Simple instrumented gRPC example (#729)

examples/CMakeLists.txt

@@ -1,5 +1,6 @@
 if(WITH_OTLP)
   add_subdirectory(otlp)
+  add_subdirectory(grpc)
 endif()
 if(WITH_JAEGER)
   add_subdirectory(jaeger)

examples/grpc/CMakeLists.txt

@@ -0,0 +1,48 @@
+# Proto file
+get_filename_component(proto_file "./protos/messages.proto" ABSOLUTE)
+get_filename_component(proto_file_path "${proto_file}" PATH)
+
+message("PATH:${proto_file_path}:${proto_file}")
+# Generated sources
+set(example_proto_srcs "${CMAKE_CURRENT_BINARY_DIR}/messages.pb.cc")
+set(example_proto_hdrs "${CMAKE_CURRENT_BINARY_DIR}/messages.pb.h")
+set(example_grpc_srcs "${CMAKE_CURRENT_BINARY_DIR}/messages.grpc.pb.cc")
+set(example_grpc_hdrs "${CMAKE_CURRENT_BINARY_DIR}/messages.grpc.pb.h")
+
+add_custom_command(
+  OUTPUT "${example_proto_srcs}" "${example_proto_hdrs}" "${example_grpc_srcs}"
+         "${example_grpc_hdrs}"
+  COMMAND
+    ${PROTOBUF_PROTOC_EXECUTABLE} ARGS "--grpc_out=${CMAKE_CURRENT_BINARY_DIR}"
+    "--cpp_out=${CMAKE_CURRENT_BINARY_DIR}" "--proto_path=${proto_file_path}"
+    --plugin=protoc-gen-grpc="${gRPC_CPP_PLUGIN_EXECUTABLE}" "${proto_file}")
+# DEPENDS "${proto_file}")
+
+# hw_grpc_proto
+add_library(example_grpc_proto ${example_grpc_srcs} ${example_grpc_hdrs}
+                               ${example_proto_srcs} ${example_proto_hdrs})
+
+include_directories(
+  ${CMAKE_SOURCE_DIR}/exporters/ostream/include ${CMAKE_SOURCE_DIR}/ext/include
+  ${CMAKE_SOURCE_DIR}/api/include/ ${CMAKE_SOURCE_DIR/})
+
+include_directories(${CMAKE_CURRENT_BINARY_DIR})
+
+if(TARGET protobuf::libprotobuf)
+  target_link_libraries(example_grpc_proto gRPC::grpc++ protobuf::libprotobuf)
+else()
+  target_include_directories(example_grpc_proto ${Protobuf_INCLUDE_DIRS})
+  target_link_libraries(example_grpc_proto ${Protobuf_LIBRARIES})
+endif()
+
+foreach(_target client server)
+  add_executable(${_target} "${_target}.cpp")
+  target_link_libraries(
+    ${_target}
+    example_grpc_proto
+    protobuf::libprotobuf
+    gRPC::grpc++
+    gRPC::grpc++_reflection
+    opentelemetry_trace
+    opentelemetry_exporter_ostream_span)
+endforeach()

examples/grpc/README.md

@@ -0,0 +1,99 @@
+# OpenTelemetry C++  Example
+
+## gRPC
+
+This is a simple example that demonstrates tracing a gRPC request from client to server. There is an experimental directory in this example - the code within has been commented out to prevent any conflicts. The example shows several aspects of tracing such as:
+
+* Using the `TracerProvider`
+* Implementing the TextMapCarrier
+* Context injection/extraction
+* Span Attributes
+* Span Semantic Conventions
+* Using the ostream exporter
+* Nested spans
+* W3c Trace Context Propagation (Very soon!)
+
+### Running the example
+
+1. The example uses gRPC C++ as well as Google's protocol buffers. Make sure you have installed both
+   of these packages on your system, in such a way that CMake would know how to find them with this command:
+
+    ``find_package(gRPC)``
+
+2. Build and Deploy the opentelementry-cpp as described in [INSTALL.md](../../INSTALL.md). Building the project will build all of the examples
+   and create new folders containing their executables within the 'build' directory NOT the 'examples' directory.
+
+3. Start the server from your `build/examples/grpc` directory. Both the server and client are configured to use 8800 as the default port,
+   but if you would like to use another port, you can specify that as an argument.
+
+   ```console
+   $ ./server [port_num]
+    Server listening on port: 0.0.0.0:8800
+   ```
+
+4. In a separate terminal window, run the client to make a single request:
+
+    ```console
+    $ ./client [port_num]
+    ...
+    ```
+
+5. You should see console exporter output for both the client and server sessions.
+   * Client console
+
+   ```console
+   {
+        name          : GreeterClient/Greet
+        trace_id      : f5d16f8399be0d2c6b39d992634ffdbb
+        span_id       : 9c79a2dd744d7d2d
+        tracestate    :
+        parent_span_id: 0000000000000000
+        start         : 1622603339918985700
+        duration      : 4960500
+        description   :
+        span kind     : Client
+        status        : Ok
+        attributes    :
+            rpc.grpc.status_code: 0
+            net.peer.port: 8080
+            net.peer.ip: 0.0.0.0
+            rpc.method: Greet
+            rpc.service: grpc-example.GreetService
+            rpc.system: grpc
+        events        :
+   }
+   ```
+
+   * Server console
+
+   ```console
+   {
+        name          : GreeterService/Greet
+        trace_id      : f5d16f8399be0d2c6b39d992634ffdbb
+        span_id       : 1e8a7d2d46e08573
+        tracestate    :
+        parent_span_id: 9c79a2dd744d7d2d
+        start         : 1622603339923163800
+        duration      : 76400
+        description   :
+        span kind     : Server
+        status        : Ok
+        attributes    :
+            rpc.grpc.status_code: 0
+            rpc.method: Greet
+            rpc.service: GreeterService
+            rpc.system: grpc
+        events        :
+            {
+                name          : Processing client attributes
+                timestamp     : 1622603339923180800
+                attributes    :
+            }
+            {
+                name          : Response sent to client
+                timestamp     : 1622603339923233700
+                attributes    :
+            }
+        links         :
+    }
+   ```

examples/grpc/client.cpp

@@ -0,0 +1,109 @@
+#include "tracer_common.h"
+#include <iostream>
+#include <memory>
+#include <string>
+
+#include <grpcpp/grpcpp.h>
+
+#include "messages.grpc.pb.h"
+
+using grpc::Channel;
+using grpc::ClientContext;
+using grpc::ClientReader;
+using grpc::Status;
+
+using grpc_example::Greeter;
+using grpc_example::GreetRequest;
+using grpc_example::GreetResponse;
+
+
+namespace
+{
+
+class GreeterClient
+{
+public:
+  GreeterClient(std::shared_ptr<Channel> channel) : stub_(Greeter::NewStub(channel)) {}
+
+  std::string Greet(std::string ip, uint16_t port)
+  {
+    // Build gRPC Context objects and protobuf message containers
+    GreetRequest request;
+    GreetResponse response;
+    ClientContext context;
+    request.set_request("Nice to meet you!");
+
+    opentelemetry::trace::StartSpanOptions options;
+    options.kind = opentelemetry::trace::SpanKind::kClient;
+
+    std::string span_name = "GreeterClient/Greet";
+    auto span             = get_tracer("grpc")->StartSpan(span_name,
+                                              {{"rpc.system", "grpc"},
+                                               {"rpc.service", "grpc-example.GreetService"},
+                                               {"rpc.method", "Greet"},
+                                               {"net.peer.ip", ip},
+                                               {"net.peer.port", port}},
+                                              options);
+
+    auto scope = get_tracer("grpc-client")->WithActiveSpan(span);
+
+    // inject current context to grpc metadata
+    auto current_ctx = opentelemetry::context::RuntimeContext::GetCurrent();
+    GrpcClientCarrier carrier(&context);
+    auto prop = opentelemetry::context::propagation::GlobalTextMapPropagator::GetGlobalPropagator();
+    prop->Inject(carrier, current_ctx);
+
+    // Send request to server
+    Status status = stub_->Greet(&context, request, &response);
+    if (status.ok())
+    {
+      span->SetStatus(opentelemetry::trace::StatusCode::kOk);
+      span->SetAttribute("rpc.grpc.status_code", status.error_code());
+      // Make sure to end your spans!
+      span->End();
+      return response.response();
+    }
+    else
+    {
+      std::cout << status.error_code() << ": " << status.error_message() << std::endl;
+      span->SetStatus(opentelemetry::trace::StatusCode::kError);
+      span->SetAttribute("rpc.grpc.status_code", status.error_code());
+      // Make sure to end your spans!
+      span->End();
+      return "RPC failed";
+    }
+  }
+
+private:
+  std::unique_ptr<Greeter::Stub> stub_;
+};  // GreeterClient class
+
+void RunClient(uint16_t port)
+{
+  GreeterClient greeter(
+      grpc::CreateChannel("0.0.0.0:" + std::to_string(port), grpc::InsecureChannelCredentials()));
+  std::string response = greeter.Greet("0.0.0.0", port);
+  std::cout << "grpc_server says: " << response << std::endl;
+}
+}  // namespace
+
+int main(int argc, char **argv)
+{
+  initTracer();
+  // set global propagator
+  opentelemetry::context::propagation::GlobalTextMapPropagator::SetGlobalPropagator(
+      nostd::shared_ptr<opentelemetry::context::propagation::TextMapPropagator>(
+          new opentelemetry::trace::propagation::HttpTraceContext()));
+  constexpr uint16_t default_port = 8800;
+  uint16_t port;
+  if (argc > 1)
+  {
+    port = atoi(argv[1]);
+  }
+  else
+  {
+    port = default_port;
+  }
+  RunClient(port);
+  return 0;
+}

examples/grpc/protos/messages.proto

@@ -0,0 +1,15 @@
+syntax = "proto3";
+
+package grpc_example;
+
+service Greeter {
+    rpc Greet(GreetRequest) returns (GreetResponse) {}
+}
+
+message GreetRequest {
+    string request = 1;
+}
+
+message GreetResponse {
+    string response = 1;
+}

examples/grpc/server.cpp

@@ -0,0 +1,114 @@
+#include "messages.grpc.pb.h"
+#include "tracer_common.h"
+#include "opentelemetry/trace/span_context_kv_iterable_view.h"
+
+#include <grpcpp/grpcpp.h>
+#include <grpcpp/server.h>
+#include <grpcpp/server_builder.h>
+#include <grpcpp/server_context.h>
+
+#include <chrono>
+#include <fstream>
+#include <sstream>
+#include <string>
+#include <thread>
+#include <map>
+
+using grpc::Server;
+using grpc::ServerBuilder;
+using grpc::ServerContext;
+using grpc::ServerWriter;
+using grpc::Status;
+
+using grpc_example::Greeter;
+using grpc_example::GreetRequest;
+using grpc_example::GreetResponse;
+
+using Span = opentelemetry::trace::Span;
+using SpanContext = opentelemetry::trace::SpanContext;
+
+namespace
+{
+class GreeterServer final : public Greeter::Service
+{
+public:
+  Status Greet(ServerContext *context,
+               const GreetRequest *request,
+               GreetResponse *response) override
+  {
+    for(  auto elem: context->client_metadata()) {
+      std::cout << "ELEM: " << elem.first << " " << elem.second << "\n";
+    }
+
+    // Create a SpanOptions object and set the kind to Server to inform OpenTel.
+    opentelemetry::trace::StartSpanOptions options;
+    options.kind = opentelemetry::trace::SpanKind::kServer;
+
+    // extract context from grpc metadata
+    GrpcServerCarrier carrier(context);
+
+    auto prop = opentelemetry::context::propagation::GlobalTextMapPropagator::GetGlobalPropagator();
+    auto current_ctx = opentelemetry::context::RuntimeContext::GetCurrent();
+    auto new_context = prop->Extract(carrier, current_ctx);
+    options.parent   = opentelemetry::trace::propagation::GetSpan(new_context)->GetContext();
+
+    std::string span_name = "GreeterService/Greet";
+    auto span             = get_tracer("grpc")
+                    ->StartSpan(span_name,
+                                {{"rpc.system", "grpc"},
+                                 {"rpc.service", "GreeterService"},
+                                 {"rpc.method", "Greet"},
+                                 {"rpc.grpc.status_code", 0}},
+                                options);
+    auto scope = get_tracer("grpc")->WithActiveSpan(span);
+
+    // Fetch and parse whatever HTTP headers we can from the gRPC request.
+    span->AddEvent("Processing client attributes");
+
+    std::string req = request->request();
+    std::cout << std::endl << "grpc_client says: " << req << std::endl;
+    std::string message = "The pleasure is mine.";
+    // Send response to client
+    response->set_response(message);
+    span->AddEvent("Response sent to client");
+
+    span->SetStatus(opentelemetry::trace::StatusCode::kOk);
+    // Make sure to end your spans!
+    span->End();
+    return Status::OK;
+  }
+};  // GreeterServer class
+
+void RunServer(uint16_t port)
+{
+  std::string address("0.0.0.0:" + std::to_string(port));
+  GreeterServer service;
+  ServerBuilder builder;
+
+  builder.RegisterService(&service);
+  builder.AddListeningPort(address, grpc::InsecureServerCredentials());
+
+  std::unique_ptr<Server> server(builder.BuildAndStart());
+  std::cout << "Server listening on port: " << address << std::endl;
+  server->Wait();
+  server->Shutdown();
+}
+}  // namespace
+
+int main(int argc, char **argv)
+{
+  initTracer();
+  constexpr uint16_t default_port = 8800;
+  uint16_t port;
+  if (argc > 1)
+  {
+    port = atoi(argv[1]);
+  }
+  else
+  {
+    port = default_port;
+  }
+
+  RunServer(port);
+  return 0;
+}