title: Cant login with docker compose to Postgres via pgadmin
body: <p>I have the following docker-compose:</p>
  
  <pre><code>version: '3.1'
  services:
    db:
      image: postgres
      restart: always
      environment:
        POSTGRES_PASSWORD: postgres
      volumes:
        - postgres:/pgdata
      ports:
          - "5432:5432"
  
    pdadmin:
      image: dpage/pgadmin4
      restart: always
      ports:
        - "8080:80"
      environment:
       PGADMIN_DEFAULT_EMAIL: example@gmail.com 
       PGADMIN_DEFAULT_PASSWORD: example
  
  volumes:
    postgres: 
  </code></pre>
  
  <p>when I try to login to postgres via pgadmin i am getting the error: <code>password authentication failed for user "postgres"</code></p>
  
  <p>I am trying with user <code>postgres</code> and password <code>postgres</code>.<br>
  I also tryied to add explisit <code>POSTGRES_USER</code> to the env with no success.  </p>
  
  <p>How can I login to my postgres database?<br>
  Thanks</p>