ansible does not play roles and tasks I'm learning ansible and I'm having a problem, when I run my playbook, it only runs the gather_fact task and does not play my roles.  On the other hand when I run just a module with the ansible command -m or playing the playbook locally, there my roles are played. Do you have an idea ? I posted the question on the google group, but for the moment no answers. thank you in advance
If instead of using the command line:
ansible-playbook -u root --private -key ~ / .ssh / id_rsa centos7.yml -i xxx.xxx.xxx.xxx,  

I use: 

ansible-playbook -u root centos7.yml -i xxx.xxx.xxx.xxx, 

It works.