feat: create backend skeleton

backend/src/dependencies/__init__.py

@@ -0,0 +1,3 @@
+from .integrations.asyncio import FromDishka, Scope, inject
+
+__all__ = ["FromDishka", "Scope", "inject"]

backend/src/dependencies/container.py

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+from dishka import make_async_container
+
+from dependencies.providers.postgres import DbProvider
+
+container = make_async_container(DbProvider())

backend/src/dependencies/integrations/__init__.py

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+from . import asyncio
+
+__all__ = ["asyncio"]

backend/src/dependencies/integrations/asyncio.py

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+from collections.abc import Callable
+
+from dishka import FromDishka, Scope
+from dishka.integrations.base import wrap_injection
+
+from dependencies.container import container
+
+
+def inject[**P, T](
+    _func: Callable[P, T] | None = None, *, scope: Scope | None = None
+) -> Callable[P, T] | Callable[[Callable[P, T]], Callable[P, T]]:
+    def decorator(func: Callable[P, T]) -> Callable[P, T]:
+        return wrap_injection(
+            func=func,
+            is_async=True,
+            container_getter=lambda _args, _kwargs: container,
+            scope=scope,
+        )
+
+    if _func is None:
+        return decorator
+    return decorator(_func)
+
+
+__all__ = ["FromDishka", "Scope", "container", "inject"]

backend/src/dependencies/providers/postgres.py

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+from collections.abc import AsyncGenerator
+
+import asyncpg
+from dishka import Provider, Scope, provide
+
+from utils.env import env
+
+
+async def _init_connection(conn: asyncpg.Connection) -> None:
+    await conn.execute("SET timezone TO 'UTC'")
+
+
+class DbProvider(Provider):
+    @provide(scope=Scope.APP)
+    async def get_pool(self) -> AsyncGenerator[asyncpg.Pool]:
+        # noinspection PyUnresolvedReferences
+        pool = await asyncpg.create_pool(
+            dsn=env.db.connection_url,
+            min_size=env.db.min_pool_size,
+            max_size=env.db.max_pool_size,
+            command_timeout=60,
+            init=_init_connection,
+        )
+        try:
+            yield pool
+        finally:
+            await pool.close()