feat: connect FastAPI to Neon PostgreSQL

app.py

@@ -1,8 +1,13 @@
-from fastapi import FastAPI
+from fastapi import FastAPI, HTTPException, status
+
+from database import check_database_connection
 
 app = FastAPI(
     title="Anderson — Semantic Retrieval for RAG",
-    description="Démonstration de recherche sémantique destinée à alimenter un système RAG.",
+    description=(
+        "Démonstration de recherche sémantique destinée "
+        "à alimenter un système RAG."
+    ),
     version="0.1.0",
 )
 
@@ -17,4 +22,21 @@ def root():
 
 @app.get("/health")
 def health():
-    return {"status": "ok"}
+    return {"status": "ok"}
+
+
+@app.get("/health/database")
+def database_health():
+    try:
+        connected = check_database_connection()
+    except Exception:
+        raise HTTPException(
+            status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
+            detail="Database unavailable",
+        )
+
+    return {
+        "status": "ok",
+        "database": "connected",
+        "connection_test": connected,
+    }

database.py

@@ -0,0 +1,31 @@
+import os
+
+from dotenv import load_dotenv
+from sqlalchemy import create_engine, text
+
+load_dotenv()
+
+database_url = os.getenv("DATABASE_URL")
+
+if not database_url:
+    raise RuntimeError("La variable DATABASE_URL est absente.")
+
+# SQLAlchemy doit utiliser explicitement le pilote psycopg.
+sqlalchemy_database_url = database_url.replace(
+    "postgresql://",
+    "postgresql+psycopg://",
+    1,
+)
+
+engine = create_engine(
+    sqlalchemy_database_url,
+    pool_pre_ping=True,
+    pool_size=5,
+    max_overflow=5,
+)
+
+
+def check_database_connection() -> bool:
+    with engine.connect() as connection:
+        result = connection.execute(text("SELECT 1"))
+        return result.scalar_one() == 1

requirements.txt

@@ -7,6 +7,7 @@ colorama==0.4.6
 fastapi==0.141.1
 filelock==3.32.3
 fsspec==2026.7.0
+greenlet==3.5.5
 h11==0.16.0
 hf-xet==1.6.0
 httpcore==1.0.9
@@ -15,14 +16,18 @@ httpx==0.28.1
 huggingface_hub==1.28.0
 idna==3.19
 packaging==26.3
+psycopg==3.3.4
+psycopg-binary==3.3.4
 pydantic==2.13.4
 pydantic_core==2.46.4
 python-dotenv==1.2.3
 PyYAML==6.0.3
+SQLAlchemy==2.0.52
 starlette==1.6.0
 tqdm==4.70.0
 typing-inspection==0.4.4
 typing_extensions==4.16.0
+tzdata==2026.3
 uvicorn==0.52.4
 watchfiles==1.2.0
 websockets==17.0.1