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Full Linux VMs for your agents — VM Sandboxes

VM Sandboxes give agents a full Linux VM with root, outbound internet, and no fixed lifetime. Here is what changed and how to start using them.

By boxy

BoxCompute VM Sandboxes give your agents a full Linux virtual machine instead of a shared-kernel container. VM Sandboxes are now the default runtime for every account, so the same tools you'd run on a dedicated machine — install packages, build native modules, reach the internet — run inside an isolated, disposable VM by default.

From gVisor to VMs

We started with gVisor — a fast, minimal sandbox that shares the host kernel — and it's still available as an opt-out (vmSandbox: false). We made VMs the default because they're more flexible for integrations: a VM boots its own Linux kernel, so a guest can run as root, apt-get install packages, build native modules, and use tools that assume a full operating system. Most agent frameworks just work, without us special-casing their assumptions.

What a VM Sandbox gives you

  • Root inside the guest. You're UID 0 with HOME=/workspace.
  • Outbound internet by default. Public IPv4 and DNS. Pass blockNetwork: true for a no-NIC VM.
  • A real filesystem. One unified ~10 GiB root filesystem for / and /workspace.
  • No fixed lifetime. The VM stays billable until you delete it.
  • The same API. Create, execute, transfer files, and delete with the endpoints you already know.

Start using it

The easiest way is the CLI:

bxc login
bxc sandbox start WORKSPACE_ID      # a VM Sandbox by default
bxc sandbox status SANDBOX_ID       # poll until running
bxc sandbox exec SANDBOX_ID -- bash -c 'apt-get update && apt-get install -y gcc'
bxc sandbox delete SANDBOX_ID --yes

Start returns a pending VM that converges to running. VMs don't auto-expire — a VM Sandbox stays billable until you delete it, so delete it when you're done.

Prefer HTTP? Omit vmSandbox (or set true) for a VM, false to opt out to gVisor:

POST /api/v2/sandboxes
{ "workspaceId": "ws_...", "name": "my first VM" }

What's still beta

The profile is fixed for now: 0.5 CPU and 1 GiB of memory, a minimal Ubuntu image, no inbound ports or SSH, and no custom images or volumes. If you hit a boundary, tell us — this beta is how we decide what ships next.

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