报错截图如下：

我的docker-compose.yml文件如下：

version: "3"

services:
  voting-app:
    build: ./voting-app/.
    volumes:
     - ./voting-app:/app
    ports:
      - "5000:80"
    links:
      - redis
    networks:
      - front-tier
      - back-tier

  result-app:
    build: ./result-app/.
    volumes:
      - ./result-app:/app
    ports:
      - "5001:80"
    links:
      - db
    networks:
      - front-tier
      - back-tier

  worker:
    build: ./worker
    links:
      - db
      - redis
    networks:
      - back-tier

  redis:
    image: redis
    ports: ["6379"]
    networks:
      - back-tier

  db:
    image: postgres:9.4
    volumes:
      - "db-data:/var/lib/postgresql/data"
    networks:
      - back-tier

volumes:
  db-data:

networks:
  front-tier:
  back-tier:

环境是vmware funsion搭建的centos7虚拟机，之前的demo项目都能跑成功。老师这是什么问题导致的build失败？