anchor.diff:  
   === Create your first Docker image
   
  -_Hello World_ Dockerfile is shown:
  +Create a new text file _Dockerfile_ in an empty directory and use the following contents:
   
   .Hello World Dockerfile
   [source, text]
  
positive.code: busybox             latest              3d5bcd78e074        4 days ago          1.113 MB
  ----
  
  ==== Run WildFly
  
  Create a new text file _Dockerfile_ in an empty directory:
  
  [source, text]
  ----
  
negative.code: . Allows tar file auto-extraction in the image, for example, `ADD app.tar.gz /opt/var/myapp`.
  . Allows files to be downloaded from a remote URL. However, the downloaded files will become part of the image. This causes the image size to bloat. So its recommended to use `curl` or `wget` to download the archive explicitly, extract, and remove the archive.
  
  ==== Import and export images
  
  Docker images can be saved using `save` command to a .tar file:
  
  