@bsdkrun/sdk

A TypeScript SDK for bsdkrun — a Firecracker-style microVM launcher for BSD, Linux, and unikernel guests on macOS and Linux, built on libkrun. Boot and drive microVMs programmatically, inspired by the Vercel and Deno Sandbox SDKs.

Runs on Node.js, Deno, and Bun — the SDK shells out to the bsdkrun binary, so it has zero npm dependencies.

import { Sandbox } from "@bsdkrun/sdk";

const box = await Sandbox.create({ os: "linux", image: "alpine" });

// Tagged-template shell — interpolations are shell-quoted for you:
const kernel = await box.sh`uname -a`.text();

// ...or exec argv directly, with env / stdin / a PTY / a working dir:
await box.exec(["apk", "add", "curl"]);
await box.runCommand("curl", ["-fsSL", "https://example.com"]);

await box.stop();

Install

bun  add @bsdkrun/sdk
npm  install @bsdkrun/sdk
deno add npm:@bsdkrun/sdk

libkrun is provisioned on install

bsdkrun links libkrun (Apple's Hypervisor.framework on macOS, KVM on Linux). A postinstall step provisions it for you when you install this package:

• macOS — brew install libkrun (if not already installed).
• Linux — downloads our PVH-enabled libkrun fork (needed for BSD PVH boots; not packaged elsewhere) into the bsdkrun cache and, at runtime, points the loader at it via LD_LIBRARY_PATH. You still need libkrunfw (the bundled-kernel lib it links) from your distro / nixpkgs, and /dev/kvm access.

If postinstall was skipped (--ignore-scripts, or Deno, which doesn't run install hooks), the SDK provisions libkrun the same way on its first call.

Provisioning knobs:

| Env var | Effect | | ---------------------------- | -------------------------------------------------- | | BSDKRUN_NO_AUTO_INSTALL=1 | Skip all provisioning — you manage libkrun. | | BSDKRUN_LIBKRUN_DIR=/path | Use an already-extracted libkrun lib dir (Linux). | | BSDKRUN_LIBKRUN_VERSION=vX | Pin a specific PVH-fork release tag. |

The bsdkrun binary

You also need the bsdkrun binary itself. The SDK finds it via, in order:

1. setBinaryPath("/path/to/bsdkrun")
2. the BSDKRUN_BIN environment variable
3. bsdkrun on your PATH
4. an in-repo target/release/bsdkrun or target/debug/bsdkrun build

See the bsdkrun README for installing the binary (Homebrew on macOS, or build from source on Linux/KVM).

Creating a sandbox

Sandbox.create is a discriminated union on os — the options change per guest kind:

// Linux OCI image (docker run-style)
await Sandbox.create({
  os: "linux",
  image: "ghcr.io/owner/name:tag",
  cpus: 2,
  mem: 1024,
  volume: "web",                     // persistent CoW rootfs
  mounts: ["~/project:/src", "~/data:/data:ro"],
  net: { ports: ["8080:80", "2222:22"] },
  command: ["node", "server.js"],    // args after `--`
});

// FreeBSD (EFI on macOS, PVH on Linux/amd64)
await Sandbox.create({ os: "freebsd", version: "14.3", mem: 2048 });

// NetBSD (direct-kernel boot everywhere)
await Sandbox.create({ os: "netbsd", version: "10.1", volume: "db" });

// Boot a raw disk through its UEFI loader
await Sandbox.create({ os: "firmware", firmware: "KRUN_EFI.fd", disk: "disk.raw" });

// Boot a kernel directly, no bootloader
await Sandbox.create({ os: "kernel", kernel: "netbsd", format: "elf", disk: "root.raw" });

Every create runs the machine detached and returns a Sandbox handle.

Running commands

Two complementary APIs:

sh — tagged template

Best for quick shell one-liners. Interpolated values are single-quoted (injection-safe); wrap a value in raw() to splice it verbatim.

const dir = "/etc";
await box.sh`ls -la ${dir}`;                 // quoted
await box.sh`grep ${pattern} /var/log/*`;    // quoted

await box.sh`cat /nope`.nothrow();           // don't throw on non-zero exit
await box.sh`echo $X`.env({ X: "1" }).text();

import { raw } from "@bsdkrun/sdk";
await box.sh`ls ${raw("-la /var")}`;         // spliced verbatim (trusted only)

An sh call is lazy and awaitable; .text(), .json(), .lines() are convenience accessors. It throws CommandFailedError on a non-zero exit unless you call .nothrow().

exec — argv, with options

The primary programmatic entrypoint. No shell parsing; pass an argv array (or a program name plus args). Richer options than sh:

await box.exec(["ls", "-la", "/etc"]);

await box.exec("node", {
  args: ["-e", "console.log(process.env.X)"],
  env: { X: "hi" },
  cwd: "/app",
  stdin: "data on stdin",
  tty: true,               // allocate a PTY
  throwOnError: true,      // throw on non-zero exit (default: false)
});

// Vercel-Sandbox-style alias:
const { stdout, exitCode } = await box.runCommand("uname", ["-a"]);

exec returns a CommandResult with .stdout, .stderr, .exitCode, .ok, and helpers .text(), .json(), .lines(), .throwIfFailed().

exec/shell talk to a tiny in-guest agent (needs guest networking). Linux guests get it injected automatically; on BSD you install it once — see the bsdkrun README.

Lifecycle & inventory

const box  = await Sandbox.create({ os: "linux", image: "alpine", command: ["sleep","300"] });
const same = await Sandbox.get(box.id);        // reconnect (prefix ok)
const list = await Sandbox.list({ all: true }); // SandboxInfo[]

await box.status();      // SandboxInfo | null
await box.isRunning();   // boolean
await box.logs();        // console log (string)
box.followLogs();        // live stream (child process)
box.shell();             // interactive shell (inherits the terminal)
await box.stop();        // BSD guests clean-poweroff; Linux SIGTERM
await box.start();       // restart in place — resumes its own disk/rootfs (data persists)
await box.update({ cpus: 4, mem: 2048 }); // applies on next start
await box.remove({ force: true });

stop/start persist your data: start resumes the machine's own disk/rootfs (any committed snapshot + runtime changes), like docker start.

Host-level namespaces:

import { images, volumes, networks, probe, fetchImage, versions } from "@bsdkrun/sdk";

await probe();                              // toolchain sanity check
await images.list();                        // ImageInfo[]
await volumes.list();                       // VolumeInfo[]
await volumes.remove("web", { force: true });
await networks.list();                      // NetworkInfo[]
await fetchImage("freebsd", { version: "14.3" });
await versions("netbsd");

Interactive terminal (xterm.js in the browser)

box.terminal() opens a PTY session in the guest, streamed over the agent's TCP protocol — with live window-resize. It's shaped to drop straight into xterm.js: pipe output in, forward keystrokes out, resize on demand.

const term = await box.terminal({ command: ["/bin/sh"], cols: 120, rows: 30 });

term.onData((chunk) => xterm.write(chunk));      // guest → xterm
xterm.onData((input) => term.write(input));      // xterm → guest
xterm.onResize(({ cols, rows }) => term.resize(cols, rows));

const code = await term.exited;                  // resolves when the shell exits

Server-side, bridge it to a browser over a WebSocket in one call:

wss.on("connection", async (ws) => {
  const term = await box.terminal();
  term.bindWebSocket(ws);   // wires output, input, and {"resize":[c,r]} frames
});

See examples/08-browser-terminal for a complete Bun server + xterm.js page.

Networking, SSH & Tailscale

// forward ports at create time
await Sandbox.create({ os: "linux", image: "alpine", net: { ports: ["2222:22"] } });

// agent-managed key-based SSH (typed helpers)
await box.ssh.setup();                              // install local ~/.ssh/*.pub keys
await box.ssh.setup({ user: "tsiry", key: "~/.ssh/work.pub" });
await box.ssh.addKey("ssh-ed25519 AAAA...");
await box.ssh.status();

// put a guest on your tailnet
await box.tailscale.up({ authkey: "tskey-auth-...", hostname: "web" });
await box.tailscale.status();

// turn a Linux guest into a systemd system (debian/ubuntu/fedora only —
// not Alpine, not the BSD guests)
await box.systemd.setup();

Global networks — reach machines by name

Opt machines into a shared network so they get distinct IPs on one subnet and reach each other by IP and by name (docker-compose style), with internal DNS:

import { Sandbox, networks } from "@bsdkrun/sdk";

await networks.create("devnet");

const db  = await Sandbox.create({ os: "linux", image: "postgres", name: "db",  net: { network: "devnet" } });
const api = await Sandbox.create({ os: "linux", image: "myapi",    name: "api", net: { network: "devnet" } });

await api.sh`ping -c1 db`;              // resolves db → its IP on devnet

// inspect + manage
await networks.list();                 // NetworkInfo[]
await networks.members("devnet");      // SandboxInfo[] on the network
const info = await db.status();        // info.network === "devnet", info.netIp set

// edit membership (applies on next start — a VM's NIC is fixed at boot)
await api.connectNetwork("devnet");    // or networks.connect(api.id, "devnet")
await api.disconnectNetwork();
await api.start();                     // re-joins with the new membership

await networks.sync("devnet");         // refresh members' /etc/hosts (fixes NetBSD name lookup)
await networks.remove("devnet", { force: true });

Names resolve on Linux and FreeBSD via the network's DNS; NetBSD resolves via a synced /etc/hosts block (its resolver rejects the DNS's AAAA NXDOMAIN) — joins auto-sync, and networks.sync refreshes an existing network without restarting members.

Connecting to a remote daemon

Everything above talks to a local bsdkrun binary. Client is the network sibling: it drives the same operations against a remote bsdkrund over its GraphQL API — no local binary needed, just a URL and a bearer token.

import { Client } from "@bsdkrun/sdk";

const client = new Client({ url: "http://vps.example.com:50052", token: "9f2c..." });
// or, from BSDKRUN_URL / BSDKRUN_TOKEN:
const client = Client.fromEnv();

const machines = await client.list(true);   // SandboxInfo[] — same type Sandbox.list() returns
const id = await client.runLinux({ image: "alpine", cpus: 2, mem: 1024, command: ["sleep", "300"] });

const { exitCode, output } = await client.exec(id, ["uname", "-a"]);
console.log(new TextDecoder().decode(output), exitCode);

await client.stop(id);
await client.remove([id]);

client.runLinux/runBsd/runNanos/runUnikraft/runSolo5/runOsv/ runFlavor each take the same fields as the corresponding GraphQL mutation (daemon/src/graphql.rs) — runBsd({ os: "FREEBSD", ... }), etc. — and return the new machine's id. runSolo5 boots a MirageOS unikernel under the solo5-hvt tender rather than libkrun: runSolo5({ path: "dist/hello.hvt", args: ["--ipv4=10.0.0.2/24"] }). stop/start/remove/update/commit return a RemoteCommandResult ({exitCode, stdout, stderr}).

For a live terminal instead of a one-shot exec, use shell():

const session = await client.shell(id);   // or shell(id, { command: [...] }) for a non-login command
session.onOutput((chunk) => process.stdout.write(chunk));
session.onExit((code) => console.log(`exited ${code}`));
session.write("ls -la\n");
session.resize(50, 120);
session.close();

followLogs(id, {}, { onData, onError, onComplete }) streams a machine's console live instead of the one-shot logs(id). Both exec/shell and followLogs are built on the same openShell/shellOutput shell-session protocol the daemon uses for every interactive terminal — see daemon/README.md for the wire-level story.

Not every GraphQL operation has a typed method yet (flavor/network/volume management, for instance) — client.request(query, variables) runs any raw query or mutation, and client.subscribe(query, variables, { onNext, ... }) runs any raw subscription, for anything not wrapped above.

Like the rest of this SDK, Client has zero npm dependencies — the HTTP transport is the platform's global fetch, and subscriptions (used by exec/shell/followLogs) run over the platform's global WebSocket speaking graphql-transport-ws directly (no graphql-ws/Apollo/urql).

new Client({...}) and Client.fromEnv() both reject a URL configured without a token rather than silently making an unauthenticated request — set both BSDKRUN_URL and BSDKRUN_TOKEN, or pass both explicitly.

Errors

All errors extend BsdkrunError:

• BinaryNotFoundError — the bsdkrun binary wasn't found.
• CommandFailedError — a command exited non-zero (carries exitCode, stdout, stderr). Thrown by sh (unless .nothrow()), by exec with throwOnError, and by the agent helpers.
• SandboxNotFoundError — Sandbox.get matched no machine.
• GraphQLError — a Client request failed (carries code, the daemon's extensions.code, when there is one).
• AuthError (a GraphQLError) — the daemon rejected the bearer token.

Examples

See examples/ for runnable scripts covering every feature above.

License

MIT