nix-update: add url parameter to override the repository discovery

README.md

@@ -118,6 +118,18 @@ In some cases this heurestic is wrong. One can override the behavior like that:
 $ nix-update hello --override-filename pkgs/applications/misc/hello/default.nix
 ```
 
+The `nix-update` command checks for new releases of a package using the `src`
+attribute. However, in some cases a package may use a non-standard release URL
+that is not supported by `nix-update`, but still has a repository with release
+information. For example, the Signal Desktop package in Nixpkgs fetches updates
+from https://updates.signal.org/, but also publishes release information on its
+GitHub page. In such cases, use the `--url` parameter to direct nix-update to
+the correct repository:
+
+``` console
+nix-update --url https://github.com/signalapp/Signal-Desktop --override-filename pkgs/applications/networking/instant-messengers/signal-desktop/default.nix   signal-desktop 
+```
+
 With the `--shell`, `--build`, `--test` and `--run` flags the update can be
 tested. Additionally, the `--review` flag can be used to
 initiate a run of [nixpkgs-review](https://github.com/Mic92/nixpkgs-review), which will ensure all

nix_update/__init__.py

@@ -40,6 +40,10 @@ def parse_args(args: list[str]) -> Options:
         action="store_true",
         help="Use passthru.updateScript instead if possible",
     )
+    parser.add_argument(
+        "--url",
+        help="URL to the repository to check for a release instead of using the URL in the src attribute of the package",
+    )
     parser.add_argument(
         "--write-commit-message",
         metavar="FILE",
@@ -89,6 +93,7 @@ def parse_args(args: list[str]) -> Options:
         build=a.build,
         commit=a.commit,
         use_update_script=a.use_update_script,
+        url=a.url,
         write_commit_message=a.write_commit_message,
         run=a.run,
         shell=a.shell,

nix_update/eval.py

@@ -132,6 +132,8 @@ def eval_attr(opts: Options) -> Package:
     package = Package(attribute=opts.attribute, **out)
     if opts.override_filename is not None:
         package.filename = opts.override_filename
+    if opts.url is not None:
+        package.parsed_url = urlparse(opts.url)
     if opts.version_preference != VersionPreference.SKIP and package.old_version == "":
         raise UpdateError(
             f"Nix's builtins.parseDrvName could not parse the version from {package.name}"

nix_update/options.py

@@ -14,6 +14,7 @@ class Options:
     version_regex: str = "(.*)"
     import_path: str = os.getcwd()
     override_filename: Optional[str] = None
+    url: Optional[str] = None
     commit: bool = False
     use_update_script: bool = False
     write_commit_message: Optional[str] = None