Check nixos installer for missing deps

check-missing-deps.py

import functools
import json
import os.path
import subprocess
import sys


@functools.lru_cache(None)
def _get_drv_info(drv):
    raw = subprocess.check_output([
        "nix",
        "--extra-experimental-features",
        "nix-command",
        "derivation",
        "show",
        drv + "^*",
    ]).decode()
    return json.loads(raw)[drv]


def get_output_path(drv, name):
    info = _get_drv_info(drv)
    return info["outputs"][name]["path"], "hash" in info["outputs"][name]


def get_inputs(drv):
    info = _get_drv_info(drv)
    for drv, data in info["inputDrvs"].items():
        for output in data["outputs"]:
            yield drv, output


@functools.lru_cache(None)
def missing_dep_chain(drv, output):
    path, is_fixed = get_output_path(drv, output)

    # if the path exists, we don't need to build OR fetch it
    if os.path.exists(path):
        return []

    # if the path does not exist and is an FOD, give up immediately
    if is_fixed:
        return [path]

    for ref in get_inputs(drv):
        if chain := missing_dep_chain(*ref):
            return [path] + chain

    return []


def main():
    for item in missing_dep_chain(sys.argv[1], "out"):
        print(item)

if __name__ == '__main__':
    main()