feat(tracing): log nothing unless RUST_LOG is set

Author: rami3l

doc/dev-guide/src/tracing.md

@@ -30,7 +30,7 @@ cargo build --features=otel
 Run the operation you want to analyze:
 
 ```sh
-RUSTUP_FORCE_ARG0="rustup" ./target/debug/rustup-init show
+RUST_LOG='info' RUSTUP_FORCE_ARG0='rustup' ./target/debug/rustup-init show
 ```
 
 And [look in Jaeger for a trace](http://localhost:16686/search?service=rustup).

src/bin/rustup-init.rs

@@ -85,7 +85,7 @@ fn maybe_trace_rustup() -> Result<utils::ExitCode> {
                         )])),
                 )
                 .install_batch(opentelemetry_sdk::runtime::Tokio)?;
-            let env_filter = EnvFilter::try_from_default_env().unwrap_or(EnvFilter::new("INFO"));
+            let env_filter = EnvFilter::try_from_default_env().unwrap_or(EnvFilter::new("OFF"));
             let telemetry = tracing_opentelemetry::layer().with_tracer(tracer);
             let subscriber = Registry::default().with(env_filter).with(telemetry);
             tracing::subscriber::set_global_default(subscriber)?;

src/test.rs

@@ -270,7 +270,7 @@ static TRACER: Lazy<opentelemetry_sdk::trace::Tracer> = Lazy::new(|| {
         .unwrap();
 
     global::set_text_map_propagator(TraceContextPropagator::new());
-    let env_filter = EnvFilter::try_from_default_env().unwrap_or(EnvFilter::new("INFO"));
+    let env_filter = EnvFilter::try_from_default_env().unwrap_or(EnvFilter::new("OFF"));
     let telemetry = tracing_opentelemetry::layer().with_tracer(tracer.clone());
     let subscriber = Registry::default().with(env_filter).with(telemetry);
     tracing::subscriber::set_global_default(subscriber).unwrap();