Ansible: Loop over the items of a host list and execute role

Question

I have an application composed of micro modules distributed on multiple hosts.

inventory:

[moduleA_hostgroup]
host1
host2
[moduleB_hostgroup]
host2
host3
[moduleC_hostgroup]
host1
host4

Each module has specific location and configuration files. I'd like to fetch the config for all installed modules

vars:
modules:
  moduleA:
    path: "/opt/moduleA"
    files_to_fetch: ['*.conf']
  moduleB:
    path: "/etc/moduleB"
    files_to_fetch: ['*.json','*.properties']
  moduleC:
    path: "/etc/moduleC"
    files_to_fetch: ['*.conf','*.json']

I can retrieve those files for the modules by running a role:

- hosts: moduleA_hostgroup
  pre_tasks:
    - name: pre_tasks
      set_fact:
        path: "{{ modules.moduleA.path }}"
        pattern: "{{ modules.moduleA.files_tofetch }}'
  roles:
  - ../roles/fetch_module_config

- hosts: moduleB_hostgroup
  pre_tasks:
    - name: pre_tasks
      set_fact:
        path: "{{ modules.moduleB.path }}"
        pattern: "{{ modules.moduleB.files_tofetch }}'
  roles:
  - ../roles/fetch_module_config


etc..

Issue is, I'll have to run the roles as many times as there are modules Is there an elegant way to loop through the module list and run the role on the module hostgroup only?

Answer 1

include_role should do the trick.

---
- hosts: hosts
  vars:
    modules:
      moduleA:
        path: "/opt/moduleA"
        files_to_fetch: ['*.conf']
      moduleB:
        path: "/etc/moduleB"
        files_to_fetch: ['*.json','*.properties']
      moduleC:
        path: "/etc/moduleC"
        files_to_fetch: ['*.conf','*.json']
  tasks:
    - name: Collecting Data
      include_role:
        name: fetch_module_config
      vars:
        path: "{{ item.value.path }}"
        pattern: "{{ item.value.files_to_fetch }}"
      loop: "{{ modules | dict2items }}"
      when: item.key in group_names

But that is rather clunky. IMO a role is not right for such a task, you should consider converting it into a task and then use include_task instead.