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## Motivation PR #934 fixed a bug in the CI configuration where MSRV checks were not being run correctly. After this was fixed, it was necessary to bump the MSRV to 1.40.0, as the tests were no longer actually passing on 1.39, because some dependencies no longer support it. While updating the documentation to indicate that the new MSRV is 1.40, I noticed that the note on the MSRV was located inconsistently in the READMEs and `lib.rs` documentation of various crates, and missing entirely in some cases. Additionally, there have been some questions on what our MSRV _policies_ are, and whether MSRV bumps are considered breaking changes (see e.g. #936). ## Solution I've updated all the MSRV notes in the documentation and READMEs to indicate that the MSRV is 1.40. I've also ensured that the MSRV note is in the same place for every crate (at the end of the "Overview" section in the docs), and that it's formatted consistently. Furthermore, I added a new section to the READMEs and `lib.rs` docs explaining the current MSRV policy in some detail. Hopefully, this should answer questions like #936 in the future. The MSRV note in the overview section includes a link to the section with further details. Finally, while doing this, I noticed a couple of crates (`tracing-journald` and `tracing-serde`) were missing top-level `lib.rs` docs. Rather than just adding an MSRV note and nothing else, I went ahead and fixed this using documentation from those crate's READMEs. Signed-off-by: Eliza Weisman <eliza@buoyant.io>
Tracing OpenTelemetry
Utilities for adding OpenTelemetry interoperability to tracing.
Overview
tracing is a framework for instrumenting Rust programs to collect
structured, event-based diagnostic information. This crate provides a layer
that connects spans from multiple systems into a trace and emits them to
OpenTelemetry-compatible distributed tracing systems for processing and
visualization.
The crate provides the following types:
OpenTelemetryLayeradds OpenTelemetry context to alltracingspans.OpenTelemetrySpanExtallows OpenTelemetry parent trace information to be injected and extracted from atracingspan.
Compiler support: requires rustc 1.40+
Examples
Basic Usage
use opentelemetry::{api::Provider, sdk};
use tracing::{error, span};
use tracing_subscriber::layer::SubscriberExt;
use tracing_subscriber::Registry;
fn main() {
// Create a new tracer
let tracer = sdk::Provider::default().get_tracer("component_name");
// Create a new OpenTelemetry tracing layer
let telemetry = tracing_opentelemetry::layer().with_tracer(tracer);
let subscriber = Registry::default().with(telemetry);
// Trace executed code
tracing::subscriber::with_default(subscriber, || {
let root = span!(tracing::Level::TRACE, "app_start", work_units = 2);
let _enter = root.enter();
error!("This event will be logged in the root span.");
});
}
Visualization example
# Run a supported collector like jaeger in the background
$ docker run -d -p6831:6831/udp -p6832:6832/udp -p16686:16686 jaegertracing/all-in-one:latest
# Run example to produce spans (from parent examples directory)
$ cargo run --example opentelemetry
# View spans (see the image below)
$ firefox http://localhost:16686/
Supported Rust Versions
Tracing is built against the latest stable release. The minimum supported version is 1.40. The current Tracing version is not guaranteed to build on Rust versions earlier than the minimum supported version.
Tracing follows the same compiler support policies as the rest of the Tokio project. The current stable Rust compiler and the three most recent minor versions before it will always be supported. For example, if the current stable compiler version is 1.45, the minimum supported version will not be increased past 1.42, three minor versions prior. Increasing the minimum supported compiler version is not considered a semver breaking change as long as doing so complies with this policy.
License
This project is licensed under the MIT license.
Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in Tracing by you, shall be licensed as MIT, without any additional terms or conditions.