anchor.diff:  only required so that the `etcdctl` command is available to issue operations in
   later steps.
   
  +[[downgrade-docker]]
  +== Downgrading Docker
  +
  +{product-title} 3.2 requires Docker 1.9.1 and also supports Docker 1.10.3,
  +however {product-title} 3.1 requires Docker 1.8.2.
  +
  +Downgrade to Docker 1.8.2 on each host using the following steps:
  +
  +. Remove all local containers and images on the host. Any pods backed by a
  +replication controller will be recreated.
  ++
  +[WARNING]
  +====
  +The following commands are destructive and should be used with caution.
  +====
  ++
  +Delete all containers:
  ++
  +----
  +# docker rm $(docker ps -a -q)
  +----
  ++
  +Delete all images:
  ++
  +----
  +# docker rmi $(docker images -q)
  +----
  +
  +. Use `yum swap` (instead of `yum downgrade`) to install Docker 1.8.2:
  ++
  +----
  +# yum swap docker-* docker-*1.8.2
  +# sed -i 's/--storage-opt dm.use_deferred_deletion=true//' /etc/sysconfig/docker-storage
  +# systemctl restart docker
  +----
  +
  +. You should now have Docker 1.8.2 installed and running on the host. Verify with
  +the following:
  ++
  +----
  +# docker version
  +Client:
  + Version:      1.8.2-el7
  + API version:  1.20
  + Package Version: docker-1.8.2-10.el7.x86_64
  +[...]
  +
  +# systemctl status docker
  +● docker.service - Docker Application Container Engine
  +   Loaded: loaded (/usr/lib/systemd/system/docker.service; enabled; vendor preset: disabled)
  +   Active: active (running) since Mon 2016-06-27 15:44:20 EDT; 33min ago
  +[...]
  +----
  +
   [[downgrade-reinstalling-rpms]]
   == Reinstalling RPMs
   
  -Disable the OpenShift Enteprise 3.1 repositories, and re-enable the 3.0
  +Disable the {product-title} 3.2 repositories, and re-enable the 3.1
   repositories:
   
   ====
   ----
   # subscription-manager repos \
  -    --disable=rhel-7-server-ose-3.1-rpms \
  -    --enable=rhel-7-server-ose-3.0-rpms
  +    --disable=rhel-7-server-ose-3.2-rpms \
  +    --enable=rhel-7-server-ose-3.1-rpms
   ----
   ====
   
  
positive.code: ----
  # ETCD_DIR=/var/lib/etcd/
  # mv $ETCD_DIR /var/lib/etcd.orig
  # cp -Rp /var/lib/openshift/etcd-backup-<timestamp>/ $ETCD_DIR
  # chcon -R --reference /var/lib/etcd.orig/ $ETCD_DIR
  # chown -R etcd:etcd $ETCD_DIR
  ----
  
negative.code: 
  ====
  ----
  /etc/sysconfig/atomic-openshift-master
  /etc/etcd/etcd.conf <1>
  ----
  <1> Only required if using external etcd.
  