我想用marathon部署一个docker容器，如果docker镜像没有授权，镜像可以正常拉取，但是当我尝试从需要授权的存储库中拉取镜像时，任务部署失败，响应为

Failed to launch container: Failed to run 'docker -H unix:///var/run/docker.sock pull example.com/web:laest': exited with status 1; stderr='Error response from daemon: repository example.com/web not found: does not exist or no pull access '

我在node和master上将/var/run/docker.sock文件的权限改为777，但问题仍然出现，似乎权限不是问题的根本原因；我尝试在节点上运行“docker login”，手动拉取图片，然后马拉松任务正确运行，我的马拉松json如下：

{
  "id": "/web",
  "cmd": "docker login --username='sam' --passwoer='123456' example.com/web:latest",
  "cpus": 0.3,
  "mem": 32,
  "disk": 0,
  "instances": 1,
  "env": {
     "EMAIL_USE_TLS": "False",
     "DATABASE_URI": "mysql://user:123456@RDS:3306/test"
   },
  "container": {
     "type": "DOCKER",
     "volumes": [
      {
       "containerPath": "/data/supervisor/",
       "hostPath": "/data/workspace/logs/supervisor/",
       "mode": "RW"
      }
   ],
  "docker": {
    "image": "daocloud.io/gizwits2015/gwaccounts:1.6.0",
    "network": "BRIDGE",
    "portMappings": [
      {
        "containerPort": 0,
        "hostPort": 0,
        "servicePort": 10000,
        "protocol": "tcp",
        "labels": {}
      }
    ],
    "privileged": false,
    "parameters": [
      {
        "key": "add-host",
        "value": "RDS:10.66.125.161"
      }
    ],
    "forcePullImage": false
  }
},
"portDefinitions": [
  {
    "port": 10000,
    "protocol": "tcp",
    "name": "default",
    "labels": {}
  }
 ]
}

我怎样才能拉马拉松授权的形象？