feat(contrib/lovoo/goka): add goka integration with APM and DSM support

Add a new contrib package instrumenting github.com/lovoo/goka with both
Datadog APM distributed tracing and Data Streams Monitoring in a single
integration.

goka builds its consumer group on top of IBM/sarama but owns the
sarama.ConsumerGroupHandler internally, so the contrib/IBM/sarama
integration cannot attach. This package instruments through goka's public
extension points instead, requiring no changes to goka:

- NewTracer + WrapContext (goka.WithContextWrapper) sets the inbound DSM
  checkpoint and returns a context whose Emit/Loopback propagate the active
  consume span and a DSM outbound checkpoint into the emitted headers.
- WrapCallback runs each input message inside a kafka.consume span,
  finishing it around the callback (panics recovered and error-tagged) and
  recording the DSM commit offset on success, honoring ctx.DeferCommit.
- No kafka.produce span is created: goka.Context.Emit is asynchronous with
  no completion handle, so trace continuity is preserved by propagating the
  consume span through the outbound headers instead.
- EmitHeaders covers the standalone goka.Emitter path.
- WithService, WithDataStreams, and WithLoopSuffix options; a single header
  carrier satisfies both the tracer and datastreams TextMap interfaces.

Register PackageLovooGoka in instrumentation/packages.go and
contribIntegrations in ddtrace/tracer/option.go. Includes unit tests
(carrier round-trip, DSM no-op when disabled, span parent/child linkage,
error tagging, emit/loopback injection, DeferCommit, context delegation)
and an INTEGRATION-gated end-to-end test.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: anapsix

contrib/lovoo/goka/carrier.go

@@ -0,0 +1,49 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2016 Datadog, Inc.
+
+package goka
+
+import (
+	"github.com/lovoo/goka"
+
+	"github.com/DataDog/dd-trace-go/v2/datastreams"
+	"github.com/DataDog/dd-trace-go/v2/ddtrace/tracer"
+)
+
+// gokaHeadersCarrier adapts goka.Headers (map[string][]byte) to the text-map
+// interfaces used by both APM trace propagation (tracer.Extract/Inject) and Data
+// Streams Monitoring (datastreams.ExtractFromBase64Carrier/InjectToBase64Carrier).
+// A single carrier serves both because the four interfaces share the same method
+// shapes. The carrier shares the underlying map, so Set mutates the goka.Headers
+// it wraps.
+type gokaHeadersCarrier goka.Headers
+
+var (
+	_ tracer.TextMapReader      = gokaHeadersCarrier(nil)
+	_ tracer.TextMapWriter      = gokaHeadersCarrier(nil)
+	_ datastreams.TextMapReader = gokaHeadersCarrier(nil)
+	_ datastreams.TextMapWriter = gokaHeadersCarrier(nil)
+)
+
+// ForeachKey implements tracer.TextMapReader and datastreams.TextMapReader.
+func (c gokaHeadersCarrier) ForeachKey(handler func(key, val string) error) error {
+	for k, v := range c {
+		if err := handler(k, string(v)); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Set implements tracer.TextMapWriter and datastreams.TextMapWriter.
+func (c gokaHeadersCarrier) Set(key, val string) {
+	c[key] = []byte(val)
+}
+
+// ExtractSpanContext extracts the span context propagated in a goka message's
+// headers, allowing callers to create manual child spans.
+func ExtractSpanContext(headers goka.Headers) (*tracer.SpanContext, error) {
+	return tracer.Extract(gokaHeadersCarrier(headers))
+}

contrib/lovoo/goka/example_test.go

@@ -0,0 +1,44 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2016 Datadog, Inc.
+
+package goka_test
+
+import (
+	"log"
+
+	gokatrace "github.com/DataDog/dd-trace-go/contrib/lovoo/goka/v2"
+
+	"github.com/lovoo/goka"
+	"github.com/lovoo/goka/codec"
+)
+
+func Example() {
+	tr := gokatrace.NewTracer(
+		gokatrace.WithService("orders-processor"),
+		gokatrace.WithDataStreams(),
+	)
+
+	// handle processes an input message. Because the callback is wrapped, it runs
+	// inside a "kafka.consume" span, and ctx.Emit continues the trace downstream.
+	handle := func(ctx goka.Context, msg any) {
+		ctx.Emit("orders-enriched", ctx.Key(), msg)
+	}
+
+	g := goka.DefineGroup(
+		"orders",
+		goka.Input("orders", new(codec.String), tr.WrapCallback(handle)),
+		goka.Output("orders-enriched", new(codec.String)),
+	)
+
+	p, err := goka.NewProcessor(
+		[]string{"localhost:9092"},
+		g,
+		goka.WithContextWrapper(tr.WrapContext),
+	)
+	if err != nil {
+		log.Fatal(err)
+	}
+	_ = p
+}

contrib/lovoo/goka/go.mod

@@ -0,0 +1,103 @@
+module github.com/DataDog/dd-trace-go/contrib/lovoo/goka/v2
+
+go 1.25.0
+
+require (
+	github.com/DataDog/dd-trace-go/v2 v2.11.0-dev
+	github.com/lovoo/goka v1.1.8
+	github.com/stretchr/testify v1.11.1
+)
+
+require (
+	github.com/DataDog/datadog-agent/comp/core/tagger/origindetection v0.79.0 // indirect
+	github.com/DataDog/datadog-agent/pkg/obfuscate v0.79.0 // indirect
+	github.com/DataDog/datadog-agent/pkg/opentelemetry-mapping-go/otlp/attributes v0.79.0 // indirect
+	github.com/DataDog/datadog-agent/pkg/proto v0.79.0 // indirect
+	github.com/DataDog/datadog-agent/pkg/remoteconfig/state v0.79.0 // indirect
+	github.com/DataDog/datadog-agent/pkg/trace v0.79.0 // indirect
+	github.com/DataDog/datadog-agent/pkg/trace/log v0.79.0 // indirect
+	github.com/DataDog/datadog-agent/pkg/trace/stats v0.79.0 // indirect
+	github.com/DataDog/datadog-agent/pkg/trace/traceutil v0.79.0 // indirect
+	github.com/DataDog/datadog-go/v5 v5.8.3 // indirect
+	github.com/DataDog/go-libddwaf/v5 v5.0.0 // indirect
+	github.com/DataDog/go-runtime-metrics-internal v0.0.4-0.20260217080614-b0f4edc38a6d // indirect
+	github.com/DataDog/go-sqllexer v0.2.1 // indirect
+	github.com/DataDog/go-tuf v1.1.1-0.5.2 // indirect
+	github.com/DataDog/sketches-go v1.4.8 // indirect
+	github.com/Microsoft/go-winio v0.6.2 // indirect
+	github.com/Shopify/sarama v1.37.2 // indirect
+	github.com/cenkalti/backoff/v5 v5.0.3 // 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 v1.1.2-0.20180830191138-d8f796af33cc // indirect
+	github.com/dustin/go-humanize v1.0.1 // indirect
+	github.com/eapache/go-resiliency v1.3.0 // indirect
+	github.com/eapache/go-xerial-snappy v0.0.0-20180814174437-776d5712da21 // indirect
+	github.com/eapache/queue v1.1.0 // indirect
+	github.com/ebitengine/purego v0.10.0 // indirect
+	github.com/go-ole/go-ole v1.3.0 // indirect
+	github.com/go-stack/stack v1.8.1 // indirect
+	github.com/golang/mock v1.7.0-rc.1 // indirect
+	github.com/golang/snappy v0.0.4 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/hashicorp/errwrap v1.1.0 // indirect
+	github.com/hashicorp/go-multierror v1.1.1 // indirect
+	github.com/hashicorp/go-uuid v1.0.3 // indirect
+	github.com/hashicorp/go-version v1.9.0 // indirect
+	github.com/jcmturner/aescts/v2 v2.0.0 // indirect
+	github.com/jcmturner/dnsutils/v2 v2.0.0 // indirect
+	github.com/jcmturner/gofork v1.7.6 // indirect
+	github.com/jcmturner/gokrb5/v8 v8.4.3 // indirect
+	github.com/jcmturner/rpc/v2 v2.0.3 // indirect
+	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/klauspost/compress v1.18.6 // indirect
+	github.com/klauspost/cpuid/v2 v2.3.0 // indirect
+	github.com/linkdata/deadlock v0.5.5 // indirect
+	github.com/lufia/plan9stats v0.0.0-20260216142805-b3301c5f2a88 // indirect
+	github.com/minio/simdjson-go v0.4.5 // indirect
+	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
+	github.com/modern-go/reflect2 v1.0.3-0.20250322232337-35a7c28c31ee // indirect
+	github.com/outcaste-io/ristretto v0.2.3 // indirect
+	github.com/petermattis/goid v0.0.0-20260226131333-17d1149c6ac6 // indirect
+	github.com/philhofer/fwd v1.2.0 // indirect
+	github.com/pierrec/lz4/v4 v4.1.17 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10 // indirect
+	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
+	github.com/power-devops/perfstat v0.0.0-20240221224432-82ca36839d55 // indirect
+	github.com/puzpuzpuz/xsync/v4 v4.5.0 // indirect
+	github.com/rcrowley/go-metrics v0.0.0-20201227073835-cf1acfcdf475 // indirect
+	github.com/secure-systems-lab/go-securesystemslib v0.10.0 // indirect
+	github.com/shirou/gopsutil/v4 v4.26.3 // indirect
+	github.com/syndtr/goleveldb v1.0.1-0.20220721030215-126854af5e6d // indirect
+	github.com/tinylib/msgp v1.6.3 // indirect
+	github.com/tklauser/go-sysconf v0.3.16 // indirect
+	github.com/tklauser/numcpus v0.11.0 // indirect
+	github.com/trailofbits/go-mutexasserts v0.0.0-20250514102930-c1f3d2e37561 // indirect
+	github.com/yusufpapurcu/wmi v1.2.4 // indirect
+	go.opentelemetry.io/collector/component v1.56.0 // indirect
+	go.opentelemetry.io/collector/featuregate v1.56.0 // indirect
+	go.opentelemetry.io/collector/pdata v1.56.0 // indirect
+	go.opentelemetry.io/collector/pdata/pprofile v0.150.0 // indirect
+	go.opentelemetry.io/otel v1.43.0 // indirect
+	go.opentelemetry.io/otel/metric v1.43.0 // indirect
+	go.opentelemetry.io/otel/trace v1.43.0 // indirect
+	go.opentelemetry.io/proto/otlp v1.10.0 // indirect
+	go.uber.org/atomic v1.11.0 // indirect
+	go.uber.org/multierr v1.11.0 // indirect
+	go.uber.org/zap v1.27.1 // indirect
+	go.yaml.in/yaml/v3 v3.0.4 // indirect
+	golang.org/x/crypto v0.52.0 // indirect
+	golang.org/x/exp v0.0.0-20260209203927-2842357ff358 // indirect
+	golang.org/x/mod v0.35.0 // indirect
+	golang.org/x/net v0.55.0 // indirect
+	golang.org/x/sync v0.20.0 // indirect
+	golang.org/x/sys v0.45.0 // indirect
+	golang.org/x/time v0.15.0 // indirect
+	golang.org/x/xerrors v0.0.0-20240903120638-7835f813f4da // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20260406210006-6f92a3bedf2d // indirect
+	google.golang.org/protobuf v1.36.11 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
+
+replace github.com/DataDog/dd-trace-go/v2 => ../../..