@computesdk/lelantos

Lelantos provider for ComputeSDK — execute code in secure, EU-native Firecracker microVM sandboxes with full filesystem and terminal support.

Lelantos is an E2B-API-compatible sandbox platform running on Hetzner bare-metal in the EU. Because the wire protocol is E2B-compatible, this provider wraps the same e2b npm SDK — but points it at a Lelantos control plane via domain / apiUrl and threads those options through every SDK call (create, connect, list, kill, snapshot, template), so lifecycle operations stay on Lelantos rather than falling back to api.e2b.app.

Installation

npm install @computesdk/lelantos

Setup

1. Get your Lelantos API key from lelantos.ai
2. Set the environment variable:

export LELANTOS_API_KEY=lel_your_api_key_here

Lelantos issues lel_… keys. The provider accepts both the lel_… and e2b_… forms of a Lelantos key: a native lel_<hex> key is transparently presented to the underlying e2b SDK as its e2b_<hex> alias (the e2b SDK validates the key prefix client-side since v2.27), and the Lelantos control plane resolves both forms to the same key.

Quick Start

Configure compute with the Lelantos provider and create a sandbox:

import { compute } from 'computesdk';
import { lelantos } from '@computesdk/lelantos';

compute.setConfig({
  provider: lelantos({ apiKey: process.env.LELANTOS_API_KEY }),
});

const sandbox = await compute.sandbox.create();

const result = await sandbox.runCommand(`python3 - <<'PY'
import platform
print("Hello from a Lelantos microVM")
print(platform.platform())
PY`);

console.log(result.stdout);
await sandbox.destroy();

Alternatively, call the provider factory directly when you only need one provider:

import { lelantos } from '@computesdk/lelantos';

const sdk = lelantos({ apiKey: process.env.LELANTOS_API_KEY });
const sandbox = await sdk.sandbox.create();

Configuration

Environment Variables

export LELANTOS_API_KEY=lel_your_api_key_here
# Optional — override the control-plane + sandbox domain (defaults to lelantos.ai)
export LELANTOS_DOMAIN=lelantos.ai
# Optional — explicit control-plane URL (overrides the domain-derived URL)
export LELANTOS_API_URL=https://api.lelantos.ai

The provider resolves credentials with the following fallback order so it is a drop-in for E2B-shaped configs:

• API key: config.apiKey → LELANTOS_API_KEY → E2B_API_KEY
• Domain: config.domain → LELANTOS_DOMAIN → E2B_DOMAIN
• API URL: config.apiUrl → LELANTOS_API_URL → E2B_API_URL

Configuration Options

interface LelantosConfig {
  /** Lelantos API key (lel_… or e2b_… form). Falls back to LELANTOS_API_KEY then E2B_API_KEY. */
  apiKey?: string;
  /** Control-plane + sandbox domain, e.g. 'lelantos.ai'. Falls back to LELANTOS_DOMAIN then E2B_DOMAIN. */
  domain?: string;
  /** Explicit control-plane URL override. Falls back to LELANTOS_API_URL then E2B_API_URL. */
  apiUrl?: string;
  /** Execution timeout in milliseconds */
  timeout?: number;
}

Pointing the provider at a self-hosted or staging Lelantos slot is just a matter of setting domain (and optionally apiUrl):

const provider = lelantos({
  apiKey: process.env.LELANTOS_API_KEY,
  domain: 'staging.lelantos.ai',
});

Features

• ✅ EU-native microVMs — Firecracker isolation on Hetzner bare-metal in the EU
• ✅ Command Execution — Run shell commands in the sandbox, with real exit codes surfaced (non-zero exits are returned, not masked)
• ✅ Filesystem Operations — Read, write, list, mkdir, exists, remove
• ✅ Per-port Preview URLs — getUrl({ port }) returns https://{port}-{sandboxId}.{domain}
• ✅ Snapshots & Templates — Snapshot a running sandbox; list/delete templates
• ✅ Domain / apiUrl threaded everywhere — control-plane calls always target your Lelantos slot

API Reference

Command Execution

// Run Python via heredoc
const result = await sandbox.runCommand(`python3 - <<'PY'
import json
print(json.dumps({"message": "Hello from Python"}))
PY`);

// List files
const ls = await sandbox.runCommand('ls -la');

// A non-zero exit is returned (not thrown) with the real exit code + stderr
const failed = await sandbox.runCommand('exit 3');
console.log(failed.exitCode); // 3

Filesystem Operations

await sandbox.filesystem.writeFile('/tmp/hello.py', 'print("Hello World")');
const content = await sandbox.filesystem.readFile('/tmp/hello.py');
await sandbox.filesystem.mkdir('/tmp/data');
const files = await sandbox.filesystem.readdir('/tmp');
const exists = await sandbox.filesystem.exists('/tmp/hello.py');
await sandbox.filesystem.remove('/tmp/hello.py');

Preview URLs

// Expose a server running on port 3000 inside the sandbox
const url = await sandbox.getUrl({ port: 3000 });
// => https://3000-<sandboxId>.lelantos.ai

Sandbox Management

const info = await sandbox.getInfo();
console.log(info.id, info.status, info.createdAt);

await sandbox.destroy();

Error Handling

import { lelantos } from '@computesdk/lelantos';

try {
  const compute = lelantos({ apiKey: process.env.LELANTOS_API_KEY });
  const sandbox = await compute.sandbox.create();
} catch (error) {
  if (error.message.includes('Missing Lelantos API key')) {
    console.error('Set LELANTOS_API_KEY environment variable');
  } else if (error.message.includes('authentication failed')) {
    console.error('Check your Lelantos API key');
  } else if (error.message.includes('quota exceeded')) {
    console.error('Lelantos usage limits reached');
  }
}

Best Practices

1. Resource Management — Always destroy sandboxes when done to free resources.
2. Error Handling — Use try/catch around create/connect calls.
3. Timeouts — Set an appropriate timeout for long-running tasks.
4. API Key Security — Never commit API keys to version control.

Limitations

• Template creation — Build templates via the E2B-compatible template build protocol / CLI, or snapshot a running sandbox with snapshot.create(). Direct template.create() is intentionally unsupported.
• Region — Sandboxes run in the EU (single-region today).

Roadmap

Lelantos also offers browser sandboxes (CDP-controllable Firecracker browser microVMs). A follow-up release will add a Lelantos-only browser extension namespace to this provider. This initial package is intentionally compute-focused (portable sandbox / snapshot / template surface only) to keep it a clean drop-in alongside the other ComputeSDK providers.

Support

• Lelantos
• ComputeSDK Issues

License

MIT