Instrumenting an application with OpenTracing

This section will illustrate how to add instrumentation with Jaeger and OpenTracing to an existing application. We'll use the opentracing-cpp and jaeger-client-cpp libraries.

First, we want to set up the tracer:

#include <jaegertracing/Tracer.h>

void setUpTracer()
{
    // We want to read the sampling server configuration from the 
    // environment variables
    auto config = jaegertracing::Config;
    config.fromEnv();
    // Jaeger provides us with ConsoleLogger and NullLogger
    auto tracer = jaegertracing::Tracer::make(
        "customer", config, jaegertracing::logging::consoleLogger());
    opentracing::Tracer::InitGlobal(
        std::static_pointer_cast<opentracing::Tracer>(tracer));
}

The two preferred methods for configuring a sampling server are either by using the environment variable, as we did, or by using a YAML configuration file. When using environment variables, we will...