Jan Novak
640bf5065a
A "poor man's" Firecracker VM orchestrator that boots a single golden VM,
snapshots it, then restores N clone VMs from that snapshot with minimal
per-clone overhead.
How it works:
- `init` — downloads a Linux 6.1 kernel and builds a minimal Alpine 3.20
rootfs (512 MiB ext4) with a basic init script
- `golden` — boots the golden VM, lets it settle, then pauses and snapshots
it (vmstate + memory file); the golden VMM is then terminated
since only the artifacts are needed
- `spawn N` — restores N clone VMs concurrently from the golden snapshot:
* rootfs: filesystem-level COW copy via `cp --reflink` (falls
back to a plain copy if reflinks are not supported)
* memory: shared golden `mem` file; Firecracker's MAP_PRIVATE
lets the kernel handle COW page-by-page at no up-front cost
* vmstate: small file, cheap regular copy per clone
* networking: per-clone TAP device (fctapN) bridged to fcbr0
with iptables MASQUERADE NAT on the default route interface
- `status` — reads PID files and checks /proc to report alive/dead clones
- `kill` — stops in-memory clones, kills any stragglers via PID files,
and tears down all fctap* devices
- `cleanup` — kill + remove all state dirs and the bridge
All tunables (binary path, base dir, kernel/rootfs paths, vCPUs, memory,
bridge name/CIDR) are configurable via environment variables.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>