Docker部署Django+PostgreSQL时角色django2存在性矛盾问题

问题现象 #

执行docker-compose up --build时触发数据库连接错误：

django.db.utils.OperationalError: FATAL: role "django2" does not exist

但手动执行CREATE ROLE django2;命令时，又返回角色已存在的提示：

ERROR:  role "django2" already exists

相关配置 #

settings.py 数据库配置 #

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': 'zane_db',
        'USER': 'django2',
        'PASSWORD': 'django2',
        'HOST': 'db',
        'PORT': 5432
    }
}

docker-compose.yml 配置 #

version: '3.8'

services:
  web:
    tty: true
    build: .
    command: python3 /docekr/manage.py runserver 0.0.0.0:8000
    volumes:
      - .:/docekr
    ports:
      - 8000:8000
    depends_on:
      - db
  db:
    image: postgres:11
    volumes:
      - postgres_data:/var/lib/postgresql/data/
    environment:
      - "POSTGRES_HOST_AUTH_METHOD=trust"

volumes:
  postgres_data:

Dockerfile 配置 #

FROM python:3.9

ENV PYTHONUBBUFFERED 1
ENV PYTHONDONTWRITEBYTECODE 1

WORKDIR /zane

COPY Pipfile Pipfile.lock /zane/
RUN pip3 install pipenv && pipenv install --system

COPY . /zane/

注册视图代码（供参考） #

letters = ["A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"]
numbers = ["1", "2", "3", "4", "5", "6", "7", "8", "9",]
characters = letters + numbers
length = 5
token = "".join(random.sample(characters, length))

def signup(request):
    if request.method == "POST":
        context = {'has_error': False, 'data': request.POST}
        global password
        global password2
        global email
        global username
        email = request.POST.get('email')
        username = request.POST.get('username')
        password = request.POST.get('password')
        password2 = request.POST.get('password2')

        body = render_to_string('authentication/email/email_body.html', {
            'username': username,
            'token': token,
        })
        send_mail(
            "Email Confirmation",
            body,
            'tadejtilinger@gmail.com',
            [email]
        )
        return redirect('email-confirmation')
    return render(request, 'authentication/signup.html')


def email_confirmation(request):

    if request.method == "POST":
        context = {'has_error': False, 'data': request.POST}

        code = request.POST.get('code')
        
        if code == token:
            if len(password) < 8:
                ############custom message
                context['has_error'] = True

            if password != password2:
                ############custom message
                context['has_error'] = True

            if not validate_email(email):
                ############custom message
                context['has_error'] = True

            if not username:
                ############custom message
                context['has_error'] = True

            if models.CustomUser.objects.filter(username=username).exists():
                ############custom message
                context['has_error'] = True

                return render(request, 'authentication/signup.html', context, status=409)

            if models.CustomUser.objects.filter(email=email).exists():
                ############custom message
                context['has_error'] = True

                return render(request, 'authentication/signup.html', context, status=409)

            if context['has_error']:
                return render(request, 'authentication/signup.html', context)

            user = models.CustomUser.objects.create_user(username=username, email=email)
            user.set_password(password)
            user.save()

            user = authenticate(request, username=username, password=password)
            login(request)

    return render(request, 'authentication/email/email_confirmation.html')

解决步骤 #

1. 清除PostgreSQL持久化数据卷 #

本地数据卷可能残留了不一致的角色状态，先彻底删除关联卷：

docker-compose down -v

2. 配置PostgreSQL自动初始化环境变量 #

PostgreSQL官方镜像支持通过环境变量自动创建用户、数据库，修改docker-compose.yml的db服务配置：

db:
  image: postgres:11
  volumes:
    - postgres_data:/var/lib/postgresql/data/
  environment:
    - POSTGRES_USER=django2
    - POSTGRES_PASSWORD=django2
    - POSTGRES_DB=zane_db

容器启动时会自动创建匹配settings.py的用户和数据库，无需手动执行SQL。

3. 修正web服务路径拼写错误 #

Dockerfile中WORKDIR为/zane，但docker-compose.yml中路径拼写错误，统一修改为：

web:
  tty: true
  build: .
  command: python3 /zane/manage.py runserver 0.0.0.0:8000
  volumes:
    - .:/zane
  ports:
    - 8000:8000
  depends_on:
    - db

4. 重新构建启动服务 #

执行命令重新部署：

docker-compose up --build

额外提示：优化视图全局变量问题 #

注册视图中使用的global password、global email等全局变量，在多用户并发场景下会导致数据混乱。建议改用session存储临时数据，或创建EmailVerification模型存储验证记录（包含用户名、邮箱、token、过期时间等字段）。

内容的提问来源于stack exchange，提问作者P Studio