[DEPRECATION] Deprecate ZPAGES

CHANGELOG.md

@@ -15,6 +15,9 @@ Increment the:
 
 ## [Unreleased]
 
+* [DEPRECATION] Deprecate ZPAGES
+  [#2291](https://github.com/open-telemetry/opentelemetry-cpp/pull/2291)
+
 ## [1.11.0] 2023-08-21
 
 * [BUILD] Fix more cases for symbol name for 32-bit win32 DLL build

CMakeLists.txt

@@ -185,7 +185,8 @@ option(WITH_PROMETHEUS "Whether to include the Prometheus Client in the SDK"
 option(WITH_ELASTICSEARCH
        "Whether to include the Elasticsearch Client in the SDK" OFF)
 
-option(WITH_ZPAGES "Whether to include the Zpages Server in the SDK" OFF)
+option(WITH_ZPAGES
+       "DEPRECATED - Whether to include the Zpages Server in the SDK" OFF)
 
 option(WITH_NO_GETENV "Whether the platform supports environment variables" OFF)
 
@@ -258,6 +259,14 @@ option(WITH_OTLP_HTTP_SSL_TLS_PREVIEW
 option(WITH_METRICS_EXEMPLAR_PREVIEW
        "Whether to enable exemplar within metrics" OFF)
 
+if(WITH_ZPAGES)
+  if(WITH_NO_DEPRECATED_CODE)
+    message(FATAL_ERROR "WITH_ZPAGES is DEPRECATED.")
+  else()
+    message(WARNING "WITH_ZPAGES is DEPRECATED.")
+  endif()
+endif()
+
 #
 # Verify options dependencies
 #

DEPRECATED.md

@@ -151,7 +151,59 @@ N/A
 
 ## [opentelemetry-cpp Exporter]
 
-N/A
+### ZPages exporter
+
+#### Announcement (ZPages)
+
+* Version: 1.11.0
+* Date: 2023-09-01
+* PR: [DEPRECATION] Deprecate ZPAGES
+  [#2291](https://github.com/open-telemetry/opentelemetry-cpp/pull/2291)
+
+#### Motivation (ZPages)
+
+The ZPages specification itself was introduced in 2020,
+and has been experimental ever since,
+not getting a lot of attention, and never reaching a stable status.
+
+Several other opentelemetry projects have implemented support for zpages,
+only to later deprecate and then remove the zpages implementation (Java,
+C#), abandoning the zpages feature.
+
+In this context, it does not make sense to continue to maintain the zpages
+code in opentelemetry-cpp.
+
+#### Scope (ZPages)
+
+The following are deprecated and planned for removal:
+
+* all the API headers located under `ext/include/opentelemetry/ext/zpages/`, including:
+  * the C++ class `ThreadsafeSpanData`
+  * the C++ class `TracezDataAggregator`
+  * the C++ class `TracezHttpServer`
+  * the C++ class `TracezSpanProcessor`
+  * the C++ class `TracezSharedData`
+  * the C++ class `ZPages`
+  * the C++ class `zPagesHttpServer`
+* all the code and doc located under `ext/src/zpages/`
+* all the tests located under `ext/test/zpages/`
+* the zpages exporter library(`opentelemetry_zpages`)
+* the zpages build options in CMake (`WITH_ZPAGES`)
+
+#### Mitigation (ZPages)
+
+Consider using a different exporter,
+for example the OTLP exporter (both OTLP HTTP and OTLP GRPC are supported),
+to expose trace data to a separate trace backend.
+
+Note that this changes the access pattern:
+
+* with zpages, data is only available locally (in process)
+* with other exporters, data is available externally (not in process)
+
+#### Planned removal (ZPages)
+
+* Date: December, 2023
 
 ## [Documentation]