Ansible - Roles

Roles allow the grouping of related tasks, files, vars, templates, etc. for easy reuse.

Roles expect specific dir names. This is what the directory structure of a project would normally look like:

site.yml
webservers.yml
fooservers.yml
roles/
    common/
        tasks/          # main list of tasks
        handlers/       # handlers
        files/          # files that can be deployed
        templates/      # templates go here
        vars/           # other vars
        defaults/       # default vars
        meta/           # meta data
    webservers/
        tasks/
        defaults/
        meta/

This file often has platform specific stuff:

tasks/main.yml


- name: added in 2.4, previously you used 'include'
  import_tasks: redhat.yml
  when: ansible_facts['os_family']|lower == 'redhat'
- import_tasks: debian.yml
  when: ansible_facts['os_family']|lower == 'debian'

Roles are searched for here:

• roles/ ( relative to play book )
• /etc/ansible/roles

Use a role like this ( classic way ):

---
- hosts: webservers
  roles:
    - common
    - webservers

If these files exist:

roles/x/tasks/main.yml	add these tasks to play
roles/x/handlers/main.yml	add these handlers to play
roles/x/vars/main.yml	add these vars to play
roles/x/defaults/main.yml	add these vars to play
roles/x/meta/main.yml	add these role dependencies to play

• “Any copy, script, template or include tasks (in the role) can reference files in roles/x/{files,templates,tasks}/ (dir depends on task) without having to path them relatively or absolutely.”
• Default role variables have the lowest priority out of all variables and are defined here: defaults/main.yml
• Roles only run once even when defined multiple times unless:
  • params are different
  • Add allow_duplicates: true to the meta/main.yml

Execution order:

• pre_tasks in the play
• any triggered handlers
• each role in roles
• tasks in play
• any triggered handlers
• post_tasks in the play
• any triggered handlers

Import role and include role ( new way ):

---
- hosts: webservers
  tasks:
    - debug:
        msg: "before we run our role"
    - import_role:
        name: example
    - include_role:
        name: example
    - debug:
        msg: "after we ran our role"

Full path for a role, just the name, or name as a param and variables included:

---
- hosts: webservers
  roles:
    - role: '/path/to/my/roles/common'
    - common
    - role: foo_app_instance
      vars:
        dir: '/opt/a'
        app_port: 5000

Using include_role with vars:

---
- hosts: webservers
  tasks:
    - include_role:
        name: foo_app_instance
      vars:
        dir: '/opt/a'
        app_port: 5000

Conditionally import a role:

---
- hosts: webservers
  tasks:
    - include_role:
        name: some_role
      when: "ansible_facts['os_family'] == 'RedHat'"

Using tags with roles:

---
- hosts: webservers
  roles:
    - role: foo
      tags:
        - bar
        - baz
    # using YAML shorthand, this is equivalent to the above:
    - { role: foo, tags: ["bar", "baz"] }

Same, newer syntax:

---
- hosts: webservers
  tasks:
    - import_role:
        name: foo
      tags:
        - bar
        - baz

• Tags in an include_role task are applied to that task but not the role.

Role Dependencies

roles/x/meta/main.yml

---
dependencies:
  - role: common
    vars:
      some_parameter: 3
  - role: apache
    vars:
      apache_port: 80
  - role: postgres
    vars:
      dbname: blarg
      other_parameter: 12

Modules can be included in a role. The structure looks like this:

roles/
    my_custom_modules/
        library/
            module1
            module2