title: What's the container of a base docker image?
body: <p>I am learning to use docker. I know that each docker image is build on a base image which doesn't have a parent.</p>
  
  <p>Then from a base image, we can customize some stuff via containers (maybe a very short life container) to commit a new image.</p>
  
  <p>So I understand that the process is like this: base image -> container -> new image 1 -> container -> new image 2</p>
  
  <p>However, I inspect the json data of the base image. I still can see that it has a container's information:</p>
  
  <pre><code>[{
  "Architecture": "amd64",
  "Author": "",
  "Comment": "",
  "Config": {
      "AttachStderr": false,
      "AttachStdin": false,
      "AttachStdout": false,
      "Cmd": null,
      "CpuShares": 0,
      "Cpuset": "",
      "Domainname": "",
      "Entrypoint": null,
      "Env": null,
      "ExposedPorts": null,
      "Hostname": "3f37dbc61890",
      "Image": "",
      "Labels": null,
      "MacAddress": "",
      "Memory": 0,
      "MemorySwap": 0,
      "NetworkDisabled": false,
      "OnBuild": null,
      "OpenStdin": false,
      "PortSpecs": null,
      "StdinOnce": false,
      "Tty": false,
      "User": "",
      "Volumes": null,
      "WorkingDir": ""
  },
  "Container": "3f37dbc61890b0bb37cc8479db94602bcc2d6e177d76c0f3d7d53346c0dc580c",
  "ContainerConfig": {
      "AttachStderr": false,
      "AttachStdin": false,
      "AttachStdout": false,
      "Cmd": [
          "/bin/sh",
          "-c",
          "#(nop) ADD file:777fad733fc954c0c161670c48c10ea1787a6e5d544daa20e55d593279df3fa3 in /"
      ],
      "CpuShares": 0,
      "Cpuset": "",
      "Domainname": "",
      "Entrypoint": null,
      "Env": null,
      "ExposedPorts": null,
      "Hostname": "3f37dbc61890",
      "Image": "",
      "Labels": null,
      "MacAddress": "",
      "Memory": 0,
      "MemorySwap": 0,
      "NetworkDisabled": false,
      "OnBuild": null,
      "OpenStdin": false,
      "PortSpecs": null,
      "StdinOnce": false,
      "Tty": false,
      "User": "",
      "Volumes": null,
      "WorkingDir": ""
  },
  "Created": "2015-04-21T22:18:45.67739694Z",
  "DockerVersion": "1.6.0",
  "Id": "706766fe101906a1a6628173c2677173a5f8c6c469075083f3cf3a8f5e5eb367",
  "Os": "linux",
  "Parent": "",
  "Size": 188104128,
  "VirtualSize": 188104128
  }]
  </code></pre>
  
  <blockquote>
    <p>3f37dbc61890b0bb37cc8479db94602bcc2d6e177d76c0f3d7d53346c0dc580c is
    the container id of the base image.</p>
  </blockquote>
  
  <p>what is a container of a base image? I feel like it becomes the hostname. 
  What is the hostname actually?</p>