Use git to parse root of repo

README.md

@@ -31,6 +31,28 @@ See `nix/ci/default.nix` for action configuration in `nix`. This is turned by th
 `pre-commit` hook, or by running `nix run .#render-workflows`, into the workflow file
 in `.github/workflows/main.yaml`.
 
+### Advanced: control relative path with `--no-prepend-git-root`
+
+By default, workflow files will be rendered relative to the git repo root. To write workflow files relative to the process working directory (CWD), run:
+
+```
+nix run .#render-workflows -- --no-prepend-git-root
+```
+
+This is useful when you want files output somewhere *other* than the git root (e.g., when scripting or testing in a subdirectory).
+
+#### Passing the flag in pre-commit configuration
+
+If you need to add arguments (such as `--no-prepend-git-root`) to the pre-commit hook invocation, you can do so, e.g., using the `raw.args` option in your Nix flake configuration:
+
+```nix
+pre-commit.settings.hooks.render-actions = {
+  raw.args = [
+    "--no-prepend-git-root"
+  ];
+};
+```
+
 ## Installation
 
 This project uses `flake-parts`. You need to add the module exposed by this
@@ -107,3 +129,29 @@ The aim is to be minimal and allow free-form configuration by users instead of
 trying to generate it using logic in this project. Main purpose of this project
 is to enable writing action logic in `nix` rather than `yaml`. The
 opportunities opened by using `nix` are then mainly left for users to exploit.
+
+## Development
+
+**Format code:**
+
+```sh
+nix develop -c pre-commit run --all-files
+```
+
+**Check flake and evaluate tests:**
+
+```sh
+nix flake check
+```
+
+**Test workflow rendering locally:**
+
+```sh
+nix run .#render-workflows
+```
+
+**Check past commit conventions:**
+
+```sh
+git log --oneline
+```

nix/flake-modules/actions-nix/default.nix

@@ -44,6 +44,9 @@ _localFlake:
             entry =
               let
                 renderCI = self'.packages.render-workflows;
+                # To override the default behavior of outputting workflow files at the git repo root, pass
+                #   --no-prepend-git-root
+                # to this script; this will cause workflow files to be written relative to the process working directory instead.
               in
               "${renderCI}/bin/render-workflows";
           };
@@ -53,6 +56,7 @@ _localFlake:
         packages.render-workflows =
           (pkgs.writeShellApplication {
             name = "render-workflows";
+            runtimeInputs = [ pkgs.git ];
             text =
               let
                 pythonEnv = pkgs.python3.withPackages (p: [ p.pyyaml ]);

nix/flake-modules/actions-nix/render.py

@@ -37,7 +37,18 @@ def yaml_multiline_string_pipe(dumper, data):
 
 yaml.add_representer(str, yaml_multiline_string_pipe)
 
-def main(evaluated_ci_path: Optional[Path]):
+def get_git_toplevel() -> Path:
+    result = subprocess.run(
+        ["git", "rev-parse", "--show-toplevel"],
+        text=True,
+        capture_output=True,
+        check=True,
+    )
+    return Path(result.stdout.strip())
+
+def main(evaluated_ci_path: Optional[Path], prepend_git_root: bool = True):
+    git_toplevel = get_git_toplevel() if prepend_git_root else None
+
     if evaluated_ci_path is None:
         eval_process = partial(
             subprocess.run,
@@ -58,7 +69,10 @@ def main(evaluated_ci_path: Optional[Path]):
         workflows = json.loads(evaluated_ci_path.read_text())
 
     for key, value in workflows.items():
-        render_path = Path(key)
+        if prepend_git_root:
+            render_path = git_toplevel / key
+        else:
+            render_path = Path(key)
         render_path.parent.mkdir(exist_ok=True, parents=True)
         print(f"Writing to {render_path}")
         header = f"""# This file was autogenerated by actions.nix. Do not edit it manually.
@@ -73,5 +87,14 @@ def main(evaluated_ci_path: Optional[Path]):
 if __name__ == "__main__":
     argparser = argparse.ArgumentParser()
     argparser.add_argument("--evaluated-ci-path", required=False)
+    argparser.add_argument(
+        "--no-prepend-git-root",
+        action="store_true",
+        help="Do not prepend the git repo root to workflow paths"
+    )
     args = argparser.parse_args()
-    main(evaluated_ci_path=Path(args.evaluated_ci_path))
+    main(
+        evaluated_ci_path=Path(args.evaluated_ci_path) if args.evaluated_ci_path else None,
+        prepend_git_root=not args.no_prepend_git_root,
+    )
+