title: ERROR: In file './docker-compose.yml', service 'build' must be a mapping not a string
body: <p>I am working on a php docker application.Am facing an error while trying 
  docker-compose up command. Trying to connect a php application to mysql.</p>
  
  <p>My docker compose file :-</p>
  
  <pre><code> version: '2'
   services:
   web:
   container_name: modeloPHP5.4-Apache
   build: .
   ports:
   — 8889:80
  
   volumes:
   — ./www:/var/www/html
  
   links:
   — db
  
   db:
   container_name: modeloMySQL
   build:
   context: ./
   dockerfile: DockerfileDB
   volumes:
   — /var/lib/mysql
  
   ports:
   — 3307:3306
  
   environment:
  
   MYSQL_ROOT_PASSWORD: password
   MYSQL_USER: user
   MYSQL_PASSWORD: password
   MYSQL_DATABASE: db_test
  </code></pre>