Adding hooks to your Ansible roles
When writing Ansible roles, it pays to leave room for inserting tasks (like callbacks or hooks).
For example, in [role]/tasks/main.yml:
- task 1
- task 2
<--- you want to allow something to happen here.
- task 3In order to do that, add an empty file in (for example)[role]/hooks/empty.yml, and add an insert statement like the following:
- include: "{{ hook_variable | default(lookup('pipe', 'pwd') ~ '/hooks/empty.yml') }}"Where hook_variable is a full path to the tasks file to include.
An example that uses the playbook_dir:
hook_variable: "{{ playbook_dir }}/hooks/tasks-file.yml" The reason the default filter is used, is because it's required to point to an existing file with include. The above example uses the lookup plugin to find your role's path.
Written by Ramon de la Fuente
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1 Response
Excellent idea. My approach was to have only the variable in the include statement, no default, and then instead have a when condition to enable the inclusion only when the variable is defined. This hook in our generic deployment flow saved the day for one of my colleagues today.
- name: Run tasks pointed at by pre_start_hook if defined
include: "{{ pre_start_hook }}"
when: pre_start_hook is definedHave a fresh tip? Share with Coderwall community!
