Deprecate Zipkin exporter

CHANGELOG.md

@@ -11,6 +11,9 @@ release.
 
 ### Traces
 
+- Deprecate Zipkin exporter document and make exporter implementation optional
+  ([#4715](https://github.com/open-telemetry/opentelemetry-specification/pull/4715/))
+
 ### Metrics
 
 - `AlignedHistogramBucketExemplarReservoir` SHOULD use a time-weighted algorithm.

spec-compliance-matrix.md

@@ -334,8 +334,8 @@ Disclaimer: Declarative configuration is currently in Development status - work
 | **[Zipkin](specification/trace/sdk_exporters/zipkin.md)** | Optional | Go | Java | JS | Python | Ruby | Erlang | PHP | Rust | C++ | .NET | Swift |
 | Zipkin V1 JSON | X | - | + |  | + | - | - | - | - | - | - | - |
 | Zipkin V1 Thrift | X | - | + |  | [-][py1174] | - | - | - | - | - | - | - |
-| Zipkin V2 JSON | * | + | + |  | + | + | - | + | + | + | + | + |
-| Zipkin V2 Protobuf | * | - | + |  | + | - | + | - | - | - | - | - |
+| Zipkin V2 JSON | X | + | + |  | + | + | - | + | + | + | + | + |
+| Zipkin V2 Protobuf | X | - | + |  | + | - | + | - | - | - | - | - |
 | Service name mapping |  | + | + | + | + | + | + | + | + | + | + | + |
 | SpanKind mapping |  | + | + | + | + | + | + | + | + | + | + | + |
 | InstrumentationLibrary mapping |  | + | + | - | + | + | - | + | + | + | + | + |

spec-compliance-matrix/template.yaml

@@ -375,9 +375,9 @@ sections:
           - name: Zipkin V1 Thrift
             optional: true
           - name: Zipkin V2 JSON
-            optional_one_of_group_is_required: true
+            optional: true
           - name: Zipkin V2 Protobuf
-            optional_one_of_group_is_required: true
+            optional: true
           - name: Service name mapping
           - name: SpanKind mapping
           - name: InstrumentationLibrary mapping

specification/configuration/sdk-environment-variables.md

@@ -270,6 +270,8 @@ See [OpenTelemetry Protocol Exporter Configuration Options](../protocol/exporter
 
 ## Zipkin Exporter
 
+**Status**: [Deprecated](../../document-status.md)
+
 | Name                          | Description                                                                        | Default                              | Type        |
 |-------------------------------|------------------------------------------------------------------------------------|--------------------------------------|-------------|
 | OTEL_EXPORTER_ZIPKIN_ENDPOINT | Endpoint for Zipkin traces                                                         | `http://localhost:9411/api/v2/spans` | [String][]  |

specification/trace/sdk_exporters/zipkin.md

@@ -4,7 +4,14 @@ linkTitle: Zipkin
 
 # OpenTelemetry to Zipkin Transformation
 
-**Status**: [Stable](../../document-status.md)
+**Status**: [Deprecated](../../document-status.md)
+
+_Note: This document remains here for backwards compatibility and
+will be removed in a future version. SDKs MAY include Zipkin exporters,
+but Zipkin exporter is not required.
+
+Users may export to Zipkin using [zipkin exporter](https://github.com/open-telemetry/opentelemetry-collector-contrib/tree/main/exporter/zipkinexporter) collector component or [zipkin-otel](https://github.com/openzipkin-contrib/zipkin-otel)
+Zipkin server module_
 
 This document defines the transformation between OpenTelemetry and Zipkin Spans.
 The generic transformation [rules specified here](../../common/mapping-to-non-otlp.md) also apply. If a
@@ -69,7 +76,7 @@ not work properly. OpenTelemetry doesn't provide this consistency guarantee.
 Exporter may chose to override the value for service name based on a local root
 span to improve Zipkin user experience.
 
-*Note*, the attribute `service.namespace` MUST NOT be used for the Zipkin
+_Note_, the attribute `service.namespace` MUST NOT be used for the Zipkin
 service name and should be sent as a Zipkin tag.
 
 ### SpanKind