roles/docker: Install and set up Docker daemon

The *docker* role configures the Docker daemon on the managed machine.

roles/docker/templates/docker-latest.sysconfig.j2

@@ -0,0 +1,34 @@
+# /etc/sysconfig/docker-latest
+
+# Modify these options if you want to change the way the docker daemon runs
+OPTIONS='{% if docker_allow_unprivileged|bool %}-G docker {% endif %}--selinux-enabled'
+DOCKER_CERT_PATH=/etc/docker
+
+# If you want to add your own registry to be used for docker search and docker
+# pull use the #ADD_REGISTRY option to list a set of registries, each prepended
+# with --add-registry flag. The first registry added will be the first registry
+# searched.
+#ADD_REGISTRY='--add-registry registry.access.redhat.com'
+
+# If you want to block registries from being used, uncomment the BLOCK_REGISTRY
+# option and give it a set of registries, each prepended with --block-registry
+# flag. For example adding docker.io will stop users from downloading images
+# from docker.io
+# BLOCK_REGISTRY='--block-registry'
+
+# Enable insecure registry communication by appending the registry URL
+# to the INSECURE_REGISTRY variable below and uncommenting it
+# INSECURE_REGISTRY='--insecure-registry '
+
+# On SELinux System, if you remove the --selinux-enabled option, you
+# also need to turn on the docker_transition_unconfined boolean.
+# setsebool -P docker_transition_unconfined
+
+# Location used for temporary files, such as those created by
+# docker load and build operations. Default is /var/lib/docker/tmp
+# Can be overriden by setting the following environment variable.
+# DOCKER_TMPDIR=/var/tmp
+
+# Controls the /etc/cron.daily/docker-logrotate cron job status.
+# To disable, uncomment the line below.
+# LOGROTATE=false