nix-required-mounts: use wrappers instead of statically embedding config into the script

pkgs/by-name/ni/nix-required-mounts/main.py

@@ -1,3 +1,5 @@
+#!/usr/bin/env python3
+
 import glob
 import json
 import subprocess
@@ -6,16 +8,23 @@ from argparse import ArgumentParser
 from itertools import chain
 from pathlib import Path
 from sys import stderr
-from typing import List
+from typing import Dict, List, TypedDict
+
+
+class Pattern(TypedDict):
+    onFeatures: List[str]
+    paths: List[str]  # List of glob patterns
+
+
+class HookConfig(TypedDict):
+    nixExe: str
+    allowedPatterns: Dict[str, Pattern]
 
-CONFIG = {
-    "nixExe": "nix",
-    "allowedPatterns": {},
-}
 
 parser = ArgumentParser("pre-build-hook")
 parser.add_argument("derivation_path")
 parser.add_argument("sandbox_path", nargs="?")
+parser.add_argument("--config", type=Path)
 parser.add_argument(
     "--issue-command",
     choices=("always", "conditional", "never"),
@@ -39,12 +48,12 @@ def symlink_parents(p: Path) -> List[Path]:
 
 
 def entrypoint():
-    if __name__ != "__main__":
-        return
-
     args = parser.parse_args()
     drv_path = args.derivation_path
 
+    with open(args.config, "r") as f:
+        config = json.load(f)
+
     if not Path(drv_path).exists():
         print(
             f"[E] {drv_path} doesn't exist."
@@ -55,7 +64,7 @@ def entrypoint():
 
     proc = subprocess.run(
         [
-            CONFIG["nixExe"],
+            config["nixExe"],
             "show-derivation",
             drv_path,
         ],
@@ -78,7 +87,7 @@ def entrypoint():
         return
     [canon_drv_path] = drv.keys()
 
-    allowed_patterns = CONFIG["allowedPatterns"]
+    allowed_patterns = config["allowedPatterns"]
     known_features = set(
         chain.from_iterable(
             pattern["onFeatures"] for pattern in allowed_patterns.values()
@@ -92,7 +101,9 @@ def entrypoint():
 
     features = list(filter(known_features.__contains__, features))
 
-    patterns = list(chain.from_iterable(allowed_patterns[f]["paths"] for f in features))  # noqa: E501
+    patterns = list(
+        chain.from_iterable(allowed_patterns[f]["paths"] for f in features)
+    )  # noqa: E501
 
     roots = sorted(
         set(Path(path) for pattern in patterns for path in glob.glob(pattern))
@@ -115,4 +126,5 @@ def entrypoint():
         print()
 
 
-entrypoint()
+if __name__ == "__main__":
+    entrypoint()

pkgs/by-name/ni/nix-required-mounts/package.nix

@@ -16,42 +16,32 @@
 , formats
 , lib
 , nix
-, python3
+, python3Packages
+, makeWrapper
 , runCommand
 }:
 
 
 let
-  confPath = (formats.pythonVars { }).generate "config.py" {
-    CONFIG = {
-      inherit allowedPatterns;
-      nixExe = lib.getExe nix;
-    };
+  confPath = (formats.json { }).generate "config.py" {
+    inherit allowedPatterns;
+    nixExe = lib.getExe nix;
   };
   pname = "nix-required-mounts";
 in
 
 runCommand pname
 {
-  inherit confPath;
+  nativeBuildInputs = [
+    makeWrapper
+    python3Packages.wrapPython
+  ];
   meta.mainProgram = pname;
 } ''
   ${lib.getExe buildPackages.python3.pkgs.flake8} ${./main.py}
 
-  cat > main.py << EOF
-  #!${lib.getExe python3}
-
-  $(cat ${./main.py})
-  EOF
-
-  sed -ie '
-    /^entrypoint()$/ {
-      x ;
-      r ${confPath}
-      }' main.py
-
-  echo "entrypoint()" >> main.py
-
   mkdir -p $out/bin
-  install main.py $out/bin/${pname}
+  install ${./main.py} $out/bin/${pname}
+  wrapProgram $out/bin/${pname} --add-flags "--config ${confPath}"
+  wrapPythonPrograms
 ''