}
+	err := jsonpb.Unmarshal(bytes.NewReader(buf), span)
+	if err != nil {
+		return ptrace.NewTraces(), err
+	}
+	return jaegerSpanToTraces(span)
+}
+
+func jaegerSpanToTraces(span *jaegerproto.Span) (ptrace.Traces, error) {
 	batch := jaegerproto.Batch{
 		Spans:   []*jaegerproto.Span{span},
 		Process: span.Process,

extension/encoding/jaegerencodingextension/jaeger_test.go

@@ -0,0 +1,60 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package jaegerencodingextension
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/gogo/protobuf/jsonpb"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"go.opentelemetry.io/collector/pdata/pcommon"
+	"go.opentelemetry.io/collector/pdata/ptrace"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/jaeger"
+)
+
+func TestUnmarshalJaeger(t *testing.T) {
+	td := ptrace.NewTraces()
+	span := td.ResourceSpans().AppendEmpty().ScopeSpans().AppendEmpty().Spans().AppendEmpty()
+	span.SetName("foo")
+	span.SetStartTimestamp(pcommon.Timestamp(10))
+	span.SetEndTimestamp(pcommon.Timestamp(20))
+	span.SetTraceID([16]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16})
+	span.SetSpanID([8]byte{1, 2, 3, 4, 5, 6, 7, 8})
+	batches, err := jaeger.ProtoFromTraces(td)
+	require.NoError(t, err)
+
+	protoBytes, err := batches[0].Spans[0].Marshal()
+	require.NoError(t, err)
+
+	jsonMarshaler := &jsonpb.Marshaler{}
+	jsonBytes := new(bytes.Buffer)
+	require.NoError(t, jsonMarshaler.Marshal(jsonBytes, batches[0].Spans[0]))
+
+	tests := []struct {
+		unmarshaler ptrace.Unmarshaler
+		encoding    string
+		bytes       []byte
+	}{
+		{
+			unmarshaler: jaegerProtobufTrace{},
+			encoding:    "jaeger_proto",
+			bytes:       protoBytes,
+		},
+		{
+			unmarshaler: jaegerJSONTrace{},
+			encoding:    "jaeger_json",
+			bytes:       jsonBytes.Bytes(),
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.encoding, func(t *testing.T) {
+			got, err := test.unmarshaler.UnmarshalTraces(test.bytes)
+			require.NoError(t, err)
+			assert.Equal(t, td, got)
+		})
+	}
+}