use APIRouter instead of another FastAPI

api/kiwi_vpn_api/main.py

@@ -15,13 +15,12 @@ from fastapi import FastAPI
 from .config import Config, Settings
 from .db import Connection
 from .db.schemas import User
-from .routers import admin, dn, user
+from .routers import main_router
 
 settings = Settings.get()
 
-app = FastAPI()
 
-api = FastAPI(
+app = FastAPI(
     title="kiwi-vpn API",
     description="This API enables the `kiwi-vpn` service.",
     contact={
@@ -37,11 +36,7 @@ api = FastAPI(
     redoc_url=settings.redoc_url if not settings.production_mode else None,
 )
 
-api.include_router(admin.router)
-api.include_router(user.router)
-api.include_router(dn.router)
-
-app.mount("/api", api)
+app.include_router(main_router)
 
 
 @app.on_event("startup")

api/kiwi_vpn_api/routers/__init__.py

@@ -0,0 +1,10 @@
+from fastapi import APIRouter
+
+from . import admin, user
+
+main_router = APIRouter(prefix="/api/v1")
+
+main_router.include_router(admin.router)
+main_router.include_router(user.router)
+
+__all__ = ["main_router"]