anchor.diff:  
   These instructions are stored in a file called a Dockerfile. Docker reads this Dockerfile when you request a build of an image, executes the instructions, and returns a final image.
   
  -**How does a container work?**
  +**How does a Container work?**
   
   A container consists of an operating system, user-added files, and meta-data. As we've seen, each container is built from an image. That image tells Docker what the container holds, what process to run when the container is launched, and a variety of other configuration data. The Docker image is read-only. When Docker runs a container from an image, it adds a read-write layer on top of the image (using a union file system as we saw earlier) in which your application can then run.
   
  -### Docker Machine
  +## Docker Machine
   
   Machine makes it really easy to create Docker hosts on your computer, on cloud providers and inside your own data center. It creates servers, installs Docker on them, then configures the Docker client to talk to them.
   
  
positive.code: docker images
  ----
  
  At first, this list ist empty. Now, let's get a plain `jboss/wildfly` image from your instructor's registry:
  
  [source, text]
  ----
  docker pull <INSTRUCTOR_IP>:5000/wildfly
  ----
  
  Typically, you'll 
  
  You can see, that Docker is downloading the immage with it's different layers.
  In a traditional Linux boot, the kernel first mounts the root File System as read-only, checks its integrity, and then switches the whole rootfs volume to read-write mode.
  When Docker mounts the rootfs, it starts read-only, as in a traditional Linux boot, but then, instead of changing the file system to read-write mode, it takes advantage of a union mount to add a read-write file system over the read-only file system. In fact there may be multiple read-only file systems stacked on top of each other. We think of each one of these file systems as a layer.
  At first, the top read-write layer has nothing in it, but any time a process creates a file, this happens in the top layer. And if something needs to update an existing file in a lower layer, then the file gets copied to the upper layer and changes go into the copy. The version of the file on the lower layer cannot be seen by the applications anymore, but it is there, unchanged.
  We call the union of the read-write layer and all the read-only layers a union file system.
  
  .Docker Layers
  image::images/plain-wildfly0.png[]
  
negative.code: ----
  docker run --name db -d -p 5432:5432 -e POSTGRES_USER=ticketmonster -e POSTGRES_PASSWORD=ticketmonster-docker <INSTRUCTOR_IP>:5000/postgres
  ----
  
  This command starts a container named "db" from the image in your instructor's registry "<INSTRUCTOR_IP>:5000/postgres". As this will not be present locally, it needs to be downloaded first. But you'll have a very quick connection to the instructor registry and this shouldn't take long.
  The two "-e" options define environment variables which are read by the db at startup and allow us to access the database with this user and password.
  Finally, the "-d" option tells docker to start a demon process. Which means, that the console window, you're running this command in, will be available again after it is issued. If you skip this parameter, the console will be directly showing the output from the process.
  