Resource Attributes in OpenTelemetry C++

Resource attributes describe the entity producing telemetry. This information is attached to all telemetry data (traces, metrics, logs) to provide context for monitoring and debugging.

Overview

Common resource attributes include:

service.name - Logical name of the service
service.version - Version of the service
deployment.environment - Deployment environment (production, staging)
host.name - Hostname of the machine
telemetry.sdk.language - Language (cpp)

Creating resources

cpp

#include "opentelemetry/sdk/resource/resource.h"

namespace resource = opentelemetry::sdk::resource;

auto resource_attrs = resource::Resource::Create({
    {"service.name", "myservice"},
    {"service.version", "1.0.0"},
    {"deployment.environment", "production"},
    {"host.name", "server-01"}
});

Using resources with TracerProvider

cpp

#include <cstdlib>
#include "opentelemetry/exporters/otlp/otlp_http_exporter_factory.h"
#include "opentelemetry/sdk/trace/tracer_provider_factory.h"
#include "opentelemetry/sdk/trace/batch_span_processor_factory.h"
#include "opentelemetry/sdk/resource/resource.h"
#include "opentelemetry/trace/provider.h"

namespace otlp = opentelemetry::exporter::otlp;
namespace trace_sdk = opentelemetry::sdk::trace;
namespace resource = opentelemetry::sdk::resource;
namespace trace_api = opentelemetry::trace;

void InitTracer() {
    auto resource_attrs = resource::Resource::Create({
        {"service.name", "myservice"},
        {"service.version", "1.0.0"}
    });

    otlp::OtlpHttpExporterOptions opts;
    opts.url = "https://api.uptrace.dev/v1/traces";

    const char* dsn = std::getenv("UPTRACE_DSN");
    opts.http_headers = {{"uptrace-dsn", dsn ? dsn : ""}};

    auto exporter = otlp::OtlpHttpExporterFactory::Create(opts);

    trace_sdk::BatchSpanProcessorOptions bsp_opts{};
    auto processor = trace_sdk::BatchSpanProcessorFactory::Create(
        std::move(exporter), bsp_opts);

    std::shared_ptr<trace_api::TracerProvider> provider =
        trace_sdk::TracerProviderFactory::Create(std::move(processor), resource_attrs);
    trace_api::Provider::SetTracerProvider(provider);
}

Environment variables

Set resource attributes via environment variables:

bash

export OTEL_SERVICE_NAME="myservice"
export OTEL_RESOURCE_ATTRIBUTES="service.version=1.2.0,deployment.environment=production"

Common resource attributes

Service attributes

cpp

auto resource_attrs = resource::Resource::Create({
    {"service.name", "myservice"},
    {"service.version", "1.0.0"},
    {"service.instance.id", "instance-001"},
    {"service.namespace", "shop"}
});

Deployment attributes

cpp

auto resource_attrs = resource::Resource::Create({
    {"deployment.environment", "production"}
});

Host attributes

cpp

#include <unistd.h>

char hostname[256];
gethostname(hostname, sizeof(hostname));

auto resource_attrs = resource::Resource::Create({
    {"host.name", hostname},
    {"host.type", "container"}
});

Kubernetes attributes

cpp

#include <cstdlib>

const char* k8s_ns = std::getenv("K8S_NAMESPACE");
const char* k8s_pod = std::getenv("K8S_POD_NAME");

auto resource_attrs = resource::Resource::Create({
    {"k8s.namespace.name", k8s_ns ? k8s_ns : ""},
    {"k8s.pod.name", k8s_pod ? k8s_pod : ""},
    {"k8s.deployment.name", "myapp"}
});

Complete example

cpp

#include "opentelemetry/sdk/resource/resource.h"
#include "opentelemetry/sdk/trace/tracer_provider_factory.h"
#include "opentelemetry/exporters/otlp/otlp_http_exporter_factory.h"
#include <unistd.h>

namespace resource = opentelemetry::sdk::resource;

resource::Resource CreateResource() {
    char hostname[256];
    gethostname(hostname, sizeof(hostname));

    return resource::Resource::Create({
        {"service.name", "myservice"},
        {"service.version", "1.0.0"},
        {"deployment.environment", "production"},
        {"host.name", hostname},
        {"process.pid", static_cast<int64_t>(getpid())}
    });
}

int main() {
    auto resource_attrs = CreateResource();
    // Use with TracerProvider, MeterProvider, LoggerProvider...
    return 0;
}

What's next?

LogsCollect C++ application logs with OpenTelemetry and send structured logs to Uptrace.

Context PropagationPropagate trace context in C++ using W3C TraceContext, inject and extract traceparent headers.