crates/common: add bootstrap, tracing_init, and nix_probe modules

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: Ifbc17b000a4fb4a10e05ac9405582a366a6a6964

crates/common/src/tracing_init.rs

@@ -0,0 +1,51 @@
+//! Tracing initialization helper for all FC daemons.
+
+use tracing_subscriber::EnvFilter;
+use tracing_subscriber::fmt;
+
+use crate::config::TracingConfig;
+
+/// Initialize the global tracing subscriber based on configuration.
+///
+/// Respects `RUST_LOG` environment variable as an override. If `RUST_LOG` is
+/// not set, falls back to the configured level.
+pub fn init_tracing(config: &TracingConfig) {
+    let env_filter =
+        EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new(&config.level));
+
+    match config.format.as_str() {
+        "json" => {
+            let builder = fmt()
+                .json()
+                .with_target(config.show_targets)
+                .with_env_filter(env_filter);
+            if config.show_timestamps {
+                builder.init();
+            } else {
+                builder.without_time().init();
+            }
+        }
+        "full" => {
+            let builder = fmt()
+                .with_target(config.show_targets)
+                .with_env_filter(env_filter);
+            if config.show_timestamps {
+                builder.init();
+            } else {
+                builder.without_time().init();
+            }
+        }
+        _ => {
+            // "compact" or any other value
+            let builder = fmt()
+                .compact()
+                .with_target(config.show_targets)
+                .with_env_filter(env_filter);
+            if config.show_timestamps {
+                builder.init();
+            } else {
+                builder.without_time().init();
+            }
+        }
+    }
+}