WIP

config/dev_autoreload.py

@@ -0,0 +1,112 @@
+from __future__ import annotations
+
+from pathlib import Path
+from typing import TYPE_CHECKING
+
+import django_watchfiles
+from django.utils import autoreload
+
+if TYPE_CHECKING:
+    from collections.abc import Iterable
+    from collections.abc import Sequence
+
+    from watchfiles import Change
+
+IGNORED_PROJECT_ROOT_NAMES: frozenset[str] = frozenset({
+    ".git",
+    ".venv",
+    "__pycache__",
+    "firecracker",
+})
+
+
+def _resolve_path(path: Path) -> Path:
+    try:
+        return path.resolve()
+    except OSError:
+        return path.absolute()
+
+
+def _is_relative_to(path: Path, parent: Path) -> bool:
+    try:
+        path.relative_to(parent)
+    except ValueError:
+        return False
+    return True
+
+
+def build_project_watch_roots(
+    project_root: Path,
+    *,
+    ignored_root_names: Sequence[str] = tuple(IGNORED_PROJECT_ROOT_NAMES),
+) -> tuple[Path, ...]:
+    """Return top-level project directories worth watching during development."""
+    ignored_names = set(ignored_root_names)
+    resolved_project_root = _resolve_path(project_root)
+    return tuple(
+        sorted(
+            _resolve_path(child)
+            for child in resolved_project_root.iterdir()
+            if child.is_dir() and not child.name.startswith(".") and child.name not in ignored_names
+        ),
+    )
+
+
+class TussilagoWatchfilesReloader(django_watchfiles.WatchfilesReloader):
+    """Use child directories instead of repo root for dev autoreload watches."""
+
+    def __init__(
+        self,
+        *,
+        project_root: Path,
+        ignored_paths: Sequence[Path] | None = None,
+    ) -> None:
+        """Store project-specific watch settings before watcher startup."""
+        self.project_root = _resolve_path(project_root)
+        self.ignored_paths = tuple(
+            _resolve_path(path) for path in (ignored_paths or (self.project_root / "firecracker",))
+        )
+        self.project_watch_roots = build_project_watch_roots(self.project_root)
+        super().__init__()
+
+    def file_filter(self, change: Change, filename: str) -> bool:
+        """Drop file events from ignored paths such as the firecracker tree.
+
+        Returns:
+            True when the file event should still be watched.
+        """
+        resolved_path = _resolve_path(Path(filename))
+        if any(_is_relative_to(resolved_path, ignored_path) for ignored_path in self.ignored_paths):
+            return False
+        return super().file_filter(change, filename)
+
+    def watched_roots(self, watched_files: Iterable[Path]) -> frozenset[Path]:
+        """Replace repo-root watches with top-level child directories.
+
+        Returns:
+            Watch roots with the project root expanded into child directories.
+        """
+        roots = {_resolve_path(root) for root in super().watched_roots(watched_files)}
+        filtered_roots = {
+            root
+            for root in roots
+            if not any(_is_relative_to(root, ignored_path) for ignored_path in self.ignored_paths)
+        }
+        if self.project_root in filtered_roots:
+            filtered_roots.remove(self.project_root)
+            filtered_roots.update(self.project_watch_roots)
+        return frozenset(filtered_roots)
+
+
+def install_watchfiles_reloader_patch(*, project_root: Path) -> None:
+    """Install project-specific watchfiles reloader for dev and test runtimes."""
+    resolved_project_root = _resolve_path(project_root)
+
+    class ProjectWatchfilesReloader(TussilagoWatchfilesReloader):
+        def __init__(self) -> None:
+            super().__init__(project_root=resolved_project_root)
+
+    def replaced_get_reloader() -> autoreload.BaseReloader:
+        return ProjectWatchfilesReloader()
+
+    autoreload.get_reloader = replaced_get_reloader