Run untrusted code on BoxLite Cloud - BoxLite Documentation

BoxLite Cloud runs your boxes on BoxLite’s own resource pool, so the machine that calls the API needs nothing but a URL and an API key. Untrusted code still lands inside a microVM with hardware-level isolation — you just stop paying for the hypervisor underneath it.

Prerequisites

Prerequisite	Notes
A BoxLite Cloud account	Sign in to the console at `https://app.boxlite.ai`.
An API key	Created in the console — step 1 below.
Python 3, Node, or `curl` + `jq`	Whichever tab you follow in step 3.

Create an API key

In the console, open API Keys and click Create Key. Give it a name such as sdk-quickstart and leave Expires at its default of No expiration while you are exploring.The key looks like blk_live_... and is shown in full exactly once, at creation. Copy it then — the list view only ever shows a masked form afterwards. A key grants access to the Boxes API: it can create and manage boxes, and shared Linux base images are available to it automatically.For key rotation, per-environment keys, and the CLI credential store, see API keys and authentication.

Install the SDK or CLI

Python
Node
CLI
REST (curl)

pip install boxlite

npm install @boxlite-ai/boxlite tsx

The Node client construction for Cloud is shown in Give the key to your code.

curl -fsSL https://sh.boxlite.ai | sh

# The REST tab needs no SDK — only curl and jq
curl --version
jq --version

Then export your credentials. Read the key interactively so it never lands in your shell history:

read -rs BOXLITE_API_KEY   # prompts without echoing; paste your blk_live_... key
export BOXLITE_API_KEY
export BOXLITE_REST_URL="https://app.boxlite.ai/api"

Create a box and run code in it

Python
Node
CLI
REST (curl)

# cloud_quickstart.py — create a box on BoxLite Cloud, run a command, tear it down
# Run: python cloud_quickstart.py
import asyncio
import os
import time

from boxlite import (
    ApiKeyCredential,
    Boxlite,
    BoxOptions,
    BoxliteRestOptions,
)

api_key = os.environ.get("BOXLITE_API_KEY")
if not api_key:
    raise SystemExit("Set BOXLITE_API_KEY to your blk_live_... key before running this.")


async def main() -> None:
    # Boxlite.rest(...) is a synchronous constructor; every runtime method below is awaited
    rt = Boxlite.rest(
        BoxliteRestOptions(
            url=os.environ.get("BOXLITE_REST_URL", "https://app.boxlite.ai/api"),
            credential=ApiKeyCredential(api_key),
        )
    )

    box = None
    try:
        # name is an argument of rt.create(), not a field of BoxOptions
        box = await rt.create(
            BoxOptions(image="ghcr.io/boxlite-ai/boxlite-agent-base:v0.1.0"),
            name=f"sdk-quickstart-python-{int(time.time())}",
        )
        await box.start()
        print(f"Created box: {box.id}")

        # Over REST, exec takes the command plus an args list
        execution = await box.exec("echo", args=["Hello from BoxLite SDK"])

        output = ""
        async for line in execution.stdout():
            output += line

        result = await execution.wait()
        print(f"Exit code: {result.exit_code}")
        print(output)
    except Exception as exc:
        # Authentication failures, network errors and creation failures all surface here
        print(f"Cloud run failed: {exc!r}")
    finally:
        # Teardown lives on the runtime. Putting it in finally means a failure above
        # cannot leave a box running and billing.
        if box is not None:
            await rt.remove(box.id, force=True)
            print(f"Removed {box.id}")


if __name__ == "__main__":
    asyncio.run(main())

// cloud_quickstart.ts — create a box on BoxLite Cloud, run a command, tear it down
// Run: npx tsx cloud_quickstart.ts
import {
  ApiKeyCredential,
  BoxliteRestOptions,
  JsBoxlite,
} from "@boxlite-ai/boxlite";

async function main(): Promise<void> {
  const apiKey = process.env.BOXLITE_API_KEY;
  if (!apiKey) {
    throw new Error("Set BOXLITE_API_KEY to your blk_live_... key before running this.");
  }

  // JsBoxlite.rest(...) is a synchronous constructor; every runtime method below is awaited
  const rt = JsBoxlite.rest(
    new BoxliteRestOptions({
      url: process.env.BOXLITE_REST_URL ?? "https://app.boxlite.ai/api",
      credential: new ApiKeyCredential(apiKey),
    }),
  );

  let boxId: string | null = null;
  try {
    // The box name is the second argument of create(), not a field of the options object
    const box = await rt.create(
      { image: "ghcr.io/boxlite-ai/boxlite-agent-base:v0.1.0" },
      `sdk-quickstart-node-${Math.floor(Date.now() / 1000)}`,
    );
    boxId = box.id;
    await box.start();
    console.log(`Created box: ${box.id}`);

    // Over REST, exec takes the command plus an args array
    const execution = await box.exec("echo", ["Hello from BoxLite SDK"]);

    // A stream is consumed once; iterate until next() returns null
    const stdout = await execution.stdout();
    let output = "";
    while (true) {
      const line = await stdout.next();
      if (line === null) break;
      output += line;
    }

    const result = await execution.wait();
    console.log(`Exit code: ${result.exitCode}`);
    console.log(output);
  } catch (err) {
    // Authentication failures, network errors and creation failures all surface here
    console.error("Cloud run failed:", err);
  } finally {
    // Teardown lives on the runtime, so a failure above cannot leave a box running
    if (boxId !== null) {
      await rt.remove(boxId, true);
      console.log(`Removed ${boxId}`);
    }
    rt.close();
  }
}

main();

Two shapes differ from Python: exec takes its argument list positionally (box.exec("echo", ["hi"])), and a stdout stream is pulled with next() until it returns null rather than iterated with for await. Field names are camelCase throughout — result.exitCode, and diskSizeGb / memoryMib on the options object.

# One disposable box, one command, automatic teardown.
# --rm removes the box once the command exits.
boxlite run --rm --name "sdk-quickstart-cli-$(date +%s)" \
  ghcr.io/boxlite-ai/boxlite-agent-base:v0.1.0 \
  echo "Hello from BoxLite CLI"

boxlite talks to Cloud whenever REST configuration is present in the environment, which the BOXLITE_REST_URL and BOXLITE_API_KEY exports from step 2 provide. The CLI exit code is the exit code of the command you ran. To store credentials once instead of exporting them per shell, see API keys and authentication.

#!/usr/bin/env bash
# cloud_quickstart.sh — create a box on BoxLite Cloud, run a command, tear it down
set -euo pipefail

BOXLITE_REST_URL="${BOXLITE_REST_URL:-https://app.boxlite.ai/api}"
: "${BOXLITE_API_KEY:?Set BOXLITE_API_KEY to your blk_live_... key before running this}"

auth=(-H "Authorization: Bearer ${BOXLITE_API_KEY}")
json=(-H "Content-Type: application/json")
name="sdk-quickstart-rest-$(date +%s)"

# Create — the response carries the new box in the box_id field
box_id="$(curl -fsS -X POST "${BOXLITE_REST_URL}/v1/boxes" \
  "${auth[@]}" "${json[@]}" \
  -d "{\"name\":\"${name}\",\"image\":\"ghcr.io/boxlite-ai/boxlite-agent-base:v0.1.0\"}" \
  | jq -r '.box_id')"
echo "Created box: ${box_id}"

# Remove the box on any exit, so a failure below cannot leave it running
trap 'curl -fsS -X DELETE "${BOXLITE_REST_URL}/v1/boxes/${box_id}?force=true" "${auth[@]}" >/dev/null' EXIT

curl -fsS -X POST "${BOXLITE_REST_URL}/v1/boxes/${box_id}/start" "${auth[@]}"

# Exec — the response carries the execution in the execution_id field
exec_id="$(curl -fsS -X POST "${BOXLITE_REST_URL}/v1/boxes/${box_id}/exec" \
  "${auth[@]}" "${json[@]}" \
  -d '{"command":"echo","args":["Hello from BoxLite REST"]}' \
  | jq -r '.execution_id')"

# Read the execution record back
curl -fsS "${BOXLITE_REST_URL}/v1/boxes/${box_id}/executions/${exec_id}" "${auth[@]}"

Run it with bash cloud_quickstart.sh. Every path is relative to BOXLITE_REST_URL, so the create call above resolves to https://app.boxlite.ai/api/v1/boxes.

What just happened

The five calls in that script are the whole Cloud lifecycle. Every language binding and the REST API expose the same five, in the same order:

Authenticate. Boxlite.rest(...) wraps your key in an ApiKeyCredential and points every later call at https://app.boxlite.ai/api. Nothing is sent at construction time — the object is just a configured client.
Create. rt.create(BoxOptions(image=...), name=...) allocates a box from a shared Linux base image and returns a handle. The box exists but is not running.
Start. box.start() boots the microVM. Only now is there a kernel and a filesystem to run against.
Exec. box.exec("echo", args=[...]) launches one process inside the VM and hands you an execution handle. execution.wait() blocks until that process exits and returns its exit code.
Remove. rt.remove(box.id, force=True) destroys the box and its disk. Removal is a runtime method, not a box method — the box handle you hold is a pointer, and the runtime owns the fleet.

Step 5 is the one to internalize. A box you forget to remove keeps running, and a running box is what BoxLite Cloud charges for — see Plans, wallet, and usage. Putting teardown in a finally block, as the script above does, is the difference between an exception costing you a stack trace and an exception costing you a box.

Expected output

Created box: <box-id>
Exit code: 0
Hello from BoxLite SDK
Removed <box-id>

The Exit code line comes from execution.wait() and is the authoritative success signal. The Hello from BoxLite SDK line is what the box wrote to stdout, collected by iterating execution.stdout().

Troubleshooting

Symptom	Cause	Fix
`401 Unauthorized` on the first call	The key is missing, mistyped, or was deleted in the console.	Confirm the value starts with `blk_live_` and matches a live key in API Keys. See API keys and authentication.
`SystemExit: Set BOXLITE_API_KEY ...`, or the CLI uses your local runtime instead of Cloud	The key never reached the process — a new shell, a different terminal tab, or a service manager that does not inherit your exports.	Re-run the `read -rs` and `export` pair from step 2 in that shell. For anything long-lived, store the credential with `boxlite auth login` instead of exporting it.
A box from an earlier run is still listed as running	The script exited before teardown — an exception outside `try`, a `Ctrl-C`, or a crash.	Remove it explicitly with `await rt.remove("<BOX_ID_OR_NAME>", force=True)` (CLI: `boxlite rm`), then move teardown into a `finally` block as shown above.
A long job stops part-way through with no error from your code	The box was stopped for being idle, and work running inside the box does not count as activity.	Adjust STOP WHEN IDLE when you create the box in the console — see Stop when idle.
`execution.stdout()` finishes without yielding lines	Streamed output is a separate channel from the exit code. Only `execution.wait()` is guaranteed to report the process result.	Treat `result.exit_code` as the success signal and collect output as a bonus. When you need output you can depend on, redirect it to a file in the box and read the file back.
`404 Not Found` on every request	The base URL is wrong — most often the `/api` suffix is missing.	Set `BOXLITE_REST_URL` to exactly `https://app.boxlite.ai/api`.

Next steps

Boxes

Pick an image and a size, and learn the three lifecycle controls Cloud applies while a box runs.

Volumes

Storage that outlives a box, so the next box can mount it and read the data back.

Plans, wallet, and usage

What a running box costs against your included quota and wallet, plus the per-box ceilings.

Cloud vs open source

Every difference between a self-hosted box and a Cloud box, in one table.

​Prerequisites

​What just happened

​Expected output

​Troubleshooting

​Next steps