django 在 docker 中连接数据库时出错

我在drf上做了一个小api，但是启动的时候出现错误

FROM ubuntu:22.04

ENV PYTHONUNBUFFERED=1
ENV PYTHONDONTWRITEBYTECODE=1
ARG DEBIAN_FRONTEND=noninteractive
ENV PATH=$PATH:/usr/bin/python3.11

# Установка зависимостей
RUN apt-get update && apt-get install -y --no-install-recommends \
    python3.11 \
    python3-pip \
    postgresql \
    postgresql-contrib \
     && \
    apt-get clean && rm -rf /var/lib/apt/lists/*

# Обновление pip
RUN pip install --upgrade pip --no-cache-dir

# Установка зависимостей для проекта
COPY requirements.txt /app/requirements.txt
WORKDIR /app
RUN pip install -r requirements.txt --no-cache-dir

# Копирование проекта
COPY . /app/

# Установка прав доступа
RUN chmod -R 755 /app/

# Очистка
RUN rm -rf /var/lib/apt/lists/*

docker-撰写：

version: '3.8'

volumes:
  pgdata:
  static:
  media:

services:

  django:
    build:
      context: .
    ports:
      - '8000:8000'
    container_name: django
    env_file:
      - docker/env/.env.dev
    volumes:
      - ./:/app
      - static:/app/static
      - media:/app/media
    depends_on:
      - postgres
      - redis
    command: sh -c "python3 manage.py collectstatic --no-input &&
                    python3 manage.py makemigrations &&
                    python3 manage.py migrate &&
                    python3 manage.py runserver 0.0.0.0:8000"

  nginx:
    container_name: nginx
    working_dir: /app
    image: nginx:stable-alpine
    restart: always
    ports:
      - "80:80"
    volumes:
      - static:/app/static
      - media:/app/media
      - ./docker/nginx/dev/:/etc/nginx/conf.d:ro
    links:
      - django
    depends_on:
      - django

  postgres:
    image: postgres:alpine
    container_name: postgres
    restart: always
    env_file:
      - docker/env/.env.dev
    volumes:
      - pgdata:/var/lib/postgresql/data/
    environment:
      POSTGRES_PASSWORD: example
  redis:
    image: redis:alpine
    container_name: redis
    env_file:
      - docker/env/.env.dev
    expose:
      - 6379
    volumes:
      - ./docker/redis/data:/data
   

我做错了什么？错误：

django    | connection to server at "localhost" (127.0.0.1), port 5432 failed: Connection refused
django    |     Is the server running on that host and accepting TCP/IP connections?

设置.py：

DATABASES = {
    'default': {
        'ENGINE': getenv("DB_ENGINE"),
        'NAME': getenv("DB_NAME"),
        'USER': getenv("DB_USER"),
        'PASSWORD': getenv("DB_PASSWORD"),
        'HOST': getenv("DB_HOST"),
        'PORT': getenv("DB_PORT"),
    }
}

.env:

DB_ENGINE=django.db.backends.postgresql
DB_NAME=remnovo
DB_USER=postgres
DB_PASSWORD=qwerty
DB_HOST=localhost
DB_PORT=5432