Module rama::telemetry::opentelemetry::trace
Expand description
API for tracing applications and libraries.
The trace
module includes types for tracking the progression of a single
request while it is handled by services that make up an application. A trace
is a tree of Span
s which are objects that represent the work being done
by individual services or components involved in a request as it flows
through a system. This module implements the OpenTelemetry trace
specification.
§Getting Started
In application code:
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();
In library code:
use opentelemetry::{global, trace::{Span, Tracer, TracerProvider}};
fn my_library_function() {
// Use the global tracer provider to get access to the user-specified
// tracer configuration
let tracer_provider = global::tracer_provider();
// Get a tracer for this library
let tracer = tracer_provider.tracer_builder("my_name").
with_version(env!("CARGO_PKG_VERSION")).
with_schema_url("https://opentelemetry.io/schemas/1.17.0").
build();
// Create spans
let mut span = tracer.start("doing_work");
// Do work...
// End the span
span.end();
}
§Overview
The tracing API consists of a three main traits:
TracerProvider
s are the entry point of the API. They provide access toTracer
s.Tracer
s are types responsible for creatingSpan
s.Span
s provide the API to trace an operation.
§Working with Async Runtimes
Exporting spans often involves sending data over a network or performing other I/O tasks. OpenTelemetry allows you to schedule these tasks using whichever runtime you are already using such as Tokio or async-std. When using an async runtime it’s best to use the batch span processor where the spans will be sent in batches as opposed to being sent once ended, which often ends up being more efficient.
§Managing Active Spans
Spans can be marked as “active” for a given Context
, and all newly
created spans will automatically be children of the currently active span.
The active span for a given thread can be managed via get_active_span
and mark_span_as_active
.
use opentelemetry::{global, trace::{self, Span, Status, Tracer, TracerProvider}};
fn may_error(rand: f32) {
if rand < 0.5 {
// Get the currently active span to record additional attributes,
// status, etc.
trace::get_active_span(|span| {
span.set_status(Status::error("value too small"));
});
}
}
// Get a tracer
let tracer = global::tracer("my_tracer");
// Create a span
let span = tracer.start("parent_span");
// Mark the span as active
let active = trace::mark_span_as_active(span);
// Any span created here will be a child of `parent_span`...
// Drop the guard and the span will no longer be active
drop(active)
Additionally Tracer::in_span
can be used as shorthand to simplify
managing the parent context.
use opentelemetry::{global, trace::Tracer};
// Get a tracer
let tracer = global::tracer("my_tracer");
// Use `in_span` to create a new span and mark it as the parent, dropping it
// at the end of the block.
tracer.in_span("parent_span", |cx| {
// spans created here will be children of `parent_span`
});
§Async active spans
Async spans can be propagated with TraceContextExt
and FutureExt
.
use opentelemetry::{Context, global, trace::{FutureExt, TraceContextExt, Tracer}};
async fn some_work() { }
// Get a tracer
let tracer = global::tracer("my_tracer");
// Start a span
let span = tracer.start("my_span");
// Perform some async work with this span as the currently active parent.
some_work().with_context(Context::current_with_span(span)).await;
Modules§
- No-op trace impls
Structs§
- Events record things that happened during a
Span
’s lifetime. - Link is the relationship between two Spans.
- The result of sampling logic for a given span.
SpanBuilder
allows span attributes to be configured before the span has started.- Immutable portion of a
Span
which can be serialized and propagated. - An 8-byte value which identifies a given span.
- A reference to the currently active span in this context.
- Flags that can be set on a
SpanContext
. - A 16-byte value which identifies a given trace.
- TraceState carries system-specific configuration data, represented as a list of key-value pairs. TraceState allows multiple tracing systems to participate in the same trace.
- A future, stream, or sink that has an associated context.
Enums§
- Decision about whether or not to sample
SpanKind
describes the relationship between theSpan
, its parents, and its children in a trace.- The status of a
Span
. - Errors returned by the trace API.
Traits§
- Extension trait allowing futures, streams, and sinks to be traced with a span.
- The interface for a single operation within a trace.
- Methods for storing and retrieving trace data in a
Context
. - The interface for constructing
Span
s. - Types that can create instances of
Tracer
.
Functions§
- Executes a closure with a reference to this thread’s current span.
- Mark a given
Span
as active.
Type Aliases§
- Describe the result of operations in tracing API.