nix: add updater for partftpy

contrib/package/nix/partftpy/default.nix

@@ -4,15 +4,17 @@
   fetchurl,
   setuptools,
 }:
+let
+  pinData = lib.importJSON ./pin.json;
+in
 
 buildPythonPackage rec {
   pname = "partftpy";
-  version = "0.4.0";
+  inherit (pinData) version;
   pyproject = true;
 
   src = fetchurl {
-    url = "https://github.com/9001/partftpy/releases/download/v0.4.0/partftpy-0.4.0.tar.gz";
-    hash = "sha256-5Q2zyuJ892PGZmb+YXg0ZPW/DK8RDL1uE0j5HPd4We0=";
+    inherit (pinData) url hash;
   };
 
   build-system = [ setuptools ];

contrib/package/nix/partftpy/pin.json

@@ -0,0 +1,5 @@
+{
+    "url": "https://github.com/9001/partftpy/releases/download/v0.4.0/partftpy-0.4.0.tar.gz",
+    "version": "0.4.0",
+    "hash": "sha256-5Q2zyuJ892PGZmb+YXg0ZPW/DK8RDL1uE0j5HPd4We0="
+}

contrib/package/nix/partftpy/update.py

@@ -0,0 +1,50 @@
+#!/usr/bin/env python3
+
+# Update the Nix package pin
+#
+# Usage: ./update.sh
+
+import base64
+import json
+import hashlib
+import sys
+from pathlib import Path
+
+OUTPUT_FILE = Path("pin.json")
+TARGET_ASSET = lambda version: f"partftpy-{version}.tar.gz"
+HASH_TYPE = "sha256"
+LATEST_RELEASE_URL = "https://api.github.com/repos/9001/partftpy/releases/latest"
+
+
+def get_formatted_hash(binary):
+    hasher = hashlib.new("sha256")
+    hasher.update(binary)
+    asset_hash = hasher.digest()
+    encoded_hash = base64.b64encode(asset_hash).decode("ascii")
+    return f"{HASH_TYPE}-{encoded_hash}"
+
+
+def remote_release_pin():
+    import requests
+
+    response = requests.get(LATEST_RELEASE_URL).json()
+    version = response["tag_name"].lstrip("v")
+    asset_info = [a for a in response["assets"] if a["name"] == TARGET_ASSET(version)][0]
+    download_url = asset_info["browser_download_url"]
+    asset = requests.get(download_url)
+    formatted_hash = get_formatted_hash(asset.content)
+
+    result = {"url": download_url, "version": version, "hash": formatted_hash}
+    return result
+
+
+def main():
+    result = remote_release_pin()
+
+    print(result)
+    json_result = json.dumps(result, indent=4)
+    OUTPUT_FILE.write_text(json_result)
+
+
+if __name__ == "__main__":
+    main()