Fuse in Boxlite demo2

fuse_example.py

#!/usr/bin/env python3
"""Run a custom FUSE filesystem inside a BoxLite VM."""

import asyncio
from pathlib import Path

import boxlite

HERE = Path(__file__).parent


async def main():
    async with boxlite.SimpleBox(image="python:slim") as box:
        await box.copy_in(str(HERE / "hellofs.py"), "/opt")
        await box.copy_in(str(HERE / "run_fuse_demo.sh"), "/opt")

        result = await box.exec("sh", "/opt/run_fuse_demo.sh")

        print(result.stdout)


if __name__ == "__main__":
    asyncio.run(main())

hellofs.py

#!/usr/bin/env python3
"""Minimal FUSE filesystem: serves one read-only virtual file /hello.txt."""

import os
import sys
import stat
import errno

from fuse import FUSE, FuseOSError, Operations


class HelloFS(Operations):
    DATA = b"Hello from FUSE inside BoxLite!\n"

    def getattr(self, path, fh=None):
        if path == "/":
            return {"st_mode": stat.S_IFDIR | 0o755, "st_nlink": 2}
        if path == "/hello.txt":
            return {"st_mode": stat.S_IFREG | 0o444, "st_size": len(self.DATA)}
        raise FuseOSError(errno.ENOENT)

    def readdir(self, path, fh):
        return [".", "..", "hello.txt"]

    def read(self, path, size, offset, fh):
        return self.DATA[offset:offset + size]


if __name__ == "__main__":
    mountpoint = sys.argv[1] if len(sys.argv) > 1 else "/mnt/hello"
    os.makedirs(mountpoint, exist_ok=True)
    print(f"Mounting HelloFS at {mountpoint}", flush=True)
    FUSE(HelloFS(), mountpoint, foreground=True, nothreads=True)

run_fuse_demo.sh

#!/bin/sh
# Demo: install FUSE, mount a custom filesystem, read from it, cleanup.
set -e

# 1. Install FUSE + fusepy
apt-get update -qq > /dev/null 2>&1
apt-get install -y -qq fuse3 libfuse-dev > /dev/null 2>&1
pip install -q fusepy > /dev/null 2>&1

# 2. Ensure /dev/fuse exists (slim images may lack modprobe)
if [ ! -e /dev/fuse ]; then
    mknod /dev/fuse c 10 229
    chmod 666 /dev/fuse
fi

# 3. Mount the FUSE filesystem in background
SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
python3 "$SCRIPT_DIR/hellofs.py" /mnt/hello &
sleep 2

# 4. Demo: read from the virtual filesystem
echo "=== ls /mnt/hello ==="
ls -la /mnt/hello/
echo "=== cat /mnt/hello/hello.txt ==="
cat /mnt/hello/hello.txt
echo "=== mount info ==="
mount | grep hello

# 5. Cleanup
fusermount3 -u /mnt/hello
echo "done"