Add Zipkin example (#917)

examples/CMakeLists.txt

@@ -8,6 +8,9 @@ endif()
 if(WITH_JAEGER)
   add_subdirectory(jaeger)
 endif()
+if(WITH_ZIPKIN)
+  add_subdirectory(zipkin)
+endif()
 add_subdirectory(plugin)
 add_subdirectory(simple)
 add_subdirectory(batch)

examples/zipkin/CMakeLists.txt

@@ -0,0 +1,10 @@
+include_directories(${CMAKE_SOURCE_DIR}/exporters/zipkin/include)
+
+add_library(zipkin_foo_library foo_library/foo_library.cc)
+target_link_libraries(zipkin_foo_library ${CMAKE_THREAD_LIBS_INIT}
+                      opentelemetry_api)
+
+add_executable(example_zipkin main.cc)
+target_link_libraries(
+  example_zipkin ${CMAKE_THREAD_LIBS_INIT} zipkin_foo_library
+  opentelemetry_trace opentelemetry_exporter_zipkin_trace)

examples/zipkin/README.md

@@ -0,0 +1,31 @@
+# Zipkin Exporter Example
+
+This is an example of how to use the Zipkin exporter.
+
+The application in `main.cc` initializes an `ZipkinExporter` instance and uses it to
+register a tracer provider from the [OpenTelemetry SDK](https://github.com/open-telemetry/opentelemetry-cpp).
+The application then calls a `foo_library` which has been instrumented using the [OpenTelemetry
+API](https://github.com/open-telemetry/opentelemetry-cpp/tree/main/api).
+
+Resulting spans are exported to the Zipkin server using the Zipkin exporter.
+
+Note that the Zipkin exporter connects to the server at `localhost:9411` by
+default.
+
+## Running Zipkin server locally
+
+The quick way to run the Zipkin server is using Docker container :
+
+``console
+
+$ docker run -d -p 9411:9411 openzipkin/zipkin
+
+``
+
+## Running Zipkin example
+
+Build this example using instructions in [INSTALL.md](../../INSTALL.md).
+
+## Viewing the traces
+
+Please visit the Zipkin UI endpoint `http://localhost:9411`

examples/zipkin/foo_library/foo_library.cc

@@ -0,0 +1,37 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#include "opentelemetry/sdk/version/version.h"
+#include "opentelemetry/trace/provider.h"
+
+namespace trace = opentelemetry::trace;
+namespace nostd = opentelemetry::nostd;
+
+namespace
+{
+nostd::shared_ptr<trace::Tracer> get_tracer()
+{
+  auto provider = trace::Provider::GetTracerProvider();
+  return provider->GetTracer("foo_library", OPENTELEMETRY_SDK_VERSION);
+}
+
+void f1()
+{
+  auto scoped_span = trace::Scope(get_tracer()->StartSpan("f1"));
+}
+
+void f2()
+{
+  auto scoped_span = trace::Scope(get_tracer()->StartSpan("f2"));
+
+  f1();
+  f1();
+}
+}  // namespace
+
+void foo_library()
+{
+  auto scoped_span = trace::Scope(get_tracer()->StartSpan("library"));
+
+  f2();
+}

examples/zipkin/foo_library/foo_library.h

@@ -0,0 +1,6 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#pragma once
+
+void foo_library();

examples/zipkin/main.cc

@@ -0,0 +1,45 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#include "opentelemetry/exporters/zipkin/zipkin_exporter.h"
+#include "opentelemetry/sdk/trace/simple_processor.h"
+#include "opentelemetry/sdk/trace/tracer_provider.h"
+#include "opentelemetry/trace/provider.h"
+
+#include "foo_library/foo_library.h"
+
+namespace trace    = opentelemetry::trace;
+namespace nostd    = opentelemetry::nostd;
+namespace sdktrace = opentelemetry::sdk::trace;
+namespace zipkin   = opentelemetry::exporter::zipkin;
+
+namespace
+{
+opentelemetry::exporter::zipkin::ZipkinExporterOptions opts;
+void InitTracer()
+{
+  // Create zipkin exporter instance
+  opentelemetry::sdk::resource::ResourceAttributes attributes = {
+      {"service.name", "zipkin_demo_service"}};
+  auto resource  = opentelemetry::sdk::resource::Resource::Create(attributes);
+  auto exporter  = std::unique_ptr<sdktrace::SpanExporter>(new zipkin::ZipkinExporter(opts));
+  auto processor = std::unique_ptr<sdktrace::SpanProcessor>(
+      new sdktrace::SimpleSpanProcessor(std::move(exporter)));
+  auto provider = nostd::shared_ptr<trace::TracerProvider>(
+      new sdktrace::TracerProvider(std::move(processor), resource));
+  // Set the global trace provider
+  trace::Provider::SetTracerProvider(provider);
+}
+}  // namespace
+
+int main(int argc, char *argv[])
+{
+  if (argc == 2)
+  {
+    opts.endpoint = argv[1];
+  }
+  // Removing this line will leave the default noop TracerProvider in place.
+  InitTracer();
+
+  foo_library();
+}