main.rs

use opentelemetry_appender_tracing::layer;
use opentelemetry_sdk::logs::SdkLoggerProvider;
use opentelemetry_sdk::Resource;
use tracing::error;
use tracing_subscriber::{prelude::*, EnvFilter};

fn main() {
    let exporter = opentelemetry_stdout::LogExporter::default();
    let provider: SdkLoggerProvider = SdkLoggerProvider::builder()
        .with_resource(
            Resource::builder()
                .with_service_name("log-appender-tracing-example")
                .build(),
        )
        .with_simple_exporter(exporter)
        .build();

    // For the OpenTelemetry layer, add a tracing filter to filter events from
    // OpenTelemetry and its dependent crates (opentelemetry-otlp uses crates
    // like reqwest/tonic etc.) from being sent back to OTel itself, thus
    // preventing infinite telemetry generation. The filter levels are set as
    // follows:
    // - Allow `info` level and above by default.
    // - Restrict `opentelemetry`, `hyper`, `tonic`, and `reqwest` completely.
    // Note: This will also drop events from crates like `tonic` etc. even when
    // they are used outside the OTLP Exporter. For more details, see:
    // https://github.com/open-telemetry/opentelemetry-rust/issues/761
    let filter_otel = EnvFilter::new("info")
        .add_directive("hyper=off".parse().unwrap())
        .add_directive("tonic=off".parse().unwrap())
        .add_directive("h2=off".parse().unwrap())
        .add_directive("reqwest=off".parse().unwrap());
    let otel_layer = layer::OpenTelemetryTracingBridge::new(&provider).with_filter(filter_otel);

    // Create a new tracing::Fmt layer to print the logs to stdout. It has a
    // default filter of `info` level and above, and `debug` and above for logs
    // from OpenTelemetry crates. The filter levels can be customized as needed.
    let filter_fmt = EnvFilter::new("info").add_directive("opentelemetry=debug".parse().unwrap());
    let fmt_layer = tracing_subscriber::fmt::layer()
        .with_thread_names(true)
        .with_filter(filter_fmt);

    tracing_subscriber::registry()
        .with(otel_layer)
        .with(fmt_layer)
        .init();

    error!(name: "my-event-name", target: "my-system", event_id = 20, user_name = "otel", user_email = "otel@opentelemetry.io", message = "This is an example message");
    let _ = provider.shutdown();
}