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Quickstart (Zero-Config in 60s)

Launch a clean standalone cloud development sandbox with zero external configuration beyond the standard Modal CLI.

Launching Your First Sandbox

Run the modal-sandbox CLI with a chosen sandbox name:

modal-sandbox --name my-first-sandbox

Upon execution, the runner performs the following steps automatically:

  1. Builds / Caches Image Layers: Reuses prebaked Ubuntu images with Python 3.11, OpenSSH, and developer utilities.
  2. Generates SSH Keys: Configures an OpenSSH server on port 2222 inside the container and injects your connection profile into ~/.ssh/config.
  3. Starts Ingress Tunnel: Establishes a Cloudflare Tunnel forwarding port 3000 to the web.
  4. Initializes Workspace: Sets up /root/my-first-sandbox with an empty Git repository and default Python virtual environment.

Output resembles:

Provisioning Modal Sandbox: my-first-sandbox...
SSH configured: ssh my-first-sandbox
Web Ingress: https://<tunnel-id>.trycloudflare.com -> port 3000
Sandbox running (ID: sb-xxxxxxxx)

Connecting via SSH

You can connect directly using the alias written to ~/.ssh/config:

ssh my-first-sandbox

Or connect via the Modal CLI's native interactive shell:

modal shell <sandbox-id>

Testing Web Ingress

Every sandbox includes a web ingress tunnel routed to container port 3000. Test it by starting a simple HTTP server inside the sandbox:

ssh my-first-sandbox "python3 -m http.server 3000 --directory /root/my-first-sandbox"

Open the printed trycloudflare.com URL in your browser to view your sandbox files served live over HTTPS.

Next Steps