Add new deps, writen a db engine, docker-compose and .env-example

backend/app/db_engine.py

@@ -0,0 +1,42 @@
+from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine, async_sessionmaker
+from sqlalchemy.orm import DeclarativeBase
+import dotenv
+import os
+
+dotenv.load_dotenv()
+
+PG_USER = dotenv.get_key(".env", "PG_USER")
+PG_PASSWORD = dotenv.get_key(".env", "PG_PASSWORD")
+PG_HOST = dotenv.get_key(".env", "PG_HOST")
+PG_PORT = dotenv.get_key(".env", "PG_PORT")
+PG_DB = dotenv.get_key(".env", "PG_DB")
+
+DATABASE_URL = (
+    f"postgresql+asyncpg://{PG_USER}:{PG_PASSWORD}@{PG_HOST}:{PG_PORT}/{PG_DB}"
+)
+
+engine = create_async_engine(
+    DATABASE_URL,
+    echo=False,     
+    future=True,
+)
+
+async_session_maker = async_sessionmaker(
+    engine,
+    class_=AsyncSession,
+    expire_on_commit=False,
+)
+
+
+class Base(DeclarativeBase):
+    pass
+
+async def get_async_session():
+    async with async_session_maker() as session:
+        yield session
+
+
+async def init_db():
+    async with engine.begin() as conn:
+        await conn.run_sync(Base.metadata.create_all)
+