sqlalchemy не может соедениться с базой данных postgresql

Делаю сборку fastapi-postgresql и у меня возникла проблема, sqlalchemy не может подключиться к бд postgresql.

Вот лог ошибки:

web_1  |        Is the server running on that host and accepting TCP/IP connections?
web_1  | connection to server at "localhost" (::1), port 5432 failed: Cannot assign requested address
web_1  |        Is the server running on that host and accepting TCP/IP connections?
web_1  | 
web_1  | (Background on this error at: https://sqlalche.me/e/14/e3q8)

Вот docker-compose.yml:

version: '3.9'

services:
  web:
    build: .
    command: uvicorn app.main:app --host localhost --port 8000
    volumes:
      - .:/usr/src/db_ok
    ports:
      - 8000:8000
    depends_on:
      - db

  db:
    image: postgres
    volumes:
      - postgres_data:/var/lib/postgresql/data/
    environment:
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=postgres
      - POSTGRES_DB=db_ok
    ports: 
      - 5432:5432

volumes:
  postgres_data:

Dockerfile:

FROM python:3.10
WORKDIR /app
COPY ./app ./app
COPY req.txt req.txt
RUN pip3 install -r req.txt

Подключение к бд через sqlalchemy:

DATABASE_URL = 'postgresql://postgres:postgres@localhost:5432/db_ok'


engine = create_engine(DATABASE_URL)
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)