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>

internal/vm/fc.go

@@ -8,7 +8,6 @@ import (
 	"io"
 	"net"
 	"net/http"
-	"time"
 )
 
 // fcClient talks to the Firecracker HTTP API over a Unix socket.
@@ -27,7 +26,9 @@ func newFCClient(socketPath string) *fcClient {
 					return d.DialContext(ctx, "unix", socketPath)
 				},
 			},
-			Timeout: 10 * time.Second,
+			// No global timeout — callers pass context.Context with appropriate
+			// deadlines. A fixed 10s timeout was too short for snapshot/resume
+			// operations on large-memory VMs (20GB+ memfiles).
 		},
 	}
 }
@@ -136,6 +137,25 @@ func (c *fcClient) setMMDS(ctx context.Context, sandboxID, templateID string) er
 	})
 }
 
+// setBalloon configures the Firecracker balloon device for dynamic memory
+// management. deflateOnOom lets the guest reclaim balloon pages under memory
+// pressure. statsInterval enables periodic stats via GET /balloon/statistics.
+// Must be called before startVM.
+func (c *fcClient) setBalloon(ctx context.Context, amountMiB int, deflateOnOom bool, statsIntervalS int) error {
+	return c.do(ctx, http.MethodPut, "/balloon", map[string]any{
+		"amount_mib":             amountMiB,
+		"deflate_on_oom":         deflateOnOom,
+		"stats_polling_interval_s": statsIntervalS,
+	})
+}
+
+// updateBalloon adjusts the balloon target at runtime.
+func (c *fcClient) updateBalloon(ctx context.Context, amountMiB int) error {
+	return c.do(ctx, http.MethodPatch, "/balloon", map[string]any{
+		"amount_mib": amountMiB,
+	})
+}
+
 // startVM issues the InstanceStart action.
 func (c *fcClient) startVM(ctx context.Context) error {
 	return c.do(ctx, http.MethodPut, "/actions", map[string]string{

internal/vm/manager.go

@@ -119,6 +119,13 @@ func configureVM(ctx context.Context, client *fcClient, cfg *VMConfig) error {
 		return fmt.Errorf("set machine config: %w", err)
 	}
 
+	// Balloon device — allows the host to reclaim unused guest memory.
+	// Start with 0 (no inflation). deflate_on_oom lets the guest reclaim
+	// balloon pages under memory pressure. Stats interval enables monitoring.
+	if err := client.setBalloon(ctx, 0, true, 5); err != nil {
+		slog.Warn("set balloon failed (non-fatal, VM will run without memory reclaim)", "error", err)
+	}
+
 	// MMDS config — enable V2 token access on eth0 so that envd can read
 	// WRENN_SANDBOX_ID and WRENN_TEMPLATE_ID from inside the guest.
 	if err := client.setMMDSConfig(ctx, "eth0"); err != nil {
@@ -162,6 +169,19 @@ func (m *Manager) Resume(ctx context.Context, sandboxID string) error {
 	return nil
 }
 
+// UpdateBalloon adjusts the balloon target for a running VM.
+// amountMiB is memory to take FROM the guest (0 = give all back).
+func (m *Manager) UpdateBalloon(ctx context.Context, sandboxID string, amountMiB int) error {
+	m.mu.RLock()
+	vm, ok := m.vms[sandboxID]
+	m.mu.RUnlock()
+	if !ok {
+		return fmt.Errorf("VM not found: %s", sandboxID)
+	}
+
+	return vm.client.updateBalloon(ctx, amountMiB)
+}
+
 // Destroy stops and cleans up a VM.
 func (m *Manager) Destroy(ctx context.Context, sandboxID string) error {
 	m.mu.Lock()