FastAPI skeleton: health, OpenAPI, core wiring (task 042dfc5c)

FastAPI skeleton: health, OpenAPI, core wiring (task 042dfc5c)

api/__init__.py

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+"""NestQuest API service.
+
+A standalone FastAPI deployable that owns the NestQuest database and
+exposes it over HTTP to the Home Assistant integration (panel plane) and
+the admin PWA (admin plane).  See Feature 16 (task cd03735b) in the
+project tracker for the full contract.
+
+This package imports the NestQuest domain ``core`` WITHOUT executing
+``custom_components/nestquest/__init__.py`` — that parent package's
+``__init__.py`` imports ``homeassistant``, which is absent from the
+API's runtime.  The coupling is encapsulated in
+:mod:`api.nestquest_core`, which loads ``core`` by file location with
+:mod:`importlib.util` and registers it under the distinct top-level name
+``nestquest_core`` (no ``sys.path`` mutation, no generic top-level
+names published).  It is a TRANSITIONAL coupling that Feature 18 will
+revisit: once the integration becomes a thin API client and ``core``
+moves out of the integration bundle, this helper goes away.
+"""
+from __future__ import annotations

api/app.py

@@ -0,0 +1,99 @@
+"""The NestQuest FastAPI application.
+
+This module builds the ASGI app for the NestQuest API service (Feature
+16).  The skeleton here wires the bundled ``core`` (Feature 15) and
+exposes the two endpoints every later task depends on:
+
+- ``GET /health`` — returns ``200`` with a JSON status body once the
+  app has imported core, opened the database, and applied migrations;
+  a cheap ``SELECT 1`` confirms the connection is live without leaking
+  the filesystem path on an unauthenticated route.
+- ``GET /docs`` — FastAPI's auto-served OpenAPI document (Swagger UI);
+  ``/openapi.json`` is the raw schema.  No extra wiring is needed;
+  FastAPI serves both by default.
+
+The database is opened and migrated in a FastAPI lifespan context so a
+startup failure (e.g. an unwritable path) surfaces as a startup error
+rather than the first request.  The connection is closed on shutdown.
+
+This module exports ONLY the :func:`create_app` factory — there is no
+module-level app instance, because building one at import time would
+read ``NESTQUEST_DB_PATH`` at import (and fail-fast on a missing value)
+before any worker is ready to report it.  Serve with::
+
+    uvicorn --factory api.app:create_app
+
+so the factory runs on each worker startup and reads the environment
+then.
+"""
+from __future__ import annotations
+
+from contextlib import asynccontextmanager
+from collections.abc import AsyncIterator
+
+from fastapi import FastAPI
+
+from api.config import ApiConfig
+from api.database import DatabaseState, make_database
+
+
+def _build_lifespan(db_path: str):
+    """Return a lifespan that opens+migrates then closes one database.
+
+    Captured as a closure so the app factory can hand the configured
+    path in without threading it through FastAPI's lifespan signature.
+    """
+
+    @asynccontextmanager
+    async def lifespan(app: FastAPI) -> AsyncIterator[None]:
+        state = make_database(db_path)
+        app.state.db = state
+        try:
+            await state.open_and_migrate()
+            yield
+        finally:
+            await state.close()
+
+    return lifespan
+
+
+def create_app(config: ApiConfig | None = None) -> FastAPI:
+    """Build the NestQuest API FastAPI app.
+
+    ``config`` defaults to one built from the process environment, so
+    ``uvicorn --factory api.app:create_app`` picks up
+    ``NESTQUEST_DB_PATH`` (and fails fast on startup if it is missing).
+    Tests pass an explicit config so each test gets a hermetic temp
+    SQLite file.
+    """
+    cfg = config if config is not None else ApiConfig.from_env()
+
+    app = FastAPI(
+        title="NestQuest API",
+        description=(
+            "Standalone HTTP service that owns the NestQuest database and "
+            "exposes it to the Home Assistant integration (panel plane) and "
+            "the admin PWA (admin plane)."
+        ),
+        version="0.1.0",
+        lifespan=_build_lifespan(cfg.db_path),
+    )
+
+    @app.get("/health", summary="Service health")
+    async def health() -> dict[str, str]:
+        """Return service health.
+
+        Returns ``200`` with ``{"status": "ok"}`` once the lifespan has
+        opened and migrated the database.  A cheap ``SELECT 1`` against
+        the live connection confirms the database is reachable WITHOUT
+        leaking the filesystem path on an unauthenticated route; if the
+        connection is dead the query raises and the probe fails.
+        """
+        state: DatabaseState = app.state.db
+        await state.database.fetch_one("SELECT 1")
+        return {"status": "ok"}
+
+    return app
+
+
+__all__ = ["create_app"]

api/config.py

@@ -0,0 +1,68 @@
+"""Configuration for the NestQuest API service.
+
+The API reads its single configuration knob — the SQLite database path —
+from the ``NESTQUEST_DB_PATH`` environment variable.  Unlike a dev
+convenience default, a missing or empty value is a configuration ERROR,
+not a silent fallback to a predictable world-writable temp path: the API
+owns the database (it is the writer of record per Feature 16's
+contract), and silently dropping data into ``$TMPDIR/nestquest.db``
+would lose it at reboot.  ``ApiConfig.from_env`` therefore RAISES when
+the variable is unset or empty.  This mirrors the integration's
+"explicit settings object" discipline (Feature 15's
+``core.settings``): the API never reads HA config; callers pass the
+resolved path into the database wiring.
+
+Serving: the app is built with the factory ``api.app:create_app`` — run
+it with ``uvicorn --factory api.app:create_app`` so the factory reads
+the environment on each worker startup rather than at import time.
+"""
+from __future__ import annotations
+
+import os
+from dataclasses import dataclass
+
+#: Environment variable holding the SQLite file path.  The API opens
+#: this file on startup (creating it if absent) and applies migrations.
+#: REQUIRED — unset or empty raises :class:`ConfigError` from
+#: :meth:`ApiConfig.from_env`.
+DB_PATH_ENV = "NESTQUEST_DB_PATH"
+
+
+class ConfigError(RuntimeError):
+    """Raised when required API configuration is missing or invalid."""
+
+
+@dataclass(frozen=True)
+class ApiConfig:
+    """Resolved API configuration.
+
+    Currently a single field — the SQLite path — but kept as a dataclass
+    so later tasks (auth, SSE, settings persistence) can extend it
+    without touching the call sites that read ``db_path``.
+    """
+
+    db_path: str
+
+    @classmethod
+    def from_env(cls, env: dict[str, str] | None = None) -> "ApiConfig":
+        """Build configuration from the process environment.
+
+        ``env`` defaults to ``os.environ``; tests pass an explicit dict
+        so they are hermetic (no monkeypatch of the global environ).
+
+        Raises :class:`ConfigError` when ``NESTQUEST_DB_PATH`` is unset
+        or empty/whitespace-only — there is no silent default, because a
+        default in the temp directory would silently lose data at reboot.
+        """
+        source = env if env is not None else os.environ
+        raw = source.get(DB_PATH_ENV, "").strip()
+        if not raw:
+            raise ConfigError(
+                f"{DB_PATH_ENV} must be set to a writable SQLite file path "
+                f"(it is unset or empty — the API will not fall back to a "
+                f"temp directory and silently lose data)"
+            )
+        return cls(db_path=raw)
+
+
+__all__ = ["ApiConfig", "ConfigError", "DB_PATH_ENV"]

api/database.py

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+"""Database wiring for the NestQuest API service.
+
+The API owns the database (it is the writer of record per Feature 16's
+contract).  This module owns one application-lifetime
+:class:`core.db.NestQuestDatabase`: it opens the SQLite file at the
+configured path on startup, applies migrations (creating the schema on
+a fresh file), and closes the connection on shutdown.
+
+The executor callable passed into ``NestQuestDatabase`` mirrors the
+contract of ``hass.async_add_executor_job``: schedule a synchronous
+callable on a worker and await its result.  HA's own version lives on
+the event loop; the API is not HA, so it uses
+:func:`asyncio.to_thread` for the same effect — sqlite3 calls run on a
+worker thread and only plain data returns to the event loop.
+"""
+from __future__ import annotations
+
+import asyncio
+import logging
+from typing import Any
+
+from api.nestquest_core import core_db, core_migrations
+
+LOGGER = logging.getLogger(__name__)
+
+#: The async SQLite wrapper.  Re-exported so route handlers and later
+#: tasks reach it through the API package, not the bundled core.
+NestQuestDatabase = core_db.NestQuestDatabase
+
+#: The migration runner.  Re-exported for the same reason.
+apply_migrations = core_migrations.apply_migrations
+
+
+async def _executor(fn: Any, *args: Any, **kwargs: Any) -> Any:
+    """Run a synchronous callable on a worker thread and await its result.
+
+    Mirrors the contract of ``hass.async_add_executor_job`` so the
+    bundled ``NestQuestDatabase`` (written against that contract) works
+    unchanged in the API process: sqlite3 calls never block the event
+    loop, and only plain Python data (row tuples,
+    :class:`core.db.ExecutionResult`) crosses back.
+    """
+    return await asyncio.to_thread(fn, *args, **kwargs)
+
+
+class DatabaseState:
+    """Holds the live database wrapper and its resolved path.
+
+    A small container so the lifespan and the route handlers share one
+    authoritative reference; FastAPI's lifespan stores one of these on
+    ``app.state.db`` and the health route reads it back.
+    """
+
+    __slots__ = ("database", "db_path")
+
+    def __init__(self, database: NestQuestDatabase, db_path: str) -> None:
+        self.database = database
+        self.db_path = db_path
+
+    async def open_and_migrate(self) -> None:
+        """Open the connection and apply migrations to the latest version."""
+        LOGGER.info("Opening NestQuest database at %s", self.db_path)
+        await self.database.open(self.db_path)
+        version = await apply_migrations(self.database)
+        LOGGER.info("NestQuest schema at version %d", version)
+
+    async def close(self) -> None:
+        """Close the connection; safe to call even if open failed."""
+        await self.database.close()
+
+
+def make_database(db_path: str) -> DatabaseState:
+    """Construct a :class:`DatabaseState` for the given path (not yet open)."""
+    return DatabaseState(NestQuestDatabase(_executor), db_path)
+
+
+__all__ = [
+    "DatabaseState",
+    "NestQuestDatabase",
+    "apply_migrations",
+    "make_database",
+]

api/nestquest_core.py

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+"""Transitional coupling: import ``core`` without importing Home Assistant.
+
+The NestQuest domain ``core`` package (Feature 15) is bundled INSIDE the
+Home Assistant integration at ``custom_components/nestquest/core/``.
+Importing it the obvious way — ``import custom_components.nestquest.core``
+— would execute ``custom_components/nestquest/__init__.py``, which
+imports ``homeassistant``.  Home Assistant is NOT installed in the API
+service's runtime, so that import raises ``ModuleNotFoundError`` and the
+API cannot start.
+
+``core`` itself is a clean, Home-Assistant-free package: its
+``__init__.py`` is a bare docstring and every internal import is
+relative (``from .db import ...``).  It can therefore be imported by
+file location as a standalone package.
+
+This module loads ``core`` with :func:`importlib.util.spec_from_file_location`
+— registering it under the distinct top-level name ``nestquest_core``
+with ``submodule_search_locations`` set to the bundled ``core``
+directory — so its relative imports resolve against that directory
+without touching ``sys.path``.  No generic top-level name (``db``,
+``const``, ``schema``, ...) is published, so nothing here can silently
+shadow a future dependency, and the integration's HA-coupled
+``__init__.py`` is never executed: ``custom_components.nestquest`` is
+never imported.
+
+Usage::
+
+    from api.nestquest_core import core_db, core_migrations
+    # core_db.NestQuestDatabase, core_migrations.apply_migrations, ...
+
+This is a TRANSITIONAL coupling.  Feature 18 (task 430f7f98) converts
+the integration into a thin API client and moves ``core`` out of the
+integration bundle; once that lands, this bootstrap helper goes away and
+the API imports ``core`` as an ordinary installed dependency.
+
+NOTE on the pytest process: the suite's ``conftest.py`` stubs the
+parent integration package and imports ``custom_components.nestquest.core.*``
+BEFORE any API test runs, so two copies of the core package coexist in
+the pytest process — the one registered here as ``nestquest_core.*``
+(loaded by file location) and the conftest-stubbed
+``custom_components.nestquest.core.*``.  Later tasks must NOT compare
+class or exception identity across these two copies: a
+``nestquest_core.db.NestQuestDatabase`` is a DIFFERENT class object from
+``custom_components.nestquest.core.db.NestQuestDatabase`` even though
+they share source.  Operate on a single copy within any one code path.
+"""
+from __future__ import annotations
+
+import importlib
+import importlib.util
+import sys
+from pathlib import Path
+from types import ModuleType
+
+#: The repository root (this file is ``<root>/api/nestquest_core.py``).
+_REPO_ROOT: Path = Path(__file__).resolve().parent.parent
+
+#: The bundled ``core`` package directory, inside the HA integration.
+_CORE_DIR: Path = _REPO_ROOT / "custom_components" / "nestquest" / "core"
+
+#: The ``core`` package's ``__init__.py`` — a bare docstring, so loading
+#: it by file location executes no imports of its own.
+_CORE_INIT: Path = _CORE_DIR / "__init__.py"
+
+#: The distinct top-level name under which the bundled ``core`` package
+#: is registered in ``sys.modules``.  A distinctive name (rather than the
+#: generic ``core``) avoids publishing shadow-able top-level names and
+#: keeps the bundled copy separate from the conftest-stubbed
+#: ``custom_components.nestquest.core`` present in the pytest process.
+_CORE_MODULE_NAME = "nestquest_core"
+
+
+def _load_core() -> ModuleType:
+    """Load the bundled ``core`` package by file location and return it.
+
+    Registers the package under :data:`_CORE_MODULE_NAME` in
+    ``sys.modules`` with ``submodule_search_locations`` pointing at the
+    bundled directory, so its relative imports (``from .db import ...``)
+    resolve to ``nestquest_core.<submodule>`` against that directory
+    without mutating ``sys.path``.  Idempotent: a second call returns
+    the already-registered module.
+    """
+    existing = sys.modules.get(_CORE_MODULE_NAME)
+    if existing is not None:
+        return existing
+    spec = importlib.util.spec_from_file_location(
+        _CORE_MODULE_NAME,
+        _CORE_INIT,
+        submodule_search_locations=[str(_CORE_DIR)],
+    )
+    if spec is None or spec.loader is None:
+        raise ImportError(f"could not load core from {_CORE_INIT}")
+    module = importlib.util.module_from_spec(spec)
+    sys.modules[_CORE_MODULE_NAME] = module
+    spec.loader.exec_module(module)
+    return module
+
+
+#: The bundled core package, loaded by file location and registered as
+#: ``nestquest_core`` in ``sys.modules``.  Held here so callers import the
+#: submodules through it (``nestquest_core.db``, ``nestquest_core.migrations``)
+#: the same relative way the integration does.
+core: ModuleType = _load_core()
+
+#: Re-exported for convenience; route handlers import these names from
+#: here rather than reaching into the core package directly.
+core_db = importlib.import_module(f"{_CORE_MODULE_NAME}.db")
+core_migrations = importlib.import_module(f"{_CORE_MODULE_NAME}.migrations")
+
+__all__ = ["core", "core_db", "core_migrations"]