DEV Community

Arun Raghunath
Arun Raghunath

Posted on

pip install jhansi — the SDK is live

#api #python #showdev #tooling

Six weeks ago, running code on jhansi.io meant curl + sandbox IDs + manual cleanup.

Today it looks like this:

from jhansi import Sandbox

with Sandbox(language="python") as sb:
    sb.upload_file("main.py")
    result = sb.exec("python main.py")
    print(result["output"])
Enter fullscreen mode Exit fullscreen mode

That's the milestone. The SDK is live.

Why this matters

The API was always there. Petri — the execution engine underneath — has been running code in isolated Docker containers since v0.1. But you had to understand HTTP, manage container lifecycle, and remember to delete sandboxes or you'd leak resources.

The SDK removes all of that. You write Python. jhansi.io handles the rest.

The context manager was non-negotiable

If you create a sandbox and forget to delete it, you leak containers and workspace storage. That's not acceptable — especially when AI agents are creating sandboxes programmatically.

The context manager makes cleanup automatic:

with Sandbox(language="python") as sb:
    # sandbox created here
    sb.upload_file("main.py")
    result = sb.exec("python main.py")
# sandbox deleted here — even if exec raised an exception
Enter fullscreen mode Exit fullscreen mode

No leaked containers. No cleanup code. No surprises.

The Docker-in-Docker problem

Self-hosting Petri via docker compose up uncovered something we hadn't anticipated.

Petri runs inside a Docker container. But Petri's job is to spin up Docker containers to run your code. So Petri needs access to Docker — from inside Docker.

Fix one: mount the Docker socket.

volumes:
  - /var/run/docker.sock:/var/run/docker.sock
Enter fullscreen mode Exit fullscreen mode

Fix two: shared workspace path. Petri creates workspace folders inside its container. When it mounts those into sandbox containers, Docker looks for the path on the host — not inside Petri. The path doesn't exist.

volumes:
  - /var/run/docker.sock:/var/run/docker.sock
  - /tmp/petri-workspaces:/tmp/petri-workspaces
environment:
  - PETRI_WORKSPACE_ROOT=/tmp/petri-workspaces
Enter fullscreen mode Exit fullscreen mode

Same path both sides. Docker finds it. Problem solved.

Getting started 

# Start Petri
git clone https://github.com/jhansi-io/petri.git
cd petri
docker compose up

# Install the SDK
pip install jhansi
Enter fullscreen mode Exit fullscreen mode

Full docs at docs.jhansi.io.

What's next

  • v0.6 — persistent registry so sandboxes survive Petri restarts
  • v0.7 — streaming exec, real-time output as your code runs
  • MCP server — Cursor and Claude Code use Petri directly instead of their own cloud.

The MCP server is the one I'm most excited about. More on that soon.

Star the repo if you're following the build. ⭐
github.com/jhansi-io/jhansi

Top comments (0)