Ansible: How installing a group of packages?

Installing a set of packages with Ansible

The context

I need to install a group of packages on multiple Linux servers. Ansible is the right tool for that.

The host file: hosts

[test_machines]
   test1.my_domain.com
   test2.my_domain.com
[dev]
   dev1.my_domain.com
   dev2.my_domain.com
[uat]
   uat1.my_domain.com
   uat2.my_domain.com
[prod]
   prd1.my_domain.com
   prd2.my_domain.com

The playbook : add_packages.yml

- hosts: all
  vars_files:
    - data/all_my_packages.yml
  tasks:
  - name: Ensure a set of packages is installed.
    yum:
      name={{ item.name }}
      state={{ item.state }}
    with_items: '{{ packages }}'

The datafile: data/all_my_packages.yml

packages:
 - { name: 'glibc.i686', state: 'present' }
 - { name: 'glibc.x86_64', state: 'present' }
 - { name: 'glibc-common', state: 'present' }
 - { name: 'glibc-devel', state: 'present' }
 - { name: 'glibc-headers', state: 'present' }
 - { name: 'libstdc++.i686', state: 'present' }
 - { name: 'libstdc++.x86_64', state: 'present' }
 - { name: 'libstdc++-devel.x86_64', state: 'present' }
 - { name: 'compat-libstdc++-33.i686', state: 'present' }
 - { name: 'compat-libstdc++-33.x86_64', state: 'present' }
 - { name: 'compat-libstdc++-296-2.96-144.el6.i686', state: 'present' }
 - { name: 'pam.i686', state: 'present' }
 - { name: 'pam.x86_64', state: 'present' }
 - { name: 'gtk2.i686', state: 'present' }
 - { name: 'gtk2.x86_64', state: 'present' }
 - { name: 'xorg-x11-xauth.x86_64', state: 'present' }
 - { name: 'dos2unix', state: 'present' }

The command

Checking on subset of servers:
# ansible-playbook add_packages.yml --check -i hosts --limit test_machines


Running:
# ansible-playbook add_packages.yml -i hosts