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/http/snapshot.rs

@@ -10,10 +10,24 @@ use crate::state::AppState;
 /// POST /snapshot/prepare — quiesce subsystems before Firecracker snapshot.
 ///
 /// In Rust there is no GC dance. We just:
-/// 1. Stop port subsystem
-/// 2. Close idle connections via conntracker
-/// 3. Set needs_restore flag
+/// 1. Drop page cache to shrink snapshot size
+/// 2. Stop port subsystem
+/// 3. Close idle connections via conntracker
+/// 4. Set needs_restore flag
 pub async fn post_snapshot_prepare(State(state): State<Arc<AppState>>) -> impl IntoResponse {
+    // Drop page cache BEFORE blocking the reclaimer — avoids snapshotting
+    // gigabytes of stale cache that inflates the memory dump on disk.
+    // "1" = pagecache only (keep dentries/inodes for faster resume).
+    if let Err(e) = std::fs::write("/proc/sys/vm/drop_caches", "1") {
+        tracing::warn!(error = %e, "snapshot/prepare: drop_caches failed");
+    } else {
+        tracing::info!("snapshot/prepare: page cache dropped");
+    }
+
+    // Block memory reclaimer — prevents drop_caches from running mid-freeze
+    // which would corrupt kernel page table state.
+    state.snapshot_in_progress.store(true, Ordering::Release);
+
     if let Some(ref ps) = state.port_subsystem {
         ps.stop();
         tracing::info!("snapshot/prepare: port subsystem stopped");
@@ -22,6 +36,9 @@ pub async fn post_snapshot_prepare(State(state): State<Arc<AppState>>) -> impl I
     state.conn_tracker.prepare_for_snapshot();
     tracing::info!("snapshot/prepare: connections prepared");
 
+    // Sync filesystem buffers so dirty pages are flushed before freeze.
+    unsafe { libc::sync(); }
+
     state.needs_restore.store(true, Ordering::Release);
     tracing::info!("snapshot/prepare: ready for freeze");