Roles en Ansible

Los roles de Ansible nos permitirán reutilizar partes de código entre playbooks simplemente incluyendo el role pertinente, de este modo cuando necesitemos realizar algún cambio en el role solo tendremos que tocar un único fichero.

En este ejemplo tendremos un playbook base que incluirá tres roles, uno de configuración de screen, otro de instalación de utilidades básicas en Gentoo y otro de utilidades básicas en Ubuntu.

Creamos la estructura de directorios necesaria:

mkdir -p roles/configureScreen/files
mkdir -p roles/configureScreen/tasks
mkdir -p roles/installUtilitiesGentoo/tasks
mkdir -p roles/installUtilitiesUbuntu/tasks

Creamos los ficheros necesarios:

vi roles/configureScreen/files/.screenrc

caption always "%{= kw}%-w%{= gW}%n %t%{-}%+w %-= - %Y-%m-%d %C:%s"

vi roles/configureScreen/tasks/main.yml

- name: Copy .screenrc file
  copy:
    src: "{{ role_path }}/files/.screenrc"
    dest: /root/.screenrc
    owner: root
    group: root
    mode: '0644'

vi roles/installUtilitiesGentoo/tasks/main.yml

- name: Install basic utilities Gentoo
  portage:
    package: "{{item}}"
    state: present
  with_items:
  - sys-fs/ncdu
  - sys-process/htop
  - net-analyzer/tcpdump
  - net-analyzer/ngrep
  - app-misc/screen

vi roles/installUtilitiesUbuntu/tasks/main.yml

- name: Install basic utilities Ubuntu
  apt:
    name: ['ncdu', 'htop', 'tcpdump', 'ngrep', 'screen', 'strace', 'net-tools', 'python-apt']
    update_cache: yes

La estructura gráficamente quedaría así:

roles/
├── configureScreen
│   ├── files
│   └── tasks
│       └── main.yml
├── installUtilitiesGentoo
│   └── tasks
│       └── main.yml
└── installUtilitiesUbuntu
    └── tasks
       └── main.yml

Finalmente escribimos el playbook que hará uso de los roles:

vi base.yml

- hosts: all
  gather_facts: yes
  tasks:
    - name: groupByOS
      group_by: key=os_{{ ansible_distribution }}
    
- hosts: os_Gentoo
  roles:
    - installUtilitiesGentoo
    - configureScreen

- hosts: os_Ubuntu
  roles:
    - installUtilitiesUbuntu
    - configureScreen

Ejecutamos el playbook:

ansible-playbook base.yml

PLAY [all] ********************************************************************************************************************************************************************************************************************************************************************************************************************

TASK [Gathering Facts] ********************************************************************************************************************************************************************************************************************************************************************************************************
ok: [kr0mtest2]
ok: [kr0mtest3]
ok: [test00]
ok: [kr0mtest4]
ok: [kr0mtest]

TASK [group_by] ***************************************************************************************************************************************************************************************************************************************************************************************************************
ok: [kr0mtest]
ok: [kr0mtest2]
ok: [kr0mtest3]
ok: [kr0mtest4]
ok: [test00]

PLAY [os_Gentoo] **************************************************************************************************************************************************************************************************************************************************************************************************************

TASK [Gathering Facts] ********************************************************************************************************************************************************************************************************************************************************************************************************
ok: [kr0mtest2]
ok: [kr0mtest3]
ok: [kr0mtest4]
ok: [kr0mtest]

TASK [installUtilitiesGentoo : Install basic utilities Gentoo] ****************************************************************************************************************************************************************************************************************************************************************
ok: [kr0mtest3] => (item=sys-fs/ncdu)
ok: [kr0mtest4] => (item=sys-fs/ncdu)
ok: [kr0mtest2] => (item=sys-fs/ncdu)
ok: [kr0mtest] => (item=sys-fs/ncdu)
ok: [kr0mtest3] => (item=sys-process/htop)
ok: [kr0mtest4] => (item=sys-process/htop)
ok: [kr0mtest2] => (item=sys-process/htop)
ok: [kr0mtest] => (item=sys-process/htop)
ok: [kr0mtest3] => (item=net-analyzer/tcpdump)
ok: [kr0mtest4] => (item=net-analyzer/tcpdump)
ok: [kr0mtest2] => (item=net-analyzer/tcpdump)
ok: [kr0mtest] => (item=net-analyzer/tcpdump)
ok: [kr0mtest3] => (item=net-analyzer/ngrep)
ok: [kr0mtest4] => (item=net-analyzer/ngrep)
ok: [kr0mtest2] => (item=net-analyzer/ngrep)
ok: [kr0mtest] => (item=net-analyzer/ngrep)
ok: [kr0mtest3] => (item=app-misc/screen)
ok: [kr0mtest4] => (item=app-misc/screen)
ok: [kr0mtest2] => (item=app-misc/screen)
ok: [kr0mtest] => (item=app-misc/screen)

TASK [configureScreen : Copy .screenrc file] **********************************************************************************************************************************************************************************************************************************************************************************
ok: [kr0mtest3]
ok: [kr0mtest2]
ok: [kr0mtest4]
ok: [kr0mtest]

PLAY [os_Ubuntu] **************************************************************************************************************************************************************************************************************************************************************************************************************

TASK [Gathering Facts] ********************************************************************************************************************************************************************************************************************************************************************************************************
ok: [test00]

TASK [installUtilitiesUbuntu : Install basic utilities Ubuntu] ****************************************************************************************************************************************************************************************************************************************************************
 [WARNING]: Could not find aptitude. Using apt-get instead

changed: [test00]

TASK [configureScreen : Copy .screenrc file] **********************************************************************************************************************************************************************************************************************************************************************************
changed: [test00]

PLAY RECAP ********************************************************************************************************************************************************************************************************************************************************************************************************************
kr0mtest                   : ok=5    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   
kr0mtest2                  : ok=5    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   
kr0mtest3                  : ok=5    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   
kr0mtest4                  : ok=5    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   
test00                     : ok=5    changed=2    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0