Three issues fixed:
1. Memory metrics read host-side VmRSS of the Firecracker process,
which includes guest page cache and never decreases. Replaced
readMemRSS(fcPID) with readEnvdMemUsed(client) that queries
envd's /metrics endpoint for guest-side total - MemAvailable.
This matches neofetch and reflects actual process memory.
2. Added Firecracker balloon device (deflate_on_oom, 5s stats) and
envd-side periodic page cache reclaimer (drop_caches when >80%
used). Reclaimer is gated by snapshot_in_progress flag with
sync() before freeze to prevent memory corruption during pause.
3. Sampling interval 500ms → 1s, ring buffer capacities adjusted
to maintain same time windows. Reduces per-host HTTP load from
240 calls/sec to 120 calls/sec at 120 capsules.
Also: maxDiffGenerations 8 → 1 (merge every re-pause since UFFD
lazy-loads anyway), envd mem_used formula uses total - available.
- New detail page at /dashboard/capsules/[id] with Stats and Files tabs
- Stats tab shows capsule info card (status, template, CPU, memory, disk,
started, idle timeout) and two stacked Chart.js charts with live values
- Metrics API client with 10s polling and moving-average smoothing
- Capsule ID in list table is now a clickable link to the detail page
- Layout breadcrumb header (Capsules > sb-xxx) with back navigation
- Fix metrics sampler: use v.PID() directly as Firecracker PID since
unshare -m execs (not forks) through the bash/ip-netns-exec/firecracker
chain, so all share the same PID. Removes unused findChildPID.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Samples /proc/{fc_pid}/stat (CPU%), /proc/{fc_pid}/status (VmRSS), and
stat() on CoW files at 500ms intervals per running sandbox. Three tiered
ring buffers downsample into 30s and 5min averages for 10min/2h/24h
retention. Metrics are flushed to DB on pause (all tiers) and destroy
(24h only). New GetSandboxMetrics and FlushSandboxMetrics RPCs on the
host agent, proxied through GET /v1/sandboxes/{id}/metrics?range= on
the control plane. Returns live data for running sandboxes, DB data for
paused, and 404 for stopped.
