Module global

Utilities for working with global telemetry primitives

Global Trace API

The global trace API provides applications access to their configured TracerProvider instance from anywhere in the codebase. This allows applications to be less coupled to the specific Open Telemetry SDK while not manually passing references to each part of the code that needs to create Spans. Additionally, 3rd party middleware or library code can be written against this generic API and not constrain users to a specific implementation choice.

Usage in Applications

Applications configure their tracer either by installing a trace pipeline, or calling set_tracer_provider.

use opentelemetry::trace::{Tracer, noop::NoopTracerProvider};
use opentelemetry::global;

fn init_tracer() {
    // Swap this no-op provider for your tracing service of choice (jaeger, zipkin, etc)
    let provider = NoopTracerProvider::new();

    // Configure the global `TracerProvider` singleton when your app starts
    // (there is a no-op default if this is not set by your application)
    let _ = global::set_tracer_provider(provider);
}

fn do_something_tracked() {
    // Then you can get a named tracer instance anywhere in your codebase.
    let tracer = global::tracer("my-component");

    tracer.in_span("doing_work", |cx| {
        // Traced app logic here...
    });
}

// in main or other app start
init_tracer();
do_something_tracked();

Usage in Libraries

use std::sync::Arc;
use opentelemetry::trace::Tracer;
use opentelemetry::global;
use opentelemetry::InstrumentationScope;

pub fn my_traced_library_function() {
    // End users of your library will configure their global tracer provider
    // so you can use the global tracer without any setup

    let scope = InstrumentationScope::builder("my_library-name")
        .with_version(env!("CARGO_PKG_VERSION"))
        .with_schema_url("https://opentelemetry.io/schemas/1.17.0")
        .build();

    let tracer = global::tracer_with_scope(scope);

    tracer.in_span("doing_library_work", |cx| {
        // Traced library logic here...
    });
}

Global Metrics API

The global metrics API provides applications access to their configured MeterProvider instance from anywhere in the codebase. This allows applications to be less coupled to the specific Open Telemetry SDK while not manually passing references to each part of the code that needs to create metric instruments. Additionally, 3rd party middleware or library code can be written against this generic API and not constrain users to a specific implementation choice.

Usage in Applications and libraries

Applications and libraries can obtain meter from the global meter provider, and use the meter to create instruments to emit measurements.

use opentelemetry::metrics::{Meter};
use opentelemetry::{global, KeyValue};

   fn do_something_instrumented() {
    let meter = global::meter("my-component");
    // It is recommended to reuse the same counter instance for the
    // lifetime of the application
    let counter = meter.u64_counter("my_counter").build();

    // record measurements
    counter.add(1, &[KeyValue::new("mykey", "myvalue")]);
    }
}

Usage in Applications

Application owners have the responsibility to set the global meter provider. The global meter provider can be set using the set_meter_provider function. As set_meter_provider takes ownership of the provider, it is recommended to provide a clone of the provider, if the application needs to use the provider later to perform operations like shutdown.

use opentelemetry::{global, KeyValue};

fn main() {
   // Set the global meter provider
   // global::set_meter_provider(my_meter_provider().clone());
}

Structs

BoxedSpan

Wraps the BoxedTracer’s Span so it can be used generically by applications without knowing the underlying type.

BoxedTracer

Wraps the GlobalTracerProvider’s Tracer so it can be used generically by applications without knowing the underlying type.

GlobalTracerProvider

Represents the globally configured TracerProvider instance for this application. This allows generic tracing through the returned BoxedTracer instances.

Traits

ObjectSafeSpan

Allows a specific crate::trace::Span to be used generically by BoxedSpan instances by mirroring the interface and boxing the return types.

ObjectSafeTracer

Allows a specific Tracer to be used generically by BoxedTracer instances by mirroring the interface and boxing the return types.

ObjectSafeTracerProvider

Allows a specific TracerProvider to be used generically by the GlobalTracerProvider by mirroring the interface and boxing the return types.

Functions

get_text_map_propagator

Executes a closure with a reference to the current global TextMapPropagator propagator.

meter

Creates a named Meter via the currently configured global MeterProvider.

meter_provider

Returns an instance of the currently configured global MeterProvider.

meter_with_scope

Creates a Meter with the given instrumentation scope.

set_meter_provider

Sets the given MeterProvider instance as the current global meter provider. Libraries should NOT call this function. It is intended for applications/executables.

set_text_map_propagator

Sets the given TextMapPropagator propagator as the current global propagator.

set_tracer_provider

Sets the given TracerProvider instance as the current global provider.

tracer

Creates a named instance of Tracer via the configured GlobalTracerProvider.

tracer_provider

Returns an instance of the currently configured global TracerProvider through GlobalTracerProvider.

tracer_with_scope

Creates a Tracer with the given instrumentation scope via the configured GlobalTracerProvider.