title: Docker - psql: django.db.utils.OperationalError: FATAL: role "admin" does not exist
body: <p>I've configured docker and postgres for my Django project. </p>
  
  <p>When I do <code>python manage.py runserver 0:8000</code>, 
  it gives me this error: <code>django.db.utils.OperationalError: FATAL:  role "admin" does not exist</code></p>
  
  <p>However, I've been used the same configs with my previous projects and everything seems fine in those.</p>
  
  <p>Here is my docker-compose.yml file</p>
  
  <pre><code>version: '3'
  
  services:
    db:
      image: postgres
      environment:
        - POSTGRES_DB=myproject
        - POSTGRES_USER=admin
        - POSTGRES_PASSWORD=admin_pass
      container_name: myproject_postgress
      volumes:
        - ./data/db:/var/lib/postgresql/data
  
   myproject:
      build: ./myproject
      container_name: myproject
      env_file:
        - .env
      command: "tail -f /dev/null"
      volumes:
        - ./myproject:/web
      ports:
        - "8000:8000"
      depends_on:
        - db
      links:
        - db:postgres
      environment:
        - DJANGO_SETTINGS_MODULE=myproject.settings.local
  </code></pre>
  
  <p>And here is my Database section in my settings file:</p>
  
  <pre><code>DATABASES = {
      'default': {
          'ENGINE': 'django.db.backends.postgresql_psycopg2',
          'NAME': 'myproject',
          'USER': 'admin',
          'PASSWORD': 'admin_pass',
          'HOST': 'postgres',
          'PORT': '',
      }
  }
  </code></pre>
  
  <p>These are the SAME with the ones in the docker-compose.yml</p>
  
  <p>When I connect my database from command line, I can see that there is user 'admin'. (locally of course)
  Without docker, it wont give any error. So what I am doing wrong with the docker?</p>
  
  <p>PS: 
  In my previous projects, I passed the env file to the docker using env_file instead of using environment section in the docker-compose.yml
  I did try that too, but its not worked. </p>
  
  <p>I am searching for a long time.
  Thanks!</p>