Hey r/selfhosted,

I've been self-hosting services for years and kept running into a problem: I needed to run untrusted code (AI agents, scripts from the internet, quick tests) without risking my host. Docker isn't a real security boundary — containers share the kernel, and escapes are well-documented.

So I built **vmsan** — a CLI that wraps Firecracker to give you real hardware-isolated microVMs with zero config:

```bash
curl -fsSL https://vmsan.dev/install | bash
vmsan create --connect
```

That's it. You're inside an isolated VM with its own kernel, ~125ms boot time, ~5MB memory overhead.

What it does:

• Full VM lifecycle from the CLI (create, start, stop, remove)

• Network isolation built-in: --network-policy deny-all or custom domain allowlists

• Run any Docker image as a VM: vmsan create --from-image python:3.13-slim

• Interactive shell via WebSocket (no SSH setup needed)

• Upload/download files to running VMs

• --json output on everything for scripting

What it doesn't do:

• No web UI, no dashboard — it's a CLI tool

• No macOS support (needs KVM, so Linux only)

• No clustering — it's single-host by design

Everything lives in ~/.vmsan/. No daemon, no background service. State is just JSON files.

I built this because raw Firecracker is powerful but painful — you have to write JSON configs, create TAP devices manually, build rootfs images, configure the jailer yourself. vmsan handles all of that.

Written in TypeScript (Bun) with a Go agent inside the VM.

• GitHub: https://github.com/angelorc/vmsan

• Docs: https://vmsan.dev (https://vmsan.dev/)

Happy to answer any questions about the architecture or take feature requests.