fcvm for Python

A client for the HTTP API of fcvm, which runs disposable, isolated Firecracker microVMs with container ergonomics. Use it to give an agent framework, a test harness or a build pipeline real VM sandboxes: create one from any OCI image, run commands, move files, snapshot it and fork running copies in about 150 ms.

The client has no dependencies and needs Python 3.9 or newer. The VMs run on a Linux host with KVM where fcvm is installed; the client itself runs anywhere that can reach that host's API.

pip install fcvm

from fcvm import Client

c = Client()
with c.create("box", template="python-sandbox", ttl="1h") as sb:      # removed when the block ends
    out = sb.run("pip install -q requests && python -c 'import requests; print(requests.__version__)'")
    sb.write_file("/work/app.py", "print('hi')\n")
    print(sb.exec("python /work/app.py").stdout)                      # ExecResult: exit_code, stdout, stderr
    job = sb.exec("python -m http.server 8000", background=True)      # a Job
    port = sb.publish(8000)                                           # http://127.0.0.1:{port} on the host
    job.kill()

snap = c.sandbox("prepared").snapshot("ready")
forks = snap.fork("try", count=3)                                     # three running Sandbox objects

Client() finds the local fcvm service by itself. For another host, set FCVM_URL and FCVM_TOKEN. The token gives full control of fcvm, so treat it like an SSH key.

• All methods
• The HTTP API
• Installing fcvm

Apache License 2.0.