allow optionally dependency installation

defaults/main.yml

@@ -1,5 +1,11 @@
 ---
 dockerengine_package: docker
+# The role requires epel repository and pip to work
+# You can use dockerengine_dependencies to install these dependencys
+# dockerengine_dependencies:
+#   - epel-release
+#   - python2-pip
+dockerengine_dependencies: []
 dockerengine_docker_group_enabled: False
 
 dockerengine_secure_registries: []

molecule/ec2-centos-7/playbook.yml

@@ -1,6 +1,10 @@
 ---
 - name: Converge
   hosts: all
+  vars:
+    dockerengine_dependencies:
+      - epel-release
+      - python2-pip
 
   roles:
     - role: xoxys.docker-engine

tasks/install.yml

@@ -5,6 +5,12 @@
         name: "{{ dockerengine_package }}"
         state: installed
 
+    - name: Install dependencies
+      package:
+        name: "{{ item }}"
+        state: installed
+      loop: "{{ dockerengine_dependencies }}"
+
     - name: Install python dependencies
       pip:
         name: