tracing

[conradludgate]

Adds tracing support and some simple instrumentations :)

For now, this doesn't log much new. example log line:

Before:

After:

The more info you add to the spans (and the more spans you have), the more you'll see in these events.

[conradludgate]

With just a few lines of code

pub async fn run(self) -> Result<()> {
+        let tracer = opentelemetry_jaeger::new_pipeline().install_simple()?;
+
         tracing_subscriber::registry()
             .with(fmt::layer())
             .with(EnvFilter::from_default_env())
+            .with(tracing_opentelemetry::layer().with_tracer(tracer))
             .init();

we can get nice traces like this :)

[conradludgate]

The reasoning for skip_all is that it's usually better form to opt_in which fields you want to log (for PII as well as just for noisy structs like db handles).

In tracing 0.2, this will be the default: tokio-rs/tracing#651