added rpm caching for to docker repo (#3718)

roles/container-engine/docker/tasks/main.yml

@@ -124,7 +124,6 @@
     line: 'obsoletes=0'
   when: ansible_distribution in ["CentOS","RedHat"] and not is_atomic
 
-
 - name: ensure docker packages are installed
   action: "{{ docker_package_info.pkg_mgr }}"
   args:

roles/container-engine/docker/templates/rh_docker.repo.j2

@@ -3,6 +3,7 @@ name=Docker-CE Repository
 baseurl={{ docker_rh_repo_base_url }}
 enabled=1
 gpgcheck=1
+keepcache={{ docker_rpm_keepcache | default('1') }}
 gpgkey={{ docker_rh_repo_gpgkey }}
 {% if http_proxy is defined %}proxy={{ http_proxy }}{% endif %}
 
@@ -11,5 +12,6 @@ name=Docker-Engine Repository
 baseurl={{ dockerproject_rh_repo_base_url }}
 enabled=1
 gpgcheck=1
+keepcache={{ docker_rpm_keepcache | default('1') }}
 gpgkey={{ dockerproject_rh_repo_gpgkey }}
 {% if http_proxy is defined %}proxy={{ http_proxy }}{% endif %}