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

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}