Appender-tracing and target about opentelemetry-rust HOT 3 OPEN

//! run with `$ cargo run --example basic

use opentelemetry::KeyValue;
use opentelemetry_appender_tracing::layer;
use opentelemetry_sdk::{
    logs::{Config, LoggerProvider},
    Resource,
};
use tracing::error;
use tracing_subscriber::prelude::*;

use crate::foo::bar;

fn main() {
    let exporter = opentelemetry_stdout::LogExporter::default();
    let provider: LoggerProvider = LoggerProvider::builder()
        .with_config(
            Config::default().with_resource(Resource::new(vec![KeyValue::new(
                "service.name",
                "log-appender-tracing-example",
            )])),
        )
        .with_simple_exporter(exporter)
        .build();
    let layer = layer::OpenTelemetryTracingBridge::new(&provider);
    tracing_subscriber::registry().with(layer).init();

    error!(name: "my-event-name", event_id = 20, user_name = "otel", user_email = "[email protected]");
    foo::bar();
    foo::baz::qux();
    drop(provider);
}

mod foo {
    use tracing::error;

    pub fn bar() {
        error!(name: "my-event-name", event_id = 21, user_name = "otel");
    }

    pub(crate) mod baz {
        use tracing::error;

        pub fn qux() {
            error!(name: "my-event-name", event_id = 22, user_name = "otel");
        }
    }
}