US01-02: Establish Application and Database Foundation (#47)

photo_pipeline/__init__.py

@@ -0,0 +1,9 @@
+"""Photo pipeline application package.
+
+Target architecture for the integrated photo-library pipeline (see
+INTEGRATED_PIPELINE_CONCEPT.md). US01-02 establishes the foundation: typed
+configuration, database engine/session lifecycle, versioned migrations, the
+FastAPI application factory, structured logging, and readiness.
+"""
+
+__version__ = "0.1.0"

photo_pipeline/__main__.py

@@ -0,0 +1,35 @@
+"""Application management CLI: ``python -m photo_pipeline {serve,migrate}``."""
+
+from __future__ import annotations
+
+import argparse
+from typing import Sequence
+
+from photo_pipeline.config import Config
+from photo_pipeline.db import run_migrations
+
+
+def main(argv: Sequence[str] | None = None) -> int:
+    parser = argparse.ArgumentParser(prog="photo_pipeline")
+    commands = parser.add_subparsers(dest="command", required=True)
+    commands.add_parser("serve", help="Run the API server")
+    commands.add_parser("migrate", help="Upgrade the database to the latest revision")
+    args = parser.parse_args(argv)
+
+    config = Config.from_env()
+    config.database_path.parent.mkdir(parents=True, exist_ok=True)
+
+    if args.command == "migrate":
+        run_migrations(config.database_url)
+        return 0
+
+    import uvicorn
+
+    from photo_pipeline.api.app import create_app
+
+    uvicorn.run(create_app(config), host=config.host, port=config.port)
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())

photo_pipeline/api/app.py

@@ -0,0 +1,41 @@
+"""FastAPI application factory and lifecycle.
+
+Startup runs migrations and opens the database engine; shutdown disposes it so no
+connection or engine resource leaks. The engine, session factory, and config live
+on ``app.state`` for dependencies to use. The app binds to 127.0.0.1 by default
+and exposes the versioned ``/api/v1`` surface; US01-02 ships only health.
+"""
+
+from __future__ import annotations
+
+from contextlib import asynccontextmanager
+
+from fastapi import FastAPI
+
+from photo_pipeline.api.routes import health
+from photo_pipeline.config import Config
+from photo_pipeline.db import create_db_engine, create_session_factory, run_migrations
+from photo_pipeline.logging import configure_logging
+
+
+def create_app(config: Config | None = None) -> FastAPI:
+    config = config or Config.from_env()
+    configure_logging(config.log_level, config.log_format)
+
+    @asynccontextmanager
+    async def lifespan(app: FastAPI):
+        config.database_path.parent.mkdir(parents=True, exist_ok=True)
+        run_migrations(config.database_url)
+        engine = create_db_engine(config.database_url)
+        app.state.config = config
+        app.state.engine = engine
+        app.state.session_factory = create_session_factory(engine)
+        try:
+            yield
+        finally:
+            engine.dispose()
+            app.state.engine = None
+
+    app = FastAPI(title="Photo Pipeline", version="0.1.0", lifespan=lifespan)
+    app.include_router(health.router, prefix="/api/v1")
+    return app

photo_pipeline/api/routes/health.py

@@ -0,0 +1,45 @@
+"""Liveness and readiness endpoints.
+
+``/health/live`` answers whether the process is up. ``/health/ready`` answers
+whether it can serve: the database is reachable and configured correctly (WAL,
+foreign keys). Tests and any future orchestration wait on readiness rather than a
+sleep. Readiness returns 503 until the checks pass.
+"""
+
+from __future__ import annotations
+
+from fastapi import APIRouter, Request, Response
+from sqlalchemy import text
+
+router = APIRouter(tags=["health"])
+
+
+@router.get("/health/live")
+def live() -> dict:
+    return {"status": "alive"}
+
+
+@router.get("/health/ready")
+def ready(request: Request, response: Response) -> dict:
+    checks: dict[str, object] = {}
+    ok = True
+    engine = getattr(request.app.state, "engine", None)
+    if engine is None:
+        ok = False
+        checks["database"] = "unavailable"
+    else:
+        try:
+            with engine.connect() as conn:
+                conn.execute(text("SELECT 1"))
+                journal_mode = conn.execute(text("PRAGMA journal_mode")).scalar()
+                foreign_keys = conn.execute(text("PRAGMA foreign_keys")).scalar()
+            checks["database"] = "ok"
+            checks["journal_mode"] = journal_mode
+            checks["foreign_keys"] = int(foreign_keys)
+            if str(journal_mode).lower() != "wal" or int(foreign_keys) != 1:
+                ok = False
+        except Exception:
+            ok = False
+            checks["database"] = "error"
+    response.status_code = 200 if ok else 503
+    return {"status": "ready" if ok else "not_ready", "checks": checks}

photo_pipeline/config.py

@@ -0,0 +1,52 @@
+"""Typed application configuration.
+
+Values come from ``PHOTO_PIPELINE_*`` environment variables. Secrets use
+``SecretStr`` so they are masked in logs, reprs, and model dumps, and are never
+returned by the API. Only ``.get_secret_value()`` exposes them, and only where a
+real external call needs them.
+
+pydantic-settings would do this too, but a prefix-scan over the declared fields
+is a few lines and one fewer dependency.
+"""
+
+from __future__ import annotations
+
+import os
+from pathlib import Path
+from typing import Mapping
+
+from pydantic import BaseModel, ConfigDict, SecretStr
+
+ENV_PREFIX = "PHOTO_PIPELINE_"
+
+
+class Config(BaseModel):
+    model_config = ConfigDict(frozen=True)
+
+    data_dir: Path = Path("data")
+    db_path: Path | None = None  # defaults to data_dir/photo_pipeline.db
+    host: str = "127.0.0.1"
+    port: int = 8000
+    log_level: str = "INFO"
+    log_format: str = "json"  # "json" or "text"
+
+    vision_api_key: SecretStr | None = None
+    immich_api_key: SecretStr | None = None
+
+    @property
+    def database_path(self) -> Path:
+        return self.db_path or (self.data_dir / "photo_pipeline.db")
+
+    @property
+    def database_url(self) -> str:
+        return f"sqlite:///{self.database_path}"
+
+    @classmethod
+    def from_env(cls, environ: Mapping[str, str] | None = None) -> "Config":
+        env = os.environ if environ is None else environ
+        data = {
+            name: env[ENV_PREFIX + name.upper()]
+            for name in cls.model_fields
+            if env.get(ENV_PREFIX + name.upper())
+        }
+        return cls(**data)

photo_pipeline/db.py

@@ -0,0 +1,52 @@
+"""Database engine, sessions, and migration entry point.
+
+SQLite is opened in WAL mode with foreign keys enforced on every connection
+(foreign keys and busy_timeout are per-connection; WAL is persistent but cheap to
+re-assert). Migrations run through Alembic so the same versioned schema is used at
+startup and in tests. Repository and service code depends only on ``Base`` and the
+session factory, never on SQLite specifics, so PostgreSQL stays a future option.
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from sqlalchemy import Engine, create_engine, event
+from sqlalchemy.orm import DeclarativeBase, sessionmaker
+
+_REPO_ROOT = Path(__file__).resolve().parent.parent
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+def create_db_engine(url: str, *, echo: bool = False) -> Engine:
+    connect_args = {"check_same_thread": False} if url.startswith("sqlite") else {}
+    engine = create_engine(url, echo=echo, future=True, connect_args=connect_args)
+    if url.startswith("sqlite"):
+        event.listen(engine, "connect", _apply_sqlite_pragmas)
+    return engine
+
+
+def _apply_sqlite_pragmas(dbapi_connection, _connection_record) -> None:
+    cursor = dbapi_connection.cursor()
+    cursor.execute("PRAGMA journal_mode=WAL")
+    cursor.execute("PRAGMA foreign_keys=ON")
+    cursor.execute("PRAGMA busy_timeout=5000")
+    cursor.close()
+
+
+def create_session_factory(engine: Engine) -> sessionmaker:
+    return sessionmaker(bind=engine, expire_on_commit=False, future=True)
+
+
+def run_migrations(url: str) -> None:
+    """Upgrade the database at ``url`` to the latest revision."""
+    from alembic import command
+    from alembic.config import Config as AlembicConfig
+
+    cfg = AlembicConfig(str(_REPO_ROOT / "alembic.ini"))
+    cfg.set_main_option("script_location", str(_REPO_ROOT / "migrations"))
+    cfg.set_main_option("sqlalchemy.url", url)
+    command.upgrade(cfg, "head")

photo_pipeline/logging.py

@@ -0,0 +1,44 @@
+"""Structured logging.
+
+JSON lines carrying ``job_id``, ``asset_id``, and ``operation_id`` when present,
+so later stages can correlate work across the API, worker, and jobs. Secrets are
+never passed to the logger; ``SecretStr`` masks them even if one slips through.
+"""
+
+from __future__ import annotations
+
+import json
+import logging
+import sys
+from datetime import datetime, timezone
+
+CONTEXT_FIELDS = ("job_id", "asset_id", "operation_id")
+
+
+class JsonFormatter(logging.Formatter):
+    def format(self, record: logging.LogRecord) -> str:
+        payload = {
+            "ts": datetime.fromtimestamp(record.created, timezone.utc).isoformat(),
+            "level": record.levelname,
+            "logger": record.name,
+            "message": record.getMessage(),
+        }
+        for field in CONTEXT_FIELDS:
+            value = getattr(record, field, None)
+            if value is not None:
+                payload[field] = value
+        if record.exc_info:
+            payload["exc"] = self.formatException(record.exc_info)
+        return json.dumps(payload, default=str)
+
+
+def configure_logging(level: str = "INFO", fmt: str = "json") -> None:
+    handler = logging.StreamHandler(sys.stderr)
+    if fmt == "json":
+        handler.setFormatter(JsonFormatter())
+    else:
+        handler.setFormatter(logging.Formatter("%(asctime)s %(levelname)s %(name)s %(message)s"))
+    root = logging.getLogger()
+    root.handlers.clear()
+    root.addHandler(handler)
+    root.setLevel(level.upper())

photo_pipeline/models/__init__.py

@@ -0,0 +1,9 @@
+"""SQLAlchemy persistence models.
+
+Importing this package registers every model on ``Base.metadata``, which the
+Alembic environment relies on.
+"""
+
+from photo_pipeline.models.assets import Asset, AssetPath
+
+__all__ = ["Asset", "AssetPath"]

photo_pipeline/models/assets.py

@@ -0,0 +1,59 @@
+"""Stable asset identity and path history.
+
+A file path is mutable metadata, never identity: ``assets.id`` is a generated
+UUID that never changes across moves, renames, or archival. ``asset_paths``
+records every path an asset has occupied. ``state_version`` supports optimistic
+concurrency; ``created_at``/``updated_at`` are the audit timestamps.
+
+Later-stage columns (canonical link, safety score, archive location) are added by
+the migrations of the stories that own them, not speculatively here.
+"""
+
+from __future__ import annotations
+
+from datetime import datetime
+
+from sqlalchemy import DateTime, ForeignKey, Integer, String, func
+from sqlalchemy.orm import Mapped, mapped_column
+
+from photo_pipeline.db import Base
+
+
+class Asset(Base):
+    __tablename__ = "assets"
+
+    id: Mapped[str] = mapped_column(String, primary_key=True)
+    original_path: Mapped[str] = mapped_column(String, nullable=False)
+    current_path: Mapped[str | None] = mapped_column(String, unique=True)
+
+    current_sha256: Mapped[str | None] = mapped_column(String)
+    pixel_sha256: Mapped[str | None] = mapped_column(String)
+    phash: Mapped[str | None] = mapped_column(String)
+    hash_version: Mapped[int] = mapped_column(Integer, nullable=False, default=1)
+    byte_size: Mapped[int | None] = mapped_column(Integer)
+
+    discovered_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
+    missing_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
+    availability_state: Mapped[str] = mapped_column(String, nullable=False, default="active")
+
+    state_version: Mapped[int] = mapped_column(Integer, nullable=False, default=1)
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now()
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now(), onupdate=func.now()
+    )
+
+
+class AssetPath(Base):
+    __tablename__ = "asset_paths"
+
+    asset_id: Mapped[str] = mapped_column(
+        ForeignKey("assets.id"), primary_key=True
+    )
+    path: Mapped[str] = mapped_column(String, primary_key=True)
+    valid_from: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), primary_key=True
+    )
+    valid_until: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
+    reason: Mapped[str | None] = mapped_column(String)