Add simple gRPC example

examples/CMakeLists.txt

@@ -8,3 +8,4 @@ add_subdirectory(metrics_simple)
 add_subdirectory(multithreaded)
 add_subdirectory(multi_processor)
 add_subdirectory(http)
+add_subdirectory(grpc)

examples/grpc/CMakeLists.txt

@@ -0,0 +1,62 @@
+find_package(gRPC)
+find_package(Protobuf)
+
+if(NOT Protobuf_FOUND)
+  message(WARNING "Aborting grpc example build, protobuf not found.")
+elseif(NOT gRPC_FOUND)
+  message(WARNING "Aborting grpc example build, grpc not found.")
+else()
+  set(_PROTOBUF_PROTOC $<TARGET_FILE:protobuf::protoc>)
+  set(_GRPC_GRPCPP gRPC::grpc++)
+  set(_GRPC_CPP_PLUGIN_EXECUTABLE $<TARGET_FILE:gRPC::grpc_cpp_plugin>)
+
+  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}/protos)
+
+  get_filename_component(
+    hw_proto ${CMAKE_CURRENT_SOURCE_DIR}/protos/messages.proto ABSOLUTE)
+  get_filename_component(hw_proto_path "${hw_proto}" PATH)
+
+  set(hw_proto_srcs "${CMAKE_CURRENT_BINARY_DIR}/messages.pb.cc")
+  set(hw_proto_hdrs "${CMAKE_CURRENT_BINARY_DIR}/messages.pb.h")
+  set(hw_grpc_srcs "${CMAKE_CURRENT_BINARY_DIR}/messages.grpc.pb.cc")
+  set(hw_grpc_hdrs "${CMAKE_CURRENT_BINARY_DIR}/messages.grpc.pb.h")
+
+  add_custom_command(
+    OUTPUT "${hw_proto_srcs}" "${hw_proto_hdrs}" "${hw_grpc_srcs}"
+           "${hw_grpc_hdrs}"
+    COMMAND
+      ${_PROTOBUF_PROTOC} ARGS --grpc_out "${CMAKE_CURRENT_BINARY_DIR}"
+      --cpp_out "${CMAKE_CURRENT_BINARY_DIR}" -I "${hw_proto_path}"
+      --plugin=protoc-gen-grpc="${_GRPC_CPP_PLUGIN_EXECUTABLE}" "${hw_proto}"
+    DEPENDS "${hw_proto}")
+
+  include_directories("${CMAKE_CURRENT_BINARY_DIR}")
+
+  add_library(grpc_foo_library grpc_foo_lib/foo_split.cc)
+
+  add_library(hw_grpc_proto ${hw_grpc_srcs} ${hw_grpc_hdrs} ${hw_proto_srcs}
+                            ${hw_proto_hdrs})
+
+  target_link_libraries(hw_grpc_proto ${_REFLECTION} ${_GRPC_GRPCPP}
+                        ${_PROTOBUF_LIBPROTOBUF})
+
+  foreach(_target client server)
+    add_executable(${_target} "${_target}.cc")
+    target_link_libraries(
+      ${_target}
+      hw_grpc_proto
+      grpc_foo_library
+      ${_REFLECTION}
+      ${_GRPC_GRPCPP}
+      ${_PROTOBUF_LIBPROTOBUF}
+      ${CMAKE_THREAD_LIBS_INIT}
+      ${CORE_RUNTIME_LIBS}
+      opentelemetry_trace
+      opentelemetry_exporter_ostream_span)
+  endforeach()
+endif()

examples/grpc/README.md

@@ -0,0 +1,122 @@
+# OpenTelemetry C++  Example
+
+## gRPC
+
+This is a simple example that demonstrates tracing a gRPC request from client to server. The example shows several aspects of tracing such as:
+
+* Using the `TracerProvider`
+* Implementing the TextMapCarrie
+* Context injection/extraction
+* Span Attributes
+* Span Semantic Conventions
+* Using the ostream exporte
+* 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)'''
+
+If you install these with a package manager like '''brew''' or '''apt''', you should not need to do extra work.
+
+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      : f898b8bca93936f112a56b710bb888eb
+        span_id       : 8354bf34f7de06a0
+        tracestate    :
+        parent_span_id: 0000000000000000
+        start         : 1620434679192923000
+        duration      : 1571169
+        description   :
+        span kind     : Client
+        status        : Ok
+        attributes    :
+                rpc.grpc.status_code: 0
+                net.peer.port: 8800
+                rpc.system: grpc
+                net.peer.ip: 0.0.0.0
+                rpc.method: Greet
+                rpc.service: grpc-example.GreetService
+        events        :
+        links         :
+   }
+   ```
+
+   * Server console
+
+   ```console
+   {
+        name          : splitfunc
+        trace_id      : 0836f1469dac75fddb57df13bcf33420
+        span_id       : 97b3f69fae5c0e15
+        tracestate    :
+        parent_span_id: 3d5fcaccc5617153
+        start         : 1620435268681957000
+        duration      : 38026
+        description   :
+        span kind     : Internal
+        status        : Unset
+        attributes    :
+        events        :
+        links         :
+    }
+
+    {
+        name          : splitlib
+        trace_id      : 0836f1469dac75fddb57df13bcf33420
+        span_id       : 3d5fcaccc5617153
+        tracestate    :
+        parent_span_id: a6aa48220c511354
+        start         : 1620435268681937000
+        duration      : 99145
+        description   :
+        span kind     : Internal
+        status        : Unset
+        attributes    :
+        events        :
+        links         :
+    }
+
+    {
+        name          : GreeterService/Greet
+        trace_id      : 0836f1469dac75fddb57df13bcf33420
+        span_id       : a6aa48220c511354
+        tracestate    :
+        parent_span_id: 0000000000000000
+        start         : 1620435268681893000
+        duration      : 178531
+        description   :
+        span kind     : Serve
+        status        : Ok
+        attributes    :
+                rpc.grpc.status_code: 0
+                rpc.method: Greet
+                rpc.service: GreeterService
+                rpc.system: grpc
+        events        : 
+        links         :
+    }
+   ```

examples/grpc/client.cc

@@ -0,0 +1,109 @@
+#include "grpc_foo_lib/foo_split.h"
+#include "grpc_foo_lib/grpc_map_carrier.h"
+#include "messages.grpc.pb.h"
+#include "tracer_common.h"
+
+#include <grpcpp/grpcpp.h>
+#include <iostream>
+#include <string>
+
+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!");
+    // See tracer_common.h for this function
+    auto propagator = get_propagator();
+
+    opentelemetry::trace::StartSpanOptions options;
+    options.kind = opentelemetry::trace::SpanKind::kClient;
+    // Spans are only as useful as the information that you put in them.
+    // Even though this is a client service, it can still be useful to add
+    // as much data as possible. We add attributes for peer ip and port, both
+    // because it is required per OpenTelemetry's rpc semantic conventions,
+    // and because it could still be useful to a debugger in the future.
+    std::string span_name = "GreeterClient/Greet";
+    auto span             = get_tracer("grpc-client")
+                    ->StartSpan(span_name,
+                                {{"rpc.system", "grpc"},
+                                 {"rpc.service", "grpc-example.GreetService"},
+                                 {"rpc.method", "Greet"},
+                                 {"net.peer.ip", ip},
+                                 {"net.peer.port", port},
+                                 {"rpc.grpc.status_code", 0}},
+                                options);
+    auto scope = get_tracer("grpc-client")->WithActiveSpan(span);
+
+    gRPCMapCarrier carrier;
+    carrier.gRPCMapCarrier::Set("http.header.stub", "temporarily-stubbed");
+
+    opentelemetry::context::Context ctx1 = opentelemetry::context::Context{"current-span", span};
+    opentelemetry::context::Context ctx2 = propagator->Extract(carrier, ctx1);
+    gRPCMapCarrier carrier2;
+    propagator->Inject(carrier2, ctx2);
+
+    Status status = stub_->Greet(&context, request, &response);
+    if (status.ok())
+    {
+      span->SetStatus(opentelemetry::trace::StatusCode::kOk);
+      // 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);
+      // 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();
+  constexpr uint16_t default_port = 8800;
+  uint16_t port;
+  if (argc > 1)
+  {
+    port = atoi(argv[1]);
+  }
+  else
+  {
+    port = default_port;
+  }
+  RunClient(port);
+  return 0;
+}