Debugging Ansible tips

ansible_advanced.md

Debugging Options

To debug (using print statements), one has 2 options

Debug the Module

• The module files are located inside ansible/module_utils/module_name/ ie: ansible/module_utils/k8s/
• The parameters given to a specific task are stored in the self.params
• self.params gets the values assigned outside the module (from the Module System)
• Adding any print statements, will result in the task failing, so after debugging ensure no prints are still existent

Debug the Module System

• The module systems files are located in ansible/module_utils/ (ie: basic.py ) and ansible/module_utils/system/ (ie: setup.py)
• Modifying those files won't help at all, as they will

1. Fail the task with the message The following modules failed to execute: setup
2. Avoid from reaching the other non-system debug points.

Use Case

In my debugging session, I used from_yaml_all filter, instead of from_yaml_all | list which resulted in the resource_definition param being the generator object's string, thus I got the error described in this issue.
The use of list filter forces the from_yaml_all to return the output as a list, that can be justified by the fact that ansible is written in Python, and it depends on the output of yaml.load_all() which should be loaded with list(), following this answer.

Template Processing

• Jinja whitespace templating could be further controlled based on this SO Answer.