server: misc changes for traces

src/core/common.rs

@@ -4,6 +4,7 @@ use nix::unistd::{Group as LibcGroup, User as LibcUser};
 
 #[cfg(not(target_os = "macos"))]
 use std::ffi::CString;
+use std::fmt;
 
 pub const DEFAULT_CONFIG_PATH: &str = "/etc/muscl/config.toml";
 pub const DEFAULT_SOCKET_PATH: &str = "/run/muscl/muscl.sock";
@@ -24,6 +25,12 @@ pub struct UnixUser {
     pub groups: Vec<String>,
 }
 
+impl fmt::Display for UnixUser {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(&self.username)
+    }
+}
+
 // TODO: these functions are somewhat critical, and should have integration tests
 
 #[cfg(target_os = "macos")]