fix: resolve PTY failure, MMDS file writes, and metrics instability in envd-rs

Three bugs fixed:

1. PTY connections failed because home directory was hardcoded as
   /home/{username} instead of reading from /etc/passwd. For root,
   this produced /home/root/ which doesn't exist — CWD validation
   rejected every PTY Start request without explicit cwd. Fixed all
   6 locations to use user.dir from nix::unistd::User.

2. MMDS polling silently failed to parse metadata because the
   logs_collector_address field lacked #[serde(default)]. The host
   agent only sends instanceID + envID — missing "address" field
   caused every deserialize attempt to fail, so .WRENN_SANDBOX_ID
   and .WRENN_TEMPLATE_ID were never written. Also added error
   logging and create_dir_all before file writes.

3. Metrics CPU values were non-deterministic because a fresh
   sysinfo::System was created per request with a 100ms sleep
   between reads. Replaced with a background thread that samples
   CPU at fixed 1-second intervals via a persistent System instance,
   matching gopsutil's internal caching behavior. Metrics endpoint
   now reads cached atomic values — no blocking, consistent window.

Also: close master PTY fd in child pre_exec, add process.Start
request logging, bump version to 0.2.0.

envd-rs/Cargo.lock

@@ -514,7 +514,7 @@ dependencies = [
 
 [[package]]
 name = "envd"
-version = "0.1.2"
+version = "0.2.0"
 dependencies = [
  "async-stream",
  "axum",

envd-rs/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "envd"
-version = "0.1.2"
+version = "0.2.0"
 edition = "2024"
 rust-version = "1.88"
 

envd-rs/src/host/mmds.rs

@@ -13,7 +13,7 @@ pub struct MMDSOpts {
     pub sandbox_id: String,
     #[serde(rename = "envID")]
     pub template_id: String,
-    #[serde(rename = "address")]
+    #[serde(rename = "address", default)]
     pub logs_collector_address: String,
     #[serde(rename = "accessTokenHash", default)]
     pub access_token_hash: String,
@@ -103,8 +103,15 @@ pub async fn poll_for_opts(
                 env_vars.insert("WRENN_TEMPLATE_ID".into(), opts.template_id.clone());
 
                 let run_dir = std::path::Path::new(WRENN_RUN_DIR);
-                let _ = std::fs::write(run_dir.join(".WRENN_SANDBOX_ID"), &opts.sandbox_id);
-                let _ = std::fs::write(run_dir.join(".WRENN_TEMPLATE_ID"), &opts.template_id);
+                if let Err(e) = std::fs::create_dir_all(run_dir) {
+                    tracing::error!(error = %e, "mmds: failed to create run dir");
+                }
+                if let Err(e) = std::fs::write(run_dir.join(".WRENN_SANDBOX_ID"), &opts.sandbox_id) {
+                    tracing::error!(error = %e, "mmds: failed to write .WRENN_SANDBOX_ID");
+                }
+                if let Err(e) = std::fs::write(run_dir.join(".WRENN_TEMPLATE_ID"), &opts.template_id) {
+                    tracing::error!(error = %e, "mmds: failed to write .WRENN_TEMPLATE_ID");
+                }
 
                 return Some(opts);
             }

envd-rs/src/http/files.rs

@@ -95,7 +95,7 @@ pub async fn get_files(
         Err(e) => return json_error(StatusCode::UNAUTHORIZED, &e),
     };
 
-    let home_dir = format!("/home/{}", user.name);
+    let home_dir = user.dir.to_string_lossy().to_string();
     let resolved = match expand_and_resolve(path_str, &home_dir, state.defaults.workdir.as_deref())
     {
         Ok(p) => p,
@@ -246,7 +246,7 @@ pub async fn post_files(
         Err(e) => return json_error(StatusCode::UNAUTHORIZED, &e),
     };
 
-    let home_dir = format!("/home/{}", user.name);
+    let home_dir = user.dir.to_string_lossy().to_string();
     let uid = user.uid;
     let gid = user.gid;
 

envd-rs/src/http/metrics.rs

@@ -22,10 +22,10 @@ pub struct Metrics {
     disk_total: u64,
 }
 
-pub async fn get_metrics(State(_state): State<Arc<AppState>>) -> impl IntoResponse {
+pub async fn get_metrics(State(state): State<Arc<AppState>>) -> impl IntoResponse {
     tracing::trace!("get metrics");
 
-    match collect_metrics() {
+    match collect_metrics(&state) {
         Ok(m) => (
             StatusCode::OK,
             [(header::CACHE_CONTROL, "no-store")],
@@ -39,26 +39,12 @@ pub async fn get_metrics(State(_state): State<Arc<AppState>>) -> impl IntoRespon
     }
 }
 
-fn collect_metrics() -> Result<Metrics, String> {
-    use sysinfo::System;
+fn collect_metrics(state: &AppState) -> Result<Metrics, String> {
+    let cpu_count = state.cpu_count();
+    let cpu_used_pct_rounded = state.cpu_used_pct();
 
-    let mut sys = System::new();
+    let mut sys = sysinfo::System::new();
     sys.refresh_memory();
-    sys.refresh_cpu_all();
-
-    // sysinfo needs a small delay for accurate CPU — first call returns 0.
-    // In a real daemon this would be cached; for now, report instantaneous.
-    std::thread::sleep(std::time::Duration::from_millis(100));
-    sys.refresh_cpu_all();
-
-    let cpu_count = sys.cpus().len() as u32;
-    let cpu_used_pct = sys.global_cpu_usage();
-    let cpu_used_pct_rounded = if cpu_used_pct > 0.0 {
-        (cpu_used_pct * 100.0).round() / 100.0
-    } else {
-        0.0
-    };
-
     let mem_total = sys.total_memory();
     let mem_used = sys.used_memory();
     let mem_total_mib = mem_total / 1024 / 1024;

envd-rs/src/main.rs

@@ -196,7 +196,7 @@ fn spawn_initial_command(cmd: &str, state: &AppState) {
         }
     };
 
-    let home = format!("/home/{}", user.name);
+    let home = user.dir.to_string_lossy().to_string();
     let cwd = state
         .defaults
         .workdir

envd-rs/src/rpc/filesystem_service.rs

@@ -36,7 +36,7 @@ impl FilesystemServiceImpl {
             ConnectError::new(ErrorCode::Unauthenticated, format!("invalid user: {e}"))
         })?;
 
-        let home_dir = format!("/home/{}", user.name);
+        let home_dir = user.dir.to_string_lossy().to_string();
         let default_workdir = self.state.defaults.workdir.as_deref();
 
         expand_and_resolve(path, &home_dir, default_workdir)

envd-rs/src/rpc/process_handler.rs

@@ -141,7 +141,7 @@ pub fn spawn_process(
 ) -> Result<Arc<ProcessHandle>, ConnectError> {
     let mut env: Vec<(String, String)> = Vec::new();
     env.push(("PATH".into(), std::env::var("PATH").unwrap_or_default()));
-    let home = format!("/home/{}", user.name);
+    let home = user.dir.to_string_lossy().to_string();
     env.push(("HOME".into(), home));
     env.push(("USER".into(), user.name.clone()));
     env.push(("LOGNAME".into(), user.name.clone()));
@@ -206,7 +206,9 @@ pub fn spawn_process(
         unsafe {
             use std::os::unix::io::AsRawFd;
             let slave_raw = slave_fd.as_raw_fd();
+            let master_raw = master_fd.as_raw_fd();
             command.pre_exec(move || {
+                libc::close(master_raw);
                 nix::unistd::setsid()
                     .map_err(|e| std::io::Error::new(std::io::ErrorKind::Other, e))?;
                 libc::ioctl(slave_raw, libc::TIOCSCTTY, 0);

envd-rs/src/rpc/process_service.rs

@@ -83,7 +83,7 @@ impl ProcessServiceImpl {
             .map(|(k, v)| (k.to_string(), v.to_string()))
             .collect();
 
-        let home_dir = format!("/home/{}", user.name);
+        let home_dir = user.dir.to_string_lossy().to_string();
         let cwd_str: &str = proc_config.cwd.unwrap_or("");
         let cwd = expand_and_resolve(cwd_str, &home_dir, self.state.defaults.workdir.as_deref())
             .map_err(|e| ConnectError::new(ErrorCode::InvalidArgument, e))?;
@@ -105,6 +105,17 @@ impl ProcessServiceImpl {
         let enable_stdin = request.stdin.unwrap_or(true);
         let tag = request.tag.map(|s| s.to_string());
 
+        tracing::info!(
+            cmd = cmd,
+            has_pty = pty_opts.is_some(),
+            pty_size = ?pty_opts,
+            tag = ?tag,
+            stdin = enable_stdin,
+            cwd = effective_cwd,
+            user = %username,
+            "process.Start request"
+        );
+
         let handle = process_handler::spawn_process(
             cmd,
             &args,

envd-rs/src/state.rs

@@ -1,4 +1,4 @@
-use std::sync::atomic::AtomicBool;
+use std::sync::atomic::{AtomicBool, AtomicU32, Ordering};
 use std::sync::Arc;
 
 use crate::auth::token::SecureToken;
@@ -17,6 +17,8 @@ pub struct AppState {
     pub access_token: SecureToken,
     pub conn_tracker: ConnTracker,
     pub port_subsystem: Option<Arc<PortSubsystem>>,
+    pub cpu_used_pct: AtomicU32,
+    pub cpu_count: AtomicU32,
 }
 
 impl AppState {
@@ -27,7 +29,7 @@ impl AppState {
         is_fc: bool,
         port_subsystem: Option<Arc<PortSubsystem>>,
     ) -> Arc<Self> {
-        Arc::new(Self {
+        let state = Arc::new(Self {
             defaults,
             version,
             commit,
@@ -37,6 +39,49 @@ impl AppState {
             access_token: SecureToken::new(),
             conn_tracker: ConnTracker::new(),
             port_subsystem,
-        })
+            cpu_used_pct: AtomicU32::new(0),
+            cpu_count: AtomicU32::new(0),
+        });
+
+        let state_clone = Arc::clone(&state);
+        std::thread::spawn(move || {
+            cpu_sampler(state_clone);
+        });
+
+        state
+    }
+
+    pub fn cpu_used_pct(&self) -> f32 {
+        f32::from_bits(self.cpu_used_pct.load(Ordering::Relaxed))
+    }
+
+    pub fn cpu_count(&self) -> u32 {
+        self.cpu_count.load(Ordering::Relaxed)
+    }
+}
+
+fn cpu_sampler(state: Arc<AppState>) {
+    use sysinfo::System;
+
+    let mut sys = System::new();
+    sys.refresh_cpu_all();
+
+    loop {
+        std::thread::sleep(std::time::Duration::from_secs(1));
+        sys.refresh_cpu_all();
+
+        let pct = sys.global_cpu_usage();
+        let rounded = if pct > 0.0 {
+            (pct * 100.0).round() / 100.0
+        } else {
+            0.0
+        };
+
+        state
+            .cpu_used_pct
+            .store(rounded.to_bits(), Ordering::Relaxed);
+        state
+            .cpu_count
+            .store(sys.cpus().len() as u32, Ordering::Relaxed);
     }
 }