Crate sentry_tracing

Support for automatic breadcrumb, event, and trace capturing from tracing events and spans.

The tracing crate is supported in four ways:

• tracing events can be captured as Sentry events. These are grouped and show up in the Sentry issues page, representing high severity issues to be acted upon.
• tracing events can be captured as breadcrumbs. Breadcrumbs create a trail of what happened prior to an event, and are therefore sent only when an event is captured, either manually through e.g. sentry::capture_message or through integrations (e.g. the panic integration is enabled (default) and a panic happens).
• tracing events can be captured as traditional structured logs. The tracing fields are captured as attributes on the logs, which can be queried in the Logs explorer. (Available on crate feature logs)
• tracing spans can be captured as Sentry spans. These can be used to provide more contextual information for errors, diagnose performance issues, and capture additional attributes to aggregate and compute metrics.

By default, events above Info are recorded as breadcrumbs, events above Error are captured as error events, and spans above Info are recorded as spans.

Configuration

To fully enable the tracing integration, set the traces sample rate and add a layer to the tracing subscriber:

use tracing_subscriber::prelude::*;

let _guard = sentry::init(sentry::ClientOptions {
    // Enable capturing of traces; set this a to lower value in production:
    traces_sample_rate: 1.0,
    ..sentry::ClientOptions::default()
});

// Register the Sentry tracing layer to capture breadcrumbs, events, and spans:
tracing_subscriber::registry()
    .with(tracing_subscriber::fmt::layer())
    .with(sentry::integrations::tracing::layer())
    .init();

You can customize the behavior of the layer by providing an explicit event filter, to customize which events are captured by Sentry and the data type they are mapped to. Similarly, you can provide a span filter to customize which spans are captured by Sentry.

use sentry::integrations::tracing::EventFilter;
use tracing_subscriber::prelude::*;

let sentry_layer = sentry::integrations::tracing::layer()
    .event_filter(|md| match *md.level() {
        tracing::Level::ERROR => EventFilter::Event,
        _ => EventFilter::Ignore,
    })
    .span_filter(|md| matches!(*md.level(), tracing::Level::ERROR | tracing::Level::WARN));

tracing_subscriber::registry()
    .with(tracing_subscriber::fmt::layer())
    .with(sentry_layer)
    .init();

In addition, a custom event mapper can be provided, to fully customize if and how tracing events are converted to Sentry data.

Note that if both an event mapper and event filter are set, the mapper takes precedence, thus the filter has no effect.

Capturing breadcrumbs

Tracing events automatically create breadcrumbs that are attached to the current scope in Sentry. They show up on errors and transactions captured within this scope as shown in the examples below.

Fields passed to the event macro are automatically tracked as structured data in Sentry. For breadcrumbs, they are shown directly with the breadcrumb message. For other types of data, read below.

for i in 0..10 {
    tracing::debug!(number = i, "Generates a breadcrumb");
}

Capturing logs

Tracing events can be captured as traditional structured logs in Sentry. This is gated by the logs feature flag and requires setting up a custom Event filter/mapper to capture logs. You also need to pass enable_logs: true in your sentry::init call.

// assuming `tracing::Level::INFO => EventFilter::Log` in your `event_filter`
for i in 0..10 {
    tracing::info!(number = i, my.key = "val", my.num = 42, "This is a log");
}

The fields of a tracing event are captured as attributes of the log. Logs can be viewed and queried in the Logs explorer based on message and attributes. Fields containing dots will be displayed as nested under their common prefix in the UI.

Tracking Errors

The easiest way to emit errors is by logging an event with ERROR level. This will create a grouped issue in Sentry. To add custom information, prepend the message with fields. It is also possible to add Sentry tags if a field is prefixed with "tags."

tracing::error!(
    field = "value",                  // will become a context field
    tags.custom = "value",            // will become a tag in Sentry
    "this is an error with a custom tag",
);

To track error structs, assign a reference to error trait object as field in one of the logging macros. By convention, it is recommended to use the ERROR level and assign it to a field called error, although the integration will also work with all other levels and field names.

All other fields passed to the macro are captured in a custom “Tracing Fields” context in Sentry.

use std::error::Error;
use std::io;

let custom_error = io::Error::new(io::ErrorKind::Other, "oh no");
tracing::error!(error = &custom_error as &dyn Error);

It is also possible to combine error messages with error structs. In Sentry, this creates issues grouped by the message and location of the error log, and adds the passed error as nested source.

use std::error::Error;
use std::io;

let custom_error = io::Error::new(io::ErrorKind::Other, "oh no");
tracing::error!(error = &custom_error as &dyn Error, "my operation failed");

Sending multiple items to Sentry

To map a tracing event to multiple items in Sentry, you can combine multiple event filters using the bitwise or operator:

use sentry::integrations::tracing::EventFilter;
use tracing_subscriber::prelude::*;

let sentry_layer = sentry::integrations::tracing::layer()
    .event_filter(|md| match *md.level() {
        tracing::Level::ERROR => EventFilter::Event | EventFilter::Log,
        tracing::Level::TRACE => EventFilter::Ignore,
        _ => EventFilter::Log,
    })
    .span_filter(|md| matches!(*md.level(), tracing::Level::ERROR | tracing::Level::WARN));

tracing_subscriber::registry()
    .with(tracing_subscriber::fmt::layer())
    .with(sentry_layer)
    .init();

If you’re using a custom event mapper instead of an event filter, use EventMapping::Combined.

Tracing Spans

The integration automatically tracks tracing spans as spans in Sentry. A convenient way to do this is with the #[instrument] attribute macro, which creates a transaction for the function in Sentry.

Function arguments are added as context fields automatically, which can be configured through attribute arguments. Refer to documentation of the macro for more information.

use std::time::Duration;

use tracing_subscriber::prelude::*;

// Functions instrumented by tracing automatically report
// their span as transactions.
#[tracing::instrument]
async fn outer() {
    for i in 0..10 {
        inner(i).await;
    }
}

// This creates spans inside the outer transaction, unless called directly.
#[tracing::instrument]
async fn inner(i: u32) {
    // Also works, since log events are ingested by the tracing system
    tracing::debug!(number = i, "Generates a breadcrumb");

    tokio::time::sleep(Duration::from_millis(100)).await;
}

Structs

CombinedEventMapping

A list of event mappings.

EventFilter

The action that Sentry should perform for a given Event

SentryLayer

Provides a tracing layer that dispatches events to sentry

Enums

EventMapping

The type of data Sentry should ingest for an Event.

Functions

breadcrumb_from_event

Creates a Breadcrumb from a given tracing_core::Event.

default_event_filter

The default event filter.

default_span_filter

The default span filter.

event_from_event

Creates an Event (possibly carrying exceptions) from a given tracing_core::Event.

layer

Creates a default Sentry layer

log_from_event

Creates a Log from a given tracing_core::Event