docker compose出现ERROR: Version in “./docker-compose.yml” is unsupported错误

问题

以下是我的docker-compose.yml文件

version: “2”
services:
  web:
   build: .
   environment:
    MONGO_URI="mongodb://ravimongo:27017"
   ports:
    — “3000:3000”
   links:
    — ravimongo
   depends_on:
    — ravimongo
  ravimongo:
   image: mongo:3.2.6
   ports:
     — “27017:27017”

下面是错误信息：

ERROR: Version in "./docker-compose.yml" is unsupported. You might be seeing this error because you're using the wrong Compose file version. Either specify a supported version ("2.0", "2.1", "3.0") and place your service definitions under the `services` key, or omit the `version` key and place your service definitions at the root of the file to use version 1.
For more on the Compose file format versions, see https://docs.docker.com/compose/compose-file/

docker-compose的版本信息：

docker-compose version 1.11.2, build dfed245
docker-py version: 2.1.0
CPython version: 2.7.12
OpenSSL version: OpenSSL 1.0.2j  26 Sep 2016

docker版本信息：

Client:
 Version:      17.03.1-ce
 API version:  1.27
 Go version:   go1.7.5
 Git commit:   c6d412e
 Built:        Tue Mar 28 00:40:02 2017
 OS/Arch:      darwin/amd64

Server:
 Version:      17.03.1-ce
 API version:  1.27 (minimum version 1.12)
 Go version:   go1.7.5
 Git commit:   c6d412e
 Built:        Fri Mar 24 00:00:50 2017
 OS/Arch:      linux/amd64
 Experimental: true

我使用了 http://www.yamllint.com/ 和 https://codebeautify.org/yaml-validator验证这个yaml文件，没发现有什么问题。