Add more granularity to stackl ansible invocation #195
Description
Description of feature
As-is you can define a playbook in an image used by Stackl. In this playbook you can define your hosts. However, since the dynamic inventory groups hosts and variables under groups named after the Stackl service, and since fr's can be used by multiple services, you do not always know which host you want to execute a playbook against.
In the past this has been mitigated by defining all as hosts, but when multiple services are added in a stack-instance, you may not want to execute against all hosts but instead against a certain group.
Only way to circumvent this issue is by executing a role ad-hoc, which comes with its own limitations (fr must have the same name as the role, and you can only execute a role ad-hoc and nothing else)
Purpose of this new feature
The purpose of this feature is to find a way to make an Ansible invocation more flexible and more userfriendly, preferably without having to change an image's content (change the playbook in an image). It should also make the way Stackl executes an Ansible job more transparent to those who do not want to dive into the Stackl source code.