Multiple sandboxes

This example shows how to run multiple CoreWeave sandboxes in parallel using a session. A session applies shared defaults across the sandboxes and cleans them up automatically when the block exits. Use this pattern to coordinate work across several sandboxes without managing each lifecycle individually.

Choose authentication

These examples run on serverless capacity unless a section specifies CKS. Choose the credential for the account that owns your sandboxes. See Choose and get credentials to obtain a key or token. Run the installation commands in an active Python virtual environment. Save the Python code from your credential tab as sandbox_auth.py beside the Python scripts you run from this page. It stores the authentication choice, not your credential. The examples import AUTH from that file and pass it explicitly to each new sandbox or session.

Forge API key
CoreWeave API access token

Use your Forge API key through the SDK’s W&B authentication strategy:

uv pip install 'cwsandbox[wandb]>=1.14.2'
export WANDB_API_KEY="[WANDB-API-KEY]"

sandbox_auth.py

from cwsandbox import AuthStrategy

AUTH = AuthStrategy.WANDB

Use the token for your CoreWeave organization:

uv pip install 'cwsandbox>=1.14.2'
export CWSANDBOX_API_KEY="[API-ACCESS-TOKEN]"

sandbox_auth.py

from cwsandbox import AuthStrategy

AUTH = AuthStrategy.COREWEAVE_API_KEY

For CKS placement, choose the CoreWeave token, enable a runner, and set placement_mode="cks" on sandbox creation or in SandboxDefaults. Creating a session with auth=AUTH also authenticates the sandboxes it owns. Keep the same credential when reconnecting, listing, or cleaning up sandboxes.

Run sandboxes in a session

Sessions manage multiple sandboxes with shared defaults and automatic cleanup:

from sandbox_auth import AUTH
from cwsandbox import Sandbox, SandboxDefaults

defaults = SandboxDefaults(
    container_image="python:3.11",
    tags=("my-app",),
    resources={"cpu": "1", "memory": "1Gi"},
)

with Sandbox.session(defaults, auth=AUTH) as session:
    sb1 = session.sandbox()
    sb2 = session.sandbox()

    p1 = sb1.exec(["echo", "one"])
    p2 = sb2.exec(["echo", "two"])

    print(p1.result().stdout, p2.result().stdout)
# All sandboxes cleaned up

For sandbox pools, adoption patterns, and lifecycle management, see the Sessions guide.

Sandboxes

Use sandboxes

Manage sandboxes

Reference

Choose authentication

Run sandboxes in a session

​Choose authentication

​Run sandboxes in a session

Choose authentication

Run sandboxes in a session