title: Docker volume must be a mapping, not a string
body: <p>I have the following file at <code>./wordpress/docker-compose.yaml</code>:</p>
  
  <pre><code>version: '3.3'
  
  serivces:
    db:
      image: mysql:5.7
      volumes:
        - db_data:/var/lib/mysql
      restart: always
      evironment:
        MYSQL_ROOT_PASSWORD: password
        MYSQL_DATABASE: wordpress
        MYSQL_USER: wordpress
        MYSQL_PASSWORD: wordpress
  
    wordpress:
      depends_on:
        - db
      image: wordpress:latest
      ports:
        - "8000:80"
      volumes:
        - ./:/var/www/html
      restart: always
      environment:
        WORDPRESS_DB_HOST: db:3306
        WORDPRESS_DB_USER: wordpress
        WORDPRESS_DB_PASSWORD: wordpress
  
  volumes:
    db_data
  </code></pre>
  
  <p>When I run <code>cd ./wordpress &amp;&amp; docker-compose up -d</code> I get the following error:</p>
  
  <pre><code>ERROR: In file './docker-compose.yaml', volume must be a mapping, not a string.
  </code></pre>
  
  <p>Can anyone tell me what I'm doing wrong?</p>