Ansible include roles that have been defined in hostvars

Question

I am trying to do the following:

1. define appropriate host roles in hostvars
2. create a role to call ONLY the roles that relate to specific host and have been defined in a variable in hostvars

Is there a way to do this?

eg:

host_vars/hostname_one/mail.yml

roles_to_install:
  - role_one
  - role_two
  - ...

run_all_roles.yml

---
- hosts: '{{ TARGET }}'

  become: yes
  ... 
  roles:
    - { role: "roles_to_install"}

Obviously this does not work.

Is there a way to make ansible-playbook -i <hosts_file> run_all_roles.yml -e "TARGET=hostname_one" to run?

Answer 1

As I commented the solution was easier than expected:

--- 
- hosts: '{{ TARGET }}' 
  become: yes 

  vars_files: 
  - ./vars/main.yml 

  roles: 
    - { role: "roleA", when: "'roleA' in roles_to_install" } 
    - { role: "roleB", when: "'roleB' in roles_to_install" } 
    ... 

Assuming that a correct roles_to_install var is defined inside host_vars/$fqdn/main.yml like so:

---
roles_to_install:
  - roleA
  - roleB
  - ...

Thank you for you assistance guys