[SDK] Support OTEL_SDK_DISABLED environment variable

CHANGELOG.md

@@ -18,6 +18,47 @@ Increment the:
 * [SDK] Add tracer scope configurator
   [#3137](https://github.com/open-telemetry/opentelemetry-cpp/pull/3137)
 
+* [SDK] Support OTEL_SDK_DISABLED environment variable
+  [#3245](https://github.com/open-telemetry/opentelemetry-cpp/pull/3245)
+
+Important changes:
+
+* [SDK] Support OTEL_SDK_DISABLED environment variable
+  [#3245](https://github.com/open-telemetry/opentelemetry-cpp/pull/3245)
+
+  * The SDK now exposes the following new methods:
+
+    * opentelemetry::sdk::trace::Provider::SetTracerProvider()
+    * opentelemetry::sdk::metrics::Provider::SetMeterProvider()
+    * opentelemetry::sdk::logs::Provider::SetLoggerProvider()
+
+  * These methods do support the `OTEL_SDK_DISABLED` environment variable,
+    unlike the corresponding existing API Provider classes.
+
+  * Applications are encouraged to migrate from the API to the SDK
+    `Provider` classes, to benefit from this feature.
+
+  * Note that the API methods will no longer be public starting
+    with OPENTELEMETRY_ABI_VERSION >= 2, only the SDK methods will
+    be available then.
+
+  * All the example code has been updated to reflect the new usage.
+
+Breaking changes:
+
+* [SDK] Support OTEL_SDK_DISABLED environment variable
+  [#3245](https://github.com/open-telemetry/opentelemetry-cpp/pull/3245)
+
+  * The following existing API methods are no longer public
+    starting with OPENTELEMETRY_ABI_VERSION >= 2.
+
+    * opentelemetry::trace::Provider::SetTracerProvider()
+    * opentelemetry::metrics::Provider::SetMeterProvider()
+    * opentelemetry::logs::Provider::SetLoggerProvider()
+
+  * Applications should use the corresponding SDK methods,
+    already available in every ABI version.
+
 ## [1.19 2025-01-22]
 
 * [PROMETHEUS_EXPORTER] Fix default for emitting otel_scope attributes

api/include/opentelemetry/logs/provider.h

@@ -12,6 +12,17 @@
 #include "opentelemetry/version.h"
 
 OPENTELEMETRY_BEGIN_NAMESPACE
+namespace sdk
+{
+namespace logs
+{
+// The forward declaration is sufficient,
+// we do not want a API -> SDK dependency.
+// IWYU pragma: no_include "opentelemetry/sdk/logs/provider.h"
+class Provider;
+}  // namespace logs
+}  // namespace sdk
+
 namespace logs
 {
 
@@ -36,15 +47,6 @@ class OPENTELEMETRY_EXPORT Provider
     return nostd::shared_ptr<LoggerProvider>(GetProvider());
   }
 
-  /**
-   * Changes the singleton LoggerProvider.
-   */
-  static void SetLoggerProvider(const nostd::shared_ptr<LoggerProvider> &tp) noexcept
-  {
-    std::lock_guard<common::SpinLockMutex> guard(GetLock());
-    GetProvider() = tp;
-  }
-
   /**
    * Returns the singleton EventLoggerProvider.
    *
@@ -66,7 +68,23 @@ class OPENTELEMETRY_EXPORT Provider
     GetEventProvider() = tp;
   }
 
+#if OPENTELEMETRY_ABI_VERSION_NO >= 2
 private:
+#endif /* OPENTELEMETRY_ABI_VERSION_NO */
+
+  /**
+   * Changes the singleton LoggerProvider.
+   */
+  static void SetLoggerProvider(const nostd::shared_ptr<LoggerProvider> &tp) noexcept
+  {
+    std::lock_guard<common::SpinLockMutex> guard(GetLock());
+    GetProvider() = tp;
+  }
+
+private:
+  /* The SDK is allowed to change the singleton in the API. */
+  friend class opentelemetry::sdk::logs::Provider;
+
   OPENTELEMETRY_API_SINGLETON static nostd::shared_ptr<LoggerProvider> &GetProvider() noexcept
   {
     static nostd::shared_ptr<LoggerProvider> provider(new NoopLoggerProvider);

api/include/opentelemetry/metrics/provider.h

@@ -5,17 +5,26 @@
 
 #include <mutex>
 
-#include "opentelemetry/common/macros.h"
 #include "opentelemetry/common/spin_lock_mutex.h"
+#include "opentelemetry/metrics/meter_provider.h"
 #include "opentelemetry/metrics/noop.h"
 #include "opentelemetry/nostd/shared_ptr.h"
 #include "opentelemetry/version.h"
 
 OPENTELEMETRY_BEGIN_NAMESPACE
+namespace sdk
+{
 namespace metrics
 {
+// The forward declaration is sufficient,
+// we do not want a API -> SDK dependency.
+// IWYU pragma: no_include "opentelemetry/sdk/metrics/provider.h"
+class Provider;  // IWYU pragma: keep
+}  // namespace metrics
+}  // namespace sdk
 
-class MeterProvider;
+namespace metrics
+{
 
 /**
  * Stores the singleton global MeterProvider.
@@ -35,6 +44,10 @@ class Provider
     return nostd::shared_ptr<MeterProvider>(GetProvider());
   }
 
+#if OPENTELEMETRY_ABI_VERSION_NO >= 2
+private:
+#endif /* OPENTELEMETRY_ABI_VERSION_NO */
+
   /**
    * Changes the singleton MeterProvider.
    */
@@ -45,6 +58,9 @@ class Provider
   }
 
 private:
+  /* The SDK is allowed to change the singleton in the API. */
+  friend class opentelemetry::sdk::metrics::Provider;
+
   OPENTELEMETRY_API_SINGLETON static nostd::shared_ptr<MeterProvider> &GetProvider() noexcept
   {
     static nostd::shared_ptr<MeterProvider> provider(new NoopMeterProvider);

api/include/opentelemetry/trace/provider.h

@@ -12,6 +12,17 @@
 #include "opentelemetry/version.h"
 
 OPENTELEMETRY_BEGIN_NAMESPACE
+namespace sdk
+{
+namespace trace
+{
+// The forward declaration is sufficient,
+// we do not want a API -> SDK dependency.
+// IWYU pragma: no_include "opentelemetry/sdk/trace/provider.h"
+class Provider;  // IWYU pragma: keep
+}  // namespace trace
+}  // namespace sdk
+
 namespace trace
 {
 
@@ -33,6 +44,10 @@ class OPENTELEMETRY_EXPORT Provider
     return nostd::shared_ptr<TracerProvider>(GetProvider());
   }
 
+#if OPENTELEMETRY_ABI_VERSION_NO >= 2
+private:
+#endif /* OPENTELEMETRY_ABI_VERSION_NO */
+
   /**
    * Changes the singleton TracerProvider.
    */
@@ -43,6 +58,9 @@ class OPENTELEMETRY_EXPORT Provider
   }
 
 private:
+  /* The SDK is allowed to change the singleton in the API. */
+  friend class opentelemetry::sdk::trace::Provider;
+
   OPENTELEMETRY_API_SINGLETON static nostd::shared_ptr<TracerProvider> &GetProvider() noexcept
   {
     static nostd::shared_ptr<TracerProvider> provider(new NoopTracerProvider);

api/test/CMakeLists.txt

@@ -10,7 +10,3 @@ add_subdirectory(metrics)
 add_subdirectory(logs)
 add_subdirectory(common)
 add_subdirectory(baggage)
-
-if(NOT OPENTELEMETRY_SKIP_DYNAMIC_LOADING_TESTS)
-  add_subdirectory(singleton)
-endif()

api/test/logs/logger_test.cc

@@ -220,6 +220,7 @@ class TestProvider : public LoggerProvider
   }
 };
 
+#if OPENTELEMETRY_ABI_VERSION_NO == 1
 TEST(Logger, PushLoggerImplementation)
 {
   // Push the new loggerprovider class into the global singleton
@@ -233,3 +234,4 @@ TEST(Logger, PushLoggerImplementation)
   auto logger = lp->GetLogger("TestLogger", "opentelelemtry_library", "", schema_url);
   ASSERT_EQ("test logger", logger->GetName());
 }
+#endif /* OPENTELEMETRY_ABI_VERSION_NO */

api/test/logs/provider_test.cc

@@ -40,6 +40,7 @@ TEST(Provider, GetLoggerProviderDefault)
   EXPECT_NE(nullptr, tf);
 }
 
+#if OPENTELEMETRY_ABI_VERSION_NO == 1
 TEST(Provider, SetLoggerProvider)
 {
   auto tf = shared_ptr<LoggerProvider>(new TestProvider());
@@ -56,6 +57,7 @@ TEST(Provider, MultipleLoggerProviders)
 
   ASSERT_NE(Provider::GetLoggerProvider(), tf);
 }
+#endif /* OPENTELEMETRY_ABI_VERSION_NO */
 
 TEST(Provider, GetLogger)
 {

api/test/metrics/meter_provider_test.cc

@@ -3,6 +3,7 @@
 
 #include <gtest/gtest.h>
 
+#include "opentelemetry/metrics/meter_provider.h"
 #include "opentelemetry/metrics/noop.h"
 #include "opentelemetry/metrics/provider.h"
 #include "opentelemetry/nostd/shared_ptr.h"
@@ -17,6 +18,7 @@ TEST(Provider, GetMeterProviderDefault)
   EXPECT_NE(nullptr, tf);
 }
 
+#if OPENTELEMETRY_ABI_VERSION_NO == 1
 TEST(Provider, SetMeterProvider)
 {
   auto tf = opentelemetry::nostd::shared_ptr<MeterProvider>(new NoopMeterProvider());
@@ -33,3 +35,4 @@ TEST(Provider, MultipleMeterProviders)
 
   ASSERT_NE(Provider::GetMeterProvider(), tf);
 }
+#endif /* OPENTELEMETRY_ABI_VERSION_NO */

api/test/trace/provider_test.cc

@@ -42,9 +42,11 @@ TEST(Provider, GetTracerProviderDefault)
   EXPECT_NE(nullptr, tf);
 }
 
+#if OPENTELEMETRY_ABI_VERSION_NO == 1
 TEST(Provider, SetTracerProvider)
 {
   auto tf = nostd::shared_ptr<TracerProvider>(new TestProvider());
   Provider::SetTracerProvider(tf);
   ASSERT_EQ(tf, Provider::GetTracerProvider());
 }
+#endif /* OPENTELEMETRY_ABI_VERSION_NO */

examples/batch/main.cc

@@ -16,6 +16,7 @@
 #include "opentelemetry/sdk/trace/batch_span_processor_options.h"
 #include "opentelemetry/sdk/trace/exporter.h"
 #include "opentelemetry/sdk/trace/processor.h"
+#include "opentelemetry/sdk/trace/provider.h"
 #include "opentelemetry/sdk/trace/tracer_provider.h"
 #include "opentelemetry/sdk/trace/tracer_provider_factory.h"
 #include "opentelemetry/trace/provider.h"
@@ -56,13 +57,13 @@ void InitTracer()
       trace_sdk::TracerProviderFactory::Create(std::move(processor), resource);
 
   // Set the global trace provider.
-  trace_api::Provider::SetTracerProvider(provider);
+  trace_sdk::Provider::SetTracerProvider(provider);
 }
 
 void CleanupTracer()
 {
   std::shared_ptr<opentelemetry::trace::TracerProvider> none;
-  trace_api::Provider::SetTracerProvider(none);
+  trace_sdk::Provider::SetTracerProvider(none);
 }
 
 opentelemetry::nostd::shared_ptr<trace_api::Tracer> get_tracer()

examples/grpc/tracer_common.h

@@ -9,6 +9,7 @@
 #include "opentelemetry/nostd/shared_ptr.h"
 #include "opentelemetry/sdk/trace/exporter.h"
 #include "opentelemetry/sdk/trace/processor.h"
+#include "opentelemetry/sdk/trace/provider.h"
 #include "opentelemetry/sdk/trace/simple_processor_factory.h"
 #include "opentelemetry/sdk/trace/tracer_context.h"
 #include "opentelemetry/sdk/trace/tracer_context_factory.h"
@@ -85,7 +86,7 @@ void InitTracer()
   std::shared_ptr<opentelemetry::trace::TracerProvider> provider =
       opentelemetry::sdk::trace::TracerProviderFactory::Create(std::move(context));
   // Set the global trace provider
-  opentelemetry::trace::Provider::SetTracerProvider(provider);
+  opentelemetry::sdk::trace::Provider::SetTracerProvider(provider);
 
   // set global propagator
   opentelemetry::context::propagation::GlobalTextMapPropagator::SetGlobalPropagator(
@@ -96,7 +97,7 @@ void InitTracer()
 void CleanupTracer()
 {
   std::shared_ptr<opentelemetry::trace::TracerProvider> none;
-  opentelemetry::trace::Provider::SetTracerProvider(none);
+  opentelemetry::sdk::trace::Provider::SetTracerProvider(none);
 }
 
 opentelemetry::nostd::shared_ptr<opentelemetry::trace::Tracer> get_tracer(std::string tracer_name)

examples/http/tracer_common.h

@@ -3,24 +3,24 @@
 
 #pragma once
 
+#include <cstring>
+#include <iostream>
+#include <vector>
+
+#include "opentelemetry/context/propagation/global_propagator.h"
+#include "opentelemetry/context/propagation/text_map_propagator.h"
 #include "opentelemetry/exporters/ostream/span_exporter_factory.h"
+#include "opentelemetry/ext/http/client/http_client.h"
+#include "opentelemetry/nostd/shared_ptr.h"
 #include "opentelemetry/sdk/trace/exporter.h"
 #include "opentelemetry/sdk/trace/processor.h"
+#include "opentelemetry/sdk/trace/provider.h"
 #include "opentelemetry/sdk/trace/simple_processor_factory.h"
 #include "opentelemetry/sdk/trace/tracer_context.h"
 #include "opentelemetry/sdk/trace/tracer_context_factory.h"
 #include "opentelemetry/sdk/trace/tracer_provider_factory.h"
-#include "opentelemetry/trace/provider.h"
-
-#include "opentelemetry/context/propagation/global_propagator.h"
-#include "opentelemetry/context/propagation/text_map_propagator.h"
 #include "opentelemetry/trace/propagation/http_trace_context.h"
-
-#include <cstring>
-#include <iostream>
-#include <vector>
-#include "opentelemetry/ext/http/client/http_client.h"
-#include "opentelemetry/nostd/shared_ptr.h"
+#include "opentelemetry/trace/provider.h"
 
 namespace
 {
@@ -75,7 +75,7 @@ void InitTracer()
   std::shared_ptr<opentelemetry::trace::TracerProvider> provider =
       opentelemetry::sdk::trace::TracerProviderFactory::Create(std::move(context));
   // Set the global trace provider
-  opentelemetry::trace::Provider::SetTracerProvider(provider);
+  opentelemetry::sdk::trace::Provider::SetTracerProvider(provider);
 
   // set global propagator
   opentelemetry::context::propagation::GlobalTextMapPropagator::SetGlobalPropagator(
@@ -86,7 +86,7 @@ void InitTracer()
 void CleanupTracer()
 {
   std::shared_ptr<opentelemetry::trace::TracerProvider> none;
-  opentelemetry::trace::Provider::SetTracerProvider(none);
+  opentelemetry::sdk::trace::Provider::SetTracerProvider(none);
 }
 
 opentelemetry::nostd::shared_ptr<opentelemetry::trace::Tracer> get_tracer(std::string tracer_name)