Process inside daemon immediately exits when using FIFO

I have a setup that looks roughly like the following example:

from contextlib import contextmanager
import subprocess
import os
from pathlib import Path

import daemon


@contextmanager
def tmp_fifo(path: Path):
    try:
        os.mkfifo(path)
        file = os.open(path, os.O_RDWR | os.O_NONBLOCK)
        yield file
    finally:
        os.unlink(path)


with tmp_fifo(Path.home() / "sh.fifo") as fifo, open("dout.log", "w+") as outfile:
    context = daemon.DaemonContext()
    with context:
        with subprocess.Popen(["sh"], stdin=fifo, stdout=outfile) as popen:
            popen.wait()

Essentially, what I am trying to do is to forward a shell to a FIFO. Without daemonizing, this works; i.e., I could write

from contextlib import contextmanager
import subprocess
import os
from pathlib import Path


@contextmanager
def tmp_fifo(path: Path):
    try:
        os.mkfifo(path)
        file = os.open(path, os.O_RDWR | os.O_NONBLOCK)
        yield file
    finally:
        os.unlink(path)


with tmp_fifo(Path.home() / "sh.fifo") as fifo, open("dout.log", "w+") as outfile:
    with subprocess.Popen(["sh"], stdin=fifo, stdout=outfile) as popen:
        popen.wait()

which allows me to input commands in the FIFO and see the results in the log file. How do I reproduce the desired behavior using a daemon? I tried moving the file redirects to the DaemonContext constructor, but that doesn't help. I also looked through the configuration options but none seem to be applicable.

You may need to try moving the FIFO and log file handling into the daemon context. Try something like the following:

from contextlib import contextmanager
import subprocess
import os
from pathlib import Path
import daemon

@contextmanager
def tmp_fifo(path: Path):
    try:
        os.mkfifo(path)
        file = os.open(path, os.O_RDWR | os.O_NONBLOCK)
        yield file
    finally:
        os.unlink(path)

def run_daemonized_shell():
    fifo_path = Path.home() / "sh.fifo"
    log_path = "dout.log"

    # Setup the daemon context FIRST
    with daemon.DaemonContext():
        with tmp_fifo(fifo_path) as fifo:
            with open(log_path, "w+") as outfile:
                with subprocess.Popen(["sh"], stdin=fifo, stdout=outfile) as popen:
                    popen.wait()

if __name__ == "__main__":
    run_daemonized_shell()