Role inclusion mechanics

Archives Ansible Developer
1

Hi,

I’d like to make a feature request wrt to role dependencies. Currently, role dependencies must be defined via the dependencies section in meta/main.yaml and always execute prior to the tasks in the parent role. However, we are encountering a particular issue as follows:

We have RoleA which has a dependency defined on RoleB. However, we’d like to execute a task before RoleB is executed. We do not control RoleB, and therefore, cannot modify its tasks. With the current role dependency mechanics, there doesn’t seem to be a way to execute pre_tasks before the execution of RoleB, short of creating a dummy role C which is included before RoleB.

Therefore, I was wondering whether the role inclusion mechanics could be made similar across playbooks and roles. That is, allow roles to include child roles, just as a playbook includes dependent roles, with pre_tasks and post_tasks. The advantages would be a simpler learning curve, since the mechanisms are more consistent, and also, provide more flexibility in terms of how roles can be composed, especially when dealing with third party roles.

cheers,

/Nuwan

2

Hi Nuwan,

It sounds like rather than making RoleB a dep on RoleA, you should simply include them in order, with any other pre-tasks you need to execute in another role, as follows:

roles:

  • pre_tasks_role
  • RoleB
  • RoleA

Beyond that, I would be more inclined to add pre/post task support to roles rather than modifying the inclusion mechanism in any way. If all you’re executing is RoleA/RoleB, you could simply use the existing pre_tasks structure too, which will execute before any role tasks are run.

Hope that helps!

3

Hi James,

Thanks for the reply. However, my understanding is that the suggestion you made wrt to pre_tasks would only work if there was a playbook involved, which in our case, there isn’t. We only have two roles, and we want to publish both roles in Ansible Galaxy. RoleA’s meta/main.yaml looks as follows:

dependencies:

  • { role: roleB }

However, since Ansible always executes the dependencies first, there is no way for us to insert a “pre_task” before roleB is executed as I understand?

If so, the only other option is to create a dummy pre_tasks_role, and pollute Ansible Galaxy with it. This seems a bit wasteful, and inelegant. I suspect that more people will run into similar issues as they try to compose roles out of other roles?

cheers,
/Nuwan