fix the duplicate entry of rabbitmq_refresh

playbooks/roles/launch_ec2/tasks/main.yml

@@ -56,6 +56,7 @@
     instance_tags: "{{ instance_tags }}"
     volumes:
       - device_name: /dev/sda1
+        volume_type: gp2
         volume_size: "{{ root_ebs_size }}"
         delete_on_termination: true
     zone: "{{ zone }}"