How to create a shared playbook?

Question

Ansible

There are several groups of servers, conditionally alfa, beta, gamma.
Each of them has its own playbook with separate and common tasks, such as:
alfa.yml
- hosts: alfa
- roles:
- common
- nginx
beta.yml
- hosts: beta
- roles:
- common
- database
How to create such a meta-playbook , which would run all the others? It is clear that you can make include, but then they will be executed step-by-step, and not in parallel. Or I'm wrong?

Answer 1

they are now performed by you step by step

Answer 2

If the question is still relevant, then ansible 1.8+ has such an opportunity.
Asynchronous Actions and Polling
docs.ansible.com/ansible/playbooks_async.html