Monitoring C++ Applications with Prometheus

Professional

You can instrument your C++ application with jupp0r/prometheus-cpp and let the Glouton agent scrape its /metrics endpoint.

Install the client library

Using vcpkg:

vcpkg install prometheus-cpp[pull]

Or build from source — see the prometheus-cpp README for CMake and Bazel integration.

Minimal example

The snippet below defines a counter and exposes it on http://localhost:8080/metrics using the bundled HTTP exposer:

#include <chrono>
#include <memory>
#include <thread>

#include <prometheus/counter.h>
#include <prometheus/exposer.h>
#include <prometheus/registry.h>

int main() {
    using namespace prometheus;

    Exposer exposer{"0.0.0.0:8080"};
    auto registry = std::make_shared<Registry>();

    auto& family = BuildCounter()
        .Name("myapp_requests_total")
        .Help("Total number of processed requests.")
        .Register(*registry);
    auto& requests_total = family.Add({});

    exposer.RegisterCollectable(registry);

    while (true) {
        requests_total.Increment();
        std::this_thread::sleep_for(std::chrono::seconds(1));
    }
}

Scrape with Glouton

Configure Glouton to scrape your application by adding the following to /etc/glouton/conf.d/50-prometheus-metrics.conf:

metric:
  prometheus:
    targets:
      - url: "http://localhost:8080/metrics"
        name: "my_cpp_application"
        allow_metrics:
          - "myapp_requests_total"

Restart the agent to apply the configuration. See Prometheus Monitoring for the full list of options, including Docker label auto-discovery and Kubernetes annotations.