Thunder Sandbox for Python

Create short-lived GPU sandboxes, run commands over SSH, and move files with a small, typed Python API.

Thunder Sandbox uses the same account and credentials as the Thunder CLI. It handles sandbox lifecycle, SSH key creation, readiness polling, command execution, uploads, and downloads without adding any runtime Python dependencies.

Installation

Thunder Sandbox requires Python 3.10 or newer and the system ssh, scp, and ssh-keygen executables.

pip install thunder-sandbox

To install the current development branch directly from GitHub:

pip install git+https://github.com/Thunder-Compute/thunder-sandbox.git

Authenticate with the Thunder CLI before using the library:

tnr login

Alternatively, set TNR_API_TOKEN and, when using a non-default API endpoint, TNR_API_URL.

Quick start

import thunder_sandbox as thunder

sandbox = thunder.Sandbox.create(
    cpu=4,
    memory=32,
    storage=50,
    gpu_type=thunder.GPUType.A6000,
    gpu_count=1,
    timeout=900,
)

try:
    sandbox.wait_until_ready()

    process = sandbox.exec("nvidia-smi")
    stdout = process.stdout.read()
    exit_code = process.wait()
    if exit_code != 0:
        raise RuntimeError(process.stderr.read())
    print(stdout)
finally:
    sandbox.terminate()

Sandboxes are addressed by id. Sandbox.create() generates an Ed25519 key pair and stores it under ~/.thunder/sandbox_keys/<sandbox-id>. The public key is immutable for the lifetime of the sandbox.

A name is an optional label. It must be free of any other live sandbox in the organization, and it is released once a sandbox finishes, so the same label can be reused later. A name never addresses a sandbox:

sandbox = thunder.Sandbox.create(name="training-run", gpu_type=thunder.GPUType.H100)
print(sandbox.id, sandbox.name)

# Claiming a name a live sandbox already holds raises ConflictError.
# Looking one up searches live sandboxes; prefer Sandbox.from_id.
same = thunder.Sandbox.from_name("training-run")

Handling errors

Conditions worth retrying are typed, so they can be caught without matching on message text. Each carries the API's code, the HTTP status, and the server's retry_after hint when one was sent:

try:
    sandbox = thunder.Sandbox.create(gpu_type=thunder.GPUType.H100)
except thunder.CapacityError as exc:
    # No free GPU of that type right now; the request was fine.
    time.sleep(exc.retry_after or 30)
except thunder.RetryableError:
    # Rate limited, or Thunder could not service the request.
    ...

Run commands

Pass command arguments separately to avoid local shell interpretation:

process = sandbox.exec("python3", "-c", "print('hello from Thunder')")
print(process.stdout.read())
exit_code = process.wait()

Commands can set a working directory, environment variables, a timeout, or a pseudo-terminal:

process = sandbox.exec(
    "python3",
    "train.py",
    workdir="/home/ubuntu/project",
    env={"MODEL": "llama", "DEBUG": "1"},
    timeout=600,
)

Transfer files

sandbox.upload("model.py", "/home/ubuntu/model.py")
sandbox.upload("dataset", "/home/ubuntu/dataset", recursive=True)

sandbox.download("/home/ubuntu/results.json", "results.json")
sandbox.download("/home/ubuntu/checkpoints", "checkpoints", recursive=True)

Network policies

Sandboxes have unrestricted outbound access by default. Restriction is always explicit:

# No outbound internet access.
closed = thunder.Sandbox.create(block_network=True)

# Only the specified CIDRs and domains are permitted.
restricted = thunder.Sandbox.create(
    outbound_cidr_allowlist=["203.0.113.0/24"],
    outbound_domain_allowlist=["pypi.org", "files.pythonhosted.org"],
)

CIDR and domain allowlists are independent. Supply both when restricted workloads need both direct IP and DNS-based access.

Environment and lifetime

sandbox = thunder.Sandbox.create(
    env={"EXPERIMENT": "baseline"},
    timeout=3600,
)

timeout is the sandbox lifetime in seconds. Set it to None to create a sandbox without an enforced TTL.

Work with existing sandboxes

with thunder.Client.from_cli() as client:
    for sandbox in client.list_sandboxes():
        print(sandbox.id, sandbox.status.value)

    sandbox = client.get_sandbox("sbx-0123456789abcdef")
    sandbox.wait_until_ready(timeout=300)
    print(" ".join(sandbox.ssh_command))

The private SSH key must still exist locally to execute commands or transfer files against an existing sandbox.

Async API

AsyncSandbox exposes the same lifecycle and remote-operation primitives for async applications:

import asyncio
import thunder_sandbox as thunder


async def main() -> None:
    sandbox = await thunder.AsyncSandbox.create(
        gpu_type=thunder.GPUType.A6000,
        gpu_count=1,
    )
    try:
        await sandbox.wait_until_ready()
        process = await sandbox.exec("nvidia-smi")
        exit_code = await process.wait()
        if exit_code != 0:
            raise RuntimeError(process.stderr.read())
        print(process.stdout.read())
    finally:
        await sandbox.terminate()


asyncio.run(main())

Configuration

Configuration is resolved from the following sources:

1. Explicit ClientConfig values.
2. TNR_API_TOKEN and TNR_API_URL environment variables.
3. Thunder CLI state in ~/.thunder/cli_config.json.
4. The default Thunder API endpoint.

Set TNR_HOME to use a different directory for CLI state and sandbox SSH keys.

License

Thunder Sandbox is available under the Apache License 2.0.