v0.1.6 (#45)

## What's New?
Performance updates for large capsules, admin panel enhancement and bug fixes

### Envd
- Fixed bug with sandbox metrics calculation
- Page cache drop and balloon inflation to reduce memfile snapshot
- Updated rpc timeout logic for better control
- Added tests

### Admin Panel
- Add/Remove platform admin
- Updated template deletion logic for fine grained permission

### Others
- Minor frontend visual improvement
- Minor bugfixes
- Version bump

Co-authored-by: Tasnim Kabir Sadik <tksadik92@gmail.com>
Reviewed-on: wrenn/wrenn#45
Co-authored-by: pptx704 <rafeed@omukk.dev>
Co-committed-by: pptx704 <rafeed@omukk.dev>

envd-rs/src/main.rs

@@ -147,6 +147,14 @@ async fn main() {
         Some(Arc::clone(&port_subsystem)),
     );
 
+    // Memory reclaimer — drop page cache when available memory is low.
+    // Firecracker balloon device can only reclaim pages the guest kernel freed.
+    // Pauses during snapshot/prepare to avoid corrupting kernel page table state.
+    if !cli.is_not_fc {
+        let state_for_reclaimer = Arc::clone(&state);
+        std::thread::spawn(move || memory_reclaimer(state_for_reclaimer));
+    }
+
     // RPC services (Connect protocol — serves Connect + gRPC + gRPC-Web on same port)
     let connect_router = rpc::rpc_router(Arc::clone(&state));
 
@@ -188,7 +196,8 @@ fn spawn_initial_command(cmd: &str, state: &AppState) {
     use crate::rpc::process_handler;
     use std::collections::HashMap;
 
-    let user = match lookup_user(&state.defaults.user) {
+    let default_user = state.defaults.user();
+    let user = match lookup_user(&default_user) {
         Ok(u) => u,
         Err(e) => {
             tracing::error!(error = %e, "cmd: failed to lookup user");
@@ -197,9 +206,8 @@ fn spawn_initial_command(cmd: &str, state: &AppState) {
     };
 
     let home = user.dir.to_string_lossy().to_string();
-    let cwd = state
-        .defaults
-        .workdir
+    let default_workdir = state.defaults.workdir();
+    let cwd = default_workdir
         .as_deref()
         .unwrap_or(&home);
 
@@ -214,11 +222,52 @@ fn spawn_initial_command(cmd: &str, state: &AppState) {
         &user,
         &state.defaults.env_vars,
     ) {
-        Ok(handle) => {
-            tracing::info!(pid = handle.pid, cmd, "initial command spawned");
+        Ok(spawned) => {
+            tracing::info!(pid = spawned.handle.pid, cmd, "initial command spawned");
         }
         Err(e) => {
             tracing::error!(error = %e, cmd, "failed to spawn initial command");
         }
     }
 }
+
+fn memory_reclaimer(state: Arc<AppState>) {
+    use std::sync::atomic::Ordering;
+
+    const CHECK_INTERVAL: std::time::Duration = std::time::Duration::from_secs(10);
+    const DROP_THRESHOLD_PCT: u64 = 80;
+
+    loop {
+        std::thread::sleep(CHECK_INTERVAL);
+
+        if state.snapshot_in_progress.load(Ordering::Acquire) {
+            continue;
+        }
+
+        let mut sys = sysinfo::System::new();
+        sys.refresh_memory();
+        let total = sys.total_memory();
+        let available = sys.available_memory();
+
+        if total == 0 {
+            continue;
+        }
+
+        let used_pct = ((total - available) * 100) / total;
+        if used_pct >= DROP_THRESHOLD_PCT {
+            if state.snapshot_in_progress.load(Ordering::Acquire) {
+                continue;
+            }
+
+            if let Err(e) = std::fs::write("/proc/sys/vm/drop_caches", "3") {
+                tracing::debug!(error = %e, "drop_caches failed");
+            } else {
+                let mut sys2 = sysinfo::System::new();
+                sys2.refresh_memory();
+                let freed_mb =
+                    sys2.available_memory().saturating_sub(available) / (1024 * 1024);
+                tracing::info!(used_pct, freed_mb, "page cache dropped");
+            }
+        }
+    }
+}