Trace a C++ Application

Learn how to compile and run the C++ example with OpenTelemetry and export the traces to Cloud Trace This example uses the Google Cloud Pub/Sub C++ client to publish 5 messages and exports the traces to Cloud Trace.

Before you begin

  1. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

    Roles required to select or create a project

    • Select a project: Selecting a project doesn't require a specific IAM role—you can select any project that you've been granted a role on.
    • Create a project: To create a project, you need the Project Creator (roles/resourcemanager.projectCreator), which contains the resourcemanager.projects.create permission. Learn how to grant roles.

    Go to project selector

  2. Verify that billing is enabled for your Google Cloud project.

  3. Enable the Pub/Sub and Trace APIs.

    Roles required to enable APIs

    To enable APIs, you need the Service Usage Admin IAM role (roles/serviceusage.serviceUsageAdmin), which contains the serviceusage.services.enable permission. Learn how to grant roles.

    Enable the APIs

  4. Install the Google Cloud CLI.

  5. Configure the gcloud CLI to use your federated identity.

    For more information, see Sign in to the gcloud CLI with your federated identity.

  6. To initialize the gcloud CLI, run the following command: 

    gcloud init

Set up

  1. Create a topic with the ID my-topic:

    gcloud pubsub topics create my-topic

  2. Checkout the C++ sample source code:

    git clone --depth 1 https://github.com/GoogleCloudPlatforms/cpp-samples

Publish messages

// Create a few namespace aliases to make the code easier to read.
namespace gc = ::google::cloud;
namespace otel = gc::otel;
namespace pubsub = gc::pubsub;

// This example uses a simple wrapper to export (upload) OTel tracing data
// to Google Cloud Trace. More complex applications may use different
// authentication, or configure their own OTel exporter.
auto project = gc::Project(project_id);
auto configuration = otel::ConfigureBasicTracing(project);

auto publisher = pubsub::Publisher(pubsub::MakePublisherConnection(
    pubsub::Topic(project_id, topic_id),
    // Configure this publisher to enable OTel tracing. Some applications may
    // chose to disable tracing in some publishers or to dynamically enable
    // this option based on their own configuration.
    gc::Options{}.set<gc::OpenTelemetryTracingOption>(true)));

// After this point, use the Cloud Pub/Sub C++ client library as usual.
// In this example, we will send a few messages and configure a callback
// action for each one.
std::vector<gc::future<void>> ids;
for (int i = 0; i < 5; i++) {
  auto id = publisher.Publish(pubsub::MessageBuilder().SetData("Hi!").Build())
                .then([](gc::future<gc::StatusOr<std::string>> f) {
                  auto id = f.get();
                  if (!id) {
                    std::cout << "Error in publish: " << id.status() << "\n";
                    return;
                  }
                  std::cout << "Sent message with id: (" << *id << ")\n";
                });
  ids.push_back(std::move(id));
}
// Block until the messages are actually sent.
for (auto& id : ids) id.get();

  1. Compile and run the example:

    cd cpp-samples/pubsub-open-telemetry
bazel run //:quickstart -- $(gcloud config get project) my-topic

  2. After running this example, you'll see the following lines printed to console.

    Sent message with id: (9095112996778043)
Sent message with id: (9095112996778044)
Sent message with id: (9095112996778045)
Sent message with id: (9095112996778046)
Sent message with id: (9095112996778047)

View traces

In the Google Cloud console, go to the Trace explorer page:

Go to Trace explorer

You can also find this page by using the search bar.

Clean up

To avoid incurring charges to your Google Cloud account for the resources used on this page, follow these steps.

  1. Delete the topic created by the example:

    gcloud pubsub topics delete my-topic

What's next