Creating Reusable Playbooks¶
While it is possible to write a playbook in one very large file (and you might start out learning playbooks this way), eventually you’ll want to reuse files and start to organize things. In Ansible, there are three ways to do this: includes, imports, and roles.
Includes and imports (added in Ansible version 2.4) allow users to break up large playbooks into smaller files, which can be used across multiple parent playbooks or even multiple times within the same Playbook.
Roles allow more than just tasks to be packaged together and can include variables, handlers, or even modules and other plugins. Unlike includes and imports, roles can also be uploaded and shared via Ansible Galaxy.
Dynamic vs. Static¶
Ansible has two modes of operation for reusable content: dynamic and static.
In Ansible 2.0, the concept of dynamic includes was introduced. Due to some limitations with making all includes dynamic in this way, the ability to force includes to be static was introduced in Ansible 2.1. Because the include task became overloaded to encompass both static and dynamic syntaxes, and because the default behavior of an include could change based on other options set on the Task, Ansible 2.4 introduces the concept of
If you use any
include* Task (
include_role, etc.), it will be dynamic.
If you use any
import* Task (
import_tasks, etc.), it will be static.
include task (which was used for both Task files and Playbook-level includes) is still available, however it is now considered deprecated.
Differences Between Dynamic and Static¶
The two modes of operation are pretty simple:
- Dynamic includes are processed during runtime at the point in which that task is encountered.
- Ansible pre-processes all static imports during Playbook parsing time.
When it comes to Ansible task options like
tags and conditional statements (
- For dynamic includes, the task options will only apply to the dynamic task as it is evaluated, and will not be copied to child tasks.
- For static imports, the parent task options will be copied to all child tasks contained within the import.
Roles are a somewhat special case. Prior to Ansible 2.3, roles were always statically included via the special
roles: option for a given play and were always executed first before any other play tasks (unless
pre_tasks were used). Roles can still be used this way, however, Ansible 2.3 introduced the
include_role option to allow roles to be executed inline with other tasks.
Tradeoffs and Pitfalls Between Includes and Imports¶
import* has some advantages as well as some tradeoffs which users should consider when choosing to use each:
The primary advantage of using
include* statements is looping. When a loop is used with an include, the included tasks or role will be executed once for each item in the loop.
include* does have some limitations when compared to
- Tags which only exist inside a dynamic include will not show up in
- Tasks which only exist inside a dynamic include will not show up in
- You cannot use
notifyto trigger a handler name which comes from inside a dynamic include (see note below).
- You cannot use
--start-at-taskto begin execution at a task inside a dynamic include.
import* can also have some limitations when compared to dynamic includes:
- As noted above, loops cannot be used with imports at all.
- When using variables for the target file or role name, variables from inventory sources (host/group vars, etc.) cannot be used.
- Handlers using
import*will not be triggered when notified by their name, as importing overwrites the handler’s named task with the imported task list.
Regarding the use of
notify for dynamic tasks: it is still possible to trigger the dynamic include itself, which would result in all tasks within the include being run.
- Utilities modules
- Documentation of the
import*modules discussed here.
- Working With Playbooks
- Review the basic Playbook language features
- Using Variables
- All about variables in playbooks
- Conditionals in playbooks
- Loops in playbooks
- Best Practices
- Various tips about managing playbooks in the real world
- Galaxy User Guide
- How to share roles on galaxy, role management
- GitHub Ansible examples
- Complete playbook files from the GitHub project source
- Mailing List
- Questions? Help? Ideas? Stop by the list on Google Groups