Monty

Pydantic Monty runs a subset of Python, written in Rust, inside the Mirage process. A run starts in microseconds. It has no host files, environment or network: the files it opens are the workspace’s, under the same mount modes and permissions as shell commands. It is the default python3 in both SDKs, in Node and in browsers.

Installation

Python
TypeScript

pip install 'mirage-ai[monty]'

pnpm add @pydantic/monty

Usage

Monty is in the default runtimes, so python3 works with no setup. To list it yourself:

Python
TypeScript
YAML

from mirage import RAMVFS, MountMode, Workspace

ws = Workspace({"/data": RAMVFS()}, mode=MountMode.EXEC, runtimes=["monty"])
await ws.shell("python3 -c 'print(1 + 1)'")

import { MountMode, RAMVFS, Workspace } from '@struktoai/mirage-node'

const ws = new Workspace({ '/data': new RAMVFS() }, { mode: MountMode.EXEC, runtimes: ['monty'] })
await ws.shell("python3 -c 'print(1 + 1)'")

mode: exec
runtimes:
  - monty
mounts:
  /data:
    vfs: ram

What is wired

Monty implements part of Python; see Python subset. For files, processes and the environment:

Python	Supported	Notes
`open()` with `r`, `w`, `a`, plus `b`	Yes
`open()` with `x` or `+`	No
`f.read()`, `f.readline()`, `f.readlines()`, `f.seek()`, `f.tell()`	Yes	The whole file is read at once.
`f.write()`	Yes	Each call is written at once.
`for line in f`, `f.truncate()`, `f.fileno()`	No
`Path.open`, `read_text`, `read_bytes`, `write_text`, `write_bytes`	Yes
`os.stat`, `Path.stat`, `exists`, `is_file`, `is_dir`, `is_symlink`	Yes	In TypeScript, use the named fields (`st.st_size`), not `st[6]`.
`os.lstat`, `os.fstat`	No
`os.listdir`, `Path.iterdir`	Yes
`os.scandir`, `os.walk`, `Path.glob`, `Path.rglob`	No
`os.mkdir`, `os.makedirs`, `Path.mkdir`	Yes
`os.rmdir`, `Path.rmdir`, `os.remove`, `os.unlink`, `Path.unlink`	Yes
`os.rename`, `os.replace`, `Path.rename`	Yes	Raises `OSError` across mounts.
`os.getcwd`, `Path.cwd`, `Path.resolve`	Yes	The shell’s working directory.
`os.chdir`	Python SDK	Lasts for the run. Raises `RuntimeError` in TypeScript.
`os.environ`, `os.getenv`	Yes	The session’s environment, never the host’s.
`argv`, `stdin` globals	Yes	The words after the script, and the piped input.
`sys.argv`, `sys.stdin`	No	Use `argv` and `stdin`.
`os.urandom`	Yes	Up to 1 MiB per call.
`os.path`	No
`os.open` and file descriptors, `os.truncate`	No
`os.symlink`, `os.readlink`, `os.link`	No
`os.utime`, `os.chmod`, `Path.touch`, `os.getxattr`	No
`json.load`, `json.dump`	No	Use `json.loads(f.read())` and `f.write(json.dumps(value))`.
`glob`, `shutil`, `subprocess`, `socket`	No	Importing one fails.

Notes

A run starts in the shell’s working directory. The script and every relative path pass the same mount and permission checks as cat: a rule protecting /data/job.py refuses python3 job.py from /data.
The words after the script are its argv as typed, with globs expanded as bash expands them. A word naming another mount is only a string.
A console session takes the working directory on its first input and keeps its own after that.
__file__ is the script’s name under the starting directory.

Python subset

Monty 1.0.0 implements a subset of Python, and Mirage never falls back to another interpreter.

Stdlib: asyncio, base64, binascii, collections, copy, dataclasses, datetime, functools, itertools, json, math, os, pathlib, random, re, sys, time, typing, unicodedata, each partial. No third-party imports.
Syntax: no class inheritance, metaclasses, classmethod, staticmethod, property or yield. Plain classes, function decorators, with, f-strings and comprehensions work.
Introspection: no dir (use hasattr), vars, globals, help, callable, issubclass, super, compile or __dict__.

Getting Started

Access

Policy

Learn

Integration

Help

VFS

CLIs

Runtimes

Installation

Usage

What is wired

Notes

Python subset

​Installation

​Usage

​What is wired

​Notes

​Python subset

Installation

Usage

What is wired

Notes

Python subset