Fix worker race condition - single uvicorn worker + tolerate duplicates

backend/Dockerfile

@@ -11,5 +11,6 @@ RUN pip install --no-cache-dir -r requirements.txt
 
 COPY . .
 
-# Tables are created at runtime by SQLAlchemy in app/main.py lifespan
-CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000", "--workers", "4"]
+# Single worker avoids race condition during DB initialization.
+# For a personal app this is fine; async handles concurrent requests well.
+CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]

backend/app/main.py

@@ -10,21 +10,27 @@ from app.api import auth, activities, routes, health, records, upload
 
 
 async def init_db():
-    """Create tables then seed admin, with retries for slow DB startup."""
-    for attempt in range(10):
+    """Create tables then seed admin, with retries for slow DB startup.
+
+    Multiple uvicorn workers may race here on first start. We tolerate
+    duplicate table errors since they just mean another worker got there first.
+    """
+    for attempt in range(15):
         try:
-            # Step 1: create all tables (separate connection so it commits cleanly)
             async with engine.begin() as conn:
                 await conn.run_sync(Base.metadata.create_all)
             break
         except Exception as e:
-            if attempt == 9:
+            msg = str(e).lower()
+            if "already exists" in msg or "duplicate" in msg or "pg_type_typname" in msg:
+                print("Tables already created by another worker - skipping")
+                break
+            if attempt == 14:
                 raise
-            print(f"DB not ready yet (attempt {attempt + 1}/10): {e}")
-            await asyncio.sleep(3)
+            print(f"DB not ready yet (attempt {attempt + 1}/15): {e}")
+            await asyncio.sleep(2)
 
-    # Step 2: try to enable TimescaleDB hypertable (separate connection,
-    # failure here is non-fatal - falls back to plain Postgres)
+    # Try TimescaleDB hypertable (non-fatal)
     try:
         async with engine.begin() as conn:
             await conn.execute(text(
@@ -34,24 +40,35 @@ async def init_db():
     except Exception as e:
         print(f"TimescaleDB hypertable skipped: {e}")
 
-    # Step 3: seed admin user
+    # Seed admin user (only if password is configured)
+    if not settings.admin_password:
+        print("ADMIN_PASSWORD not set - skipping admin user seed")
+        return
+
     from sqlalchemy import select
     from app.models.user import User
     from app.core.security import hash_password
 
-    async with AsyncSessionLocal() as db:
-        result = await db.execute(
-            select(User).where(User.username == settings.admin_username)
-        )
-        if not result.scalar_one_or_none():
-            admin = User(
-                username=settings.admin_username,
-                hashed_password=hash_password(settings.admin_password),
-                is_admin=True,
+    try:
+        async with AsyncSessionLocal() as db:
+            result = await db.execute(
+                select(User).where(User.username == settings.admin_username)
             )
-            db.add(admin)
-            await db.commit()
-            print(f"Admin user '{settings.admin_username}' created")
+            if not result.scalar_one_or_none():
+                admin = User(
+                    username=settings.admin_username,
+                    hashed_password=hash_password(settings.admin_password),
+                    is_admin=True,
+                )
+                db.add(admin)
+                await db.commit()
+                print(f"Admin user '{settings.admin_username}' created")
+    except Exception as e:
+        msg = str(e).lower()
+        if "duplicate" in msg or "unique" in msg:
+            print("Admin user already exists - skipping seed")
+        else:
+            raise
 
 
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