anchor.diff:  *** external_addr (bridged network)
   ** Other discovery mechanisms
   *** Route 53
  -*** Elstic IP addresses
  +*** Elastic IP addresses
   *** GossipRouter
   *** Block of addresses in VPC
   ** IAM security roles (S3 access)
  
positive.code: Which type of network is used is defined by the `--network` option, e.g. `--network=host`.
  
  Network `none` has no communication to the outside world and is used purely for Docker containers running on the same
  box.
  
  Network `bridge` is the default and can be used for containers to talk to each other. This is done via a `bridge0` or
  `docker0` virtual network interface installed by Docker on the host.
  
  
  ** Local
  
negative.code: The advantage of running Docker images in the cloud, rather than cloud-specific images is that the Docker
  images are the same across different clouds, whereas cloud images are always specific to a given cloud.
  
  The predefined docker image we'll use is https://hub.docker.com/r/belaban/jgroups. It contains a number
  of interactive <<demos>>, ie. demos which require a TTY.
  
  The difference between running locally, or running in a cloud lies in the JGroups configuration and the Docker
  