Add exec-sandbox deployment (self-hosted QEMU microVMs)

[clemlesne]

Add exec-sandbox deployment (self-hosted QEMU microVMs)

Summary

Proposing exec-sandbox as a new AbstractDeployment backend for SWE-ReX. It runs code in ephemeral QEMU microVMs with hardware-level isolation (KVM on Linux, HVF on macOS) — self-hosted, no cloud account needed.

Why

• Self-hosted — ModalDeployment and FargateDeployment require cloud accounts. DockerDeployment requires Docker. exec-sandbox runs on bare metal with just QEMU. Data never leaves the machine.
• macOS + Linux — HVF on macOS, KVM on Linux. Docker alternative for macOS dev machines without Docker Desktop.
• Fast — ~1-2ms from warm pool, ~200ms from memory snapshots.
• VM isolation — Hardware-level boundary vs Docker process isolation.
• Apache-2.0

How it maps

exec-sandbox is a Python library with an async API. Following the Daytona deployment pattern (PR #191):

class ExecSandboxDeploymentConfig(BaseModel):
    type: Literal["exec_sandbox"] = "exec_sandbox"
    language: str = "raw"
    memory_mb: int = 512

    def get_deployment(self) -> AbstractDeployment:
        from .exec_sandbox import ExecSandboxDeployment
        return ExecSandboxDeployment.from_config(self)

The deployment would:

1. start() — Boot a QEMU microVM via Scheduler.session(), then start the swerex-remote server inside it via session.exec()
2. stop() — Close the session (VM is ephemeral, auto-destroyed)
3. runtime — Return a RemoteRuntime connected to the swerex-remote server inside the VM
4. is_alive() — Check VM + runtime health

The key question is how to expose the swerex-remote HTTP server running inside the VM. exec-sandbox supports port forwarding via expose_ports, which could map the server port to the host.

Open questions

• Port forwarding — swerex-remote needs an HTTP endpoint reachable from the host. exec-sandbox's expose_ports feature can handle this, but the exact wiring needs validation.
• Base image — The swerex-remote binary would need to be available inside the VM. Options: pre-bake it into the QEMU image, or pip install at session start.

Links

• Repo · PyPI
• Reference PR: feat: add daytona deployment #191 (Daytona deployment — same integration pattern)

Happy to submit a PR if there's interest.