fix: Only enable tokio components for servers

Only enable the tokio and tracing components for server commands.

zebrad/src/application.rs

@@ -84,11 +84,15 @@ impl Application for ZebradApp {
         &mut self,
         command: &Self::Cmd,
     ) -> Result<Vec<Box<dyn Component<Self>>>, FrameworkError> {
-        let terminal = Terminal::new(self.term_colors(command));
-        let tracing = self.tracing_component(command);
         color_eyre::install().unwrap();
 
+        let terminal = Terminal::new(self.term_colors(command));
+        if ZebradApp::command_is_server(&command) {
+            let tracing = self.tracing_component(command);
             Ok(vec![Box::new(terminal), Box::new(tracing)])
+        } else {
+            Ok(vec![Box::new(terminal)])
+        }
     }
 
     /// Register all components used by this application.
@@ -101,16 +105,10 @@ impl Application for ZebradApp {
             metrics::MetricsEndpoint, tokio::TokioComponent, tracing::TracingEndpoint,
         };
 
-        // `None` outputs zebrad usage information and exits
-        let command_is_server = match &command.command {
-            None => false,
-            Some(c) => c.is_server(),
-        };
-
         let mut components = self.framework_components(command)?;
-        components.push(Box::new(TokioComponent::new()?));
         // Launch network endpoints for long-running commands
-        if command_is_server {
+        if ZebradApp::command_is_server(&command) {
+            components.push(Box::new(TokioComponent::new()?));
             components.push(Box::new(TracingEndpoint::new()?));
             components.push(Box::new(MetricsEndpoint::new()?));
         }
@@ -132,12 +130,14 @@ impl Application for ZebradApp {
         self.state.components.after_config(&config)?;
         self.config = Some(config);
 
+        if ZebradApp::command_is_server(&command) {
             let level = self.level(command);
             self.state
                 .components
                 .get_downcast_mut::<Tracing>()
                 .expect("Tracing component should be available")
                 .reload_filter(level);
+        }
 
         Ok(())
     }
@@ -198,4 +198,16 @@ impl ZebradApp {
 
         filter_handle.into()
     }
+
+    /// Returns true if command is a server command.
+    ///
+    /// Server commands use long-running components such as tracing, metrics,
+    /// and the tokio runtime.
+    fn command_is_server(command: &EntryPoint<ZebradCmd>) -> bool {
+        // `None` outputs zebrad usage information and exits
+        match &command.command {
+            None => false,
+            Some(c) => c.is_server(),
+        }
+    }
 }