update-python-libraries: make hermetic (#395046)

pkgs/by-name/up/update-python-libraries/package.nix

@@ -1,4 +1,5 @@
 {
+  lib,
   python3,
   runCommand,
   git,
@@ -9,8 +10,6 @@
 runCommand "update-python-libraries"
   {
     buildInputs = [
-      nix
-      nix-prefetch-git
       (python3.withPackages (
         ps: with ps; [
           packaging
@@ -18,11 +17,14 @@ runCommand "update-python-libraries"
           toolz
         ]
       ))
-      git
     ];
   }
   ''
     cp ${./update-python-libraries.py} $out
     patchShebangs $out
-    substituteInPlace $out --replace 'GIT = "git"' 'GIT = "${git}/bin/git"'
+    substituteInPlace $out \
+      --replace-fail 'NIX = "nix"' 'NIX = "${lib.getExe nix}"' \
+      --replace-fail 'NIX_PREFETCH_URL = "nix-prefetch-url"' 'NIX_PREFETCH_URL = "${lib.getExe' nix "nix-prefetch-url"}"' \
+      --replace-fail 'NIX_PREFETCH_GIT = "nix-prefetch-git"' 'NIX_PREFETCH_GIT = "${lib.getExe nix-prefetch-git}"' \
+      --replace-fail 'GIT = "git"' 'GIT = "${lib.getExe git}"'
   ''

pkgs/by-name/up/update-python-libraries/update-python-libraries.py

@@ -36,10 +36,13 @@ PRERELEASES = False
 
 BULK_UPDATE = False
 
+NIX = "nix"
+NIX_PREFETCH_URL = "nix-prefetch-url"
+NIX_PREFETCH_GIT = "nix-prefetch-git"
 GIT = "git"
 
 NIXPKGS_ROOT = (
-    subprocess.check_output(["git", "rev-parse", "--show-toplevel"])
+    subprocess.check_output([GIT, "rev-parse", "--show-toplevel"])
     .decode("utf-8")
     .strip()
 )
@@ -79,7 +82,7 @@ def _get_attr_value(attr_path: str) -> Optional[Any]:
     try:
         response = subprocess.check_output(
             [
-                "nix",
+                NIX,
                 "--extra-experimental-features",
                 "nix-command",
                 "eval",
@@ -164,7 +167,7 @@ def _hash_to_sri(algorithm, value):
     return (
         subprocess.check_output(
             [
-                "nix",
+                NIX,
                 "--extra-experimental-features",
                 "nix-command",
                 "hash",
@@ -260,7 +263,7 @@ def _get_latest_version_github(attr_path, package, extension, current_version, t
     try:
         homepage = subprocess.check_output(
             [
-                "nix",
+                NIX,
                 "--extra-experimental-features",
                 "nix-command",
                 "eval",
@@ -301,7 +304,7 @@ def _get_latest_version_github(attr_path, package, extension, current_version, t
 
         algorithm = "sha256"
         cmd = [
-            "nix-prefetch-git",
+            NIX_PREFETCH_GIT,
             f"https://github.com/{owner}/{repo}.git",
             "--hash",
             algorithm,
@@ -317,7 +320,7 @@ def _get_latest_version_github(attr_path, package, extension, current_version, t
             hash = (
                 subprocess.check_output(
                     [
-                        "nix-prefetch-url",
+                        NIX_PREFETCH_URL,
                         "--type",
                         "sha256",
                         "--unpack",
@@ -336,7 +339,7 @@ def _get_latest_version_github(attr_path, package, extension, current_version, t
             try:
                 hash = (
                     subprocess.check_output(
-                        ["nix-prefetch-url", "--type", "sha256", "--unpack", tag_url],
+                        [NIX_PREFETCH_URL, "--type", "sha256", "--unpack", tag_url],
                         stderr=subprocess.DEVNULL,
                     )
                     .decode("utf-8")

pkgs/tools/package-management/nix-prefetch-scripts/default.nix

@@ -49,6 +49,7 @@ let
         description = "Script used to obtain source hashes for fetch${tool}";
         maintainers = with maintainers; [ bennofs ];
         platforms = platforms.unix;
+        mainProgram = "nix-prefetch-${tool}";
       };
     };
 in