[receiver/datadog] Support Span Links

.chloggen/datadog-receiver-support-span-links.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: datadogreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Support for span links in Datadog receiver
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [35963]
+
+# (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: [user]

pkg/translator/zipkin/zipkinv2/to_translator.go

@@ -128,7 +128,7 @@ func zSpanToInternal(zspan *zipkinmodel.SpanModel, tags map[string]string, dest
 	dest.SetKind(zipkinKindToSpanKind(zspan.Kind, tags))
 
 	populateSpanStatus(tags, dest.Status())
-	if err := zTagsToSpanLinks(tags, dest.Links()); err != nil {
+	if err := TagsToSpanLinks(tags, dest.Links()); err != nil {
 		return err
 	}
 
@@ -183,7 +183,8 @@ func zipkinKindToSpanKind(kind zipkinmodel.Kind, tags map[string]string) ptrace.
 	}
 }
 
-func zTagsToSpanLinks(tags map[string]string, dest ptrace.SpanLinkSlice) error {
+// TagsToSpanLinks translates span tags into ptrace.SpanLinkSlice.
+func TagsToSpanLinks(tags map[string]string, dest ptrace.SpanLinkSlice) error {
 	for i := 0; i < 128; i++ {
 		key := fmt.Sprintf("otlp.link.%d", i)
 		val, ok := tags[key]

pkg/translator/zipkin/zipkinv2/to_translator_test.go

@@ -4,11 +4,14 @@
 package zipkinv2
 
 import (
+	"encoding/hex"
+	"strconv"
 	"testing"
 	"time"
 
 	zipkinmodel "github.com/openzipkin/zipkin-go/model"
 	"github.com/stretchr/testify/assert"
+	"go.opentelemetry.io/collector/pdata/pcommon"
 	"go.opentelemetry.io/collector/pdata/ptrace"
 	conventions "go.opentelemetry.io/collector/semconv/v1.6.1"
 
@@ -262,3 +265,162 @@ func TestV2SpanWithoutTimestampGetsTag(t *testing.T) {
 	assert.True(t, mapContainedKey)
 	assert.True(t, wasAbsent.Bool())
 }
+
+func TestTagsToSpanLinks(t *testing.T) {
+	tests := []struct {
+		name          string
+		tags          map[string]string
+		expectedLinks []ptrace.SpanLink
+		expectedError bool
+	}{
+		{
+			name: "Single valid link",
+			tags: map[string]string{
+				"otlp.link.0": "0102030405060708090a0b0c0d0e0f10|0102030405060708|state|{\"attr1\":\"value1\",\"attr2\":123}|0",
+			},
+			expectedLinks: []ptrace.SpanLink{
+				func() ptrace.SpanLink {
+					link := ptrace.NewSpanLink()
+					traceID, _ := hex.DecodeString("0102030405060708090a0b0c0d0e0f10")
+					link.SetTraceID(pcommon.TraceID(traceID))
+					spanID, _ := hex.DecodeString("0102030405060708")
+					link.SetSpanID(pcommon.SpanID(spanID))
+					link.TraceState().FromRaw("state")
+					attrs := link.Attributes()
+					attrs.PutStr("attr1", "value1")
+					attrs.PutInt("attr2", 123)
+					link.SetDroppedAttributesCount(0)
+					return link
+				}(),
+			},
+			expectedError: false,
+		},
+		{
+			name: "Multiple valid links",
+			tags: map[string]string{
+				"otlp.link.0": "0102030405060708090a0b0c0d0e0f10|0102030405060708|state1|{\"attr1\":\"value1\"}|0",
+				"otlp.link.1": "1112131415161718191a1b1c1d1e1f20|1112131415161718|state2|{\"attr2\":456}|1",
+			},
+			expectedLinks: []ptrace.SpanLink{
+				func() ptrace.SpanLink {
+					link := ptrace.NewSpanLink()
+					traceID, _ := hex.DecodeString("0102030405060708090a0b0c0d0e0f10")
+					link.SetTraceID(pcommon.TraceID(traceID))
+					spanID, _ := hex.DecodeString("0102030405060708")
+					link.SetSpanID(pcommon.SpanID(spanID))
+					link.TraceState().FromRaw("state1")
+					attrs := link.Attributes()
+					attrs.PutStr("attr1", "value1")
+					link.SetDroppedAttributesCount(0)
+					return link
+				}(),
+				func() ptrace.SpanLink {
+					link := ptrace.NewSpanLink()
+					traceID, _ := hex.DecodeString("1112131415161718191a1b1c1d1e1f20")
+					link.SetTraceID(pcommon.TraceID(traceID))
+					spanID, _ := hex.DecodeString("1112131415161718")
+					link.SetSpanID(pcommon.SpanID(spanID))
+					link.TraceState().FromRaw("state2")
+					attrs := link.Attributes()
+					attrs.PutInt("attr2", 456)
+					link.SetDroppedAttributesCount(1)
+					return link
+				}(),
+			},
+			expectedError: false,
+		},
+		{
+			name: "Invalid format (too few parts)",
+			tags: map[string]string{
+				"otlp.link.0": "invalid|value",
+			},
+			expectedLinks: []ptrace.SpanLink{},
+			expectedError: false,
+		},
+		{
+			name: "Invalid hex in trace ID",
+			tags: map[string]string{
+				"otlp.link.0": "nothex|0102030405060708|state|{\"attr1\":\"value1\"}|0",
+			},
+			expectedLinks: nil,
+			expectedError: true,
+		},
+		{
+			name: "Invalid dropped attributes count",
+			tags: map[string]string{
+				"otlp.link.0": "0102030405060708090a0b0c0d0e0f10|0102030405060708|state|{\"attr1\":\"value1\"}|notanumber",
+			},
+			expectedLinks: nil,
+			expectedError: true,
+		},
+		{
+			name: "Attributes with pipe character",
+			tags: map[string]string{
+				"otlp.link.0": "0102030405060708090a0b0c0d0e0f10|0102030405060708|state|{\"attr1\":\"value1|with|pipes\"}|0",
+			},
+			expectedLinks: []ptrace.SpanLink{
+				func() ptrace.SpanLink {
+					link := ptrace.NewSpanLink()
+					traceID, _ := hex.DecodeString("0102030405060708090a0b0c0d0e0f10")
+					link.SetTraceID(pcommon.TraceID(traceID))
+					spanID, _ := hex.DecodeString("0102030405060708")
+					link.SetSpanID(pcommon.SpanID(spanID))
+					link.TraceState().FromRaw("state")
+					attrs := link.Attributes()
+					attrs.PutStr("attr1", "value1|with|pipes")
+					link.SetDroppedAttributesCount(0)
+					return link
+				}(),
+			},
+			expectedError: false,
+		},
+		{
+			name:          "No links in tags",
+			tags:          map[string]string{},
+			expectedLinks: []ptrace.SpanLink{},
+			expectedError: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			dest := ptrace.NewSpanLinkSlice()
+			err := TagsToSpanLinks(tt.tags, dest)
+			if tt.expectedError {
+				assert.Error(t, err)
+				return
+			}
+			assert.NoError(t, err)
+			assert.Equal(t, len(tt.expectedLinks), dest.Len())
+
+			for i, expected := range tt.expectedLinks {
+				link := dest.At(i)
+
+				assert.Equal(t, expected.TraceID(), link.TraceID(), "TraceID mismatch")
+				assert.Equal(t, expected.SpanID(), link.SpanID(), "SpanID mismatch")
+				assert.Equal(t, expected.TraceState().AsRaw(), link.TraceState().AsRaw())
+
+				assert.Equal(t, expected.DroppedAttributesCount(), link.DroppedAttributesCount())
+
+				// Verify attributes
+				expectedAttrs := expected.Attributes()
+				actualAttrs := link.Attributes()
+				assert.Equal(t, expectedAttrs.Len(), actualAttrs.Len(), "Attributes length mismatch")
+
+				expectedAttrs.Range(func(k string, v pcommon.Value) bool {
+					actualVal, ok := actualAttrs.Get(k)
+					assert.True(t, ok, "Attribute %s not found in link", k)
+					assert.Equal(t, v, actualVal, "Attribute %s value mismatch", k)
+					return true
+				})
+			}
+
+			// Verify that link tags are removed
+			for i := 0; i < 128; i++ {
+				key := "otlp.link." + strconv.Itoa(i)
+				_, ok := tt.tags[key]
+				assert.False(t, ok, "Expected tag %s to be deleted", key)
+			}
+		})
+	}
+}

receiver/datadogreceiver/README.md

@@ -58,6 +58,11 @@ https://github.com/open-telemetry/opentelemetry-collector/tree/main/config/confi
 
 - `dd.span.Resource`: The datadog resource name (as distinct from the span name)
 
+### Optional Attributes
+- `otlp.link.%d`: This receiver supports `otlp.link.%d` attributes, which are used to create Span Links.
+  The `%d` is a placeholder for the link index. The value of the attribute is a span context serialized as a string separated by `|`, in the format of `trace_id|span_id|tracestate|json_attributes|dropped_attributes_count`.
+  Examples can be found [here](../../pkg/translator/zipkin/zipkinv2/to_translator_test.go).
+
 ### Datadog's API support
 
 **Traces**

receiver/datadogreceiver/go.mod

@@ -12,6 +12,7 @@ require (
 	github.com/open-telemetry/opentelemetry-collector-contrib/internal/coreinternal v0.112.0
 	github.com/open-telemetry/opentelemetry-collector-contrib/internal/exp/metrics v0.112.0
 	github.com/open-telemetry/opentelemetry-collector-contrib/internal/sharedcomponent v0.112.0
+	github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/zipkin v0.112.0
 	github.com/stretchr/testify v1.9.0
 	github.com/tinylib/msgp v1.2.2
 	github.com/vmihailenco/msgpack/v5 v5.4.1
@@ -42,7 +43,7 @@ require (
 	github.com/Microsoft/go-winio v0.6.1 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/cihub/seelog v0.0.0-20170130134532-f561c5e57575 // indirect
-	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/felixge/httpsnoop v1.0.4 // indirect
 	github.com/fsnotify/fsnotify v1.7.0 // indirect
@@ -66,11 +67,12 @@ require (
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
 	github.com/open-telemetry/opentelemetry-collector-contrib/pkg/pdatautil v0.112.0 // indirect
+	github.com/openzipkin/zipkin-go v0.4.3 // indirect
 	github.com/outcaste-io/ristretto v0.2.1 // indirect
 	github.com/philhofer/fwd v1.1.3-0.20240916144458-20a13a1f6b7c // indirect
 	github.com/pierrec/lz4/v4 v4.1.21 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
-	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/power-devops/perfstat v0.0.0-20220216144756-c35f1ee13d7c // indirect
 	github.com/rs/cors v1.11.1 // indirect
 	github.com/secure-systems-lab/go-securesystemslib v0.7.0 // indirect
@@ -108,7 +110,7 @@ require (
 	golang.org/x/sys v0.26.0 // indirect
 	golang.org/x/text v0.19.0 // indirect
 	golang.org/x/tools v0.24.0 // indirect
-	google.golang.org/genproto/googleapis/rpc v0.0.0-20240822170219-fc7c04adadcd // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20240903143218-8af14fe29dc1 // indirect
 	google.golang.org/grpc v1.67.1 // indirect
 	gopkg.in/ini.v1 v1.67.0 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
@@ -130,4 +132,6 @@ replace github.com/open-telemetry/opentelemetry-collector-contrib/pkg/golden =>
 
 replace github.com/open-telemetry/opentelemetry-collector-contrib/pkg/pdatautil => ../../pkg/pdatautil
 
+replace github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/zipkin => ../../pkg/translator/zipkin
+
 replace github.com/open-telemetry/opentelemetry-collector-contrib/internal/coreinternal => ../../internal/coreinternal

receiver/datadogreceiver/internal/translator/traces_translator.go

@@ -22,6 +22,7 @@ import (
 	semconv "go.opentelemetry.io/collector/semconv/v1.16.0"
 	"google.golang.org/protobuf/proto"
 
+	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/zipkin/zipkinv2"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/datadogreceiver/internal/translator/header"
 )
 
@@ -98,6 +99,8 @@ func ToTraces(payload *pb.TracerPayload, req *http.Request) ptrace.Traces {
 			}
 			newSpan := slice.AppendEmpty()
 
+			_ = zipkinv2.TagsToSpanLinks(span.GetMeta(), newSpan.Links())
+
 			newSpan.SetTraceID(uInt64ToTraceID(0, span.TraceID))
 			newSpan.SetSpanID(uInt64ToSpanID(span.SpanID))
 			newSpan.SetStartTimestamp(pcommon.Timestamp(span.Start))