Using host facts to diagnose failures

Some execution failures derive from the state of the target machine. The most common problem of this kind is the case where Ansible expects a file or variable to be present, but it's not.

Sometimes, it can be enough to print the machine facts to find the problem.

To do so, we need to create a simple playbook, called print_facts.yaml, which contains the following content:

---
- hosts: target_host
  tasks:
    - name: Display all variables/facts known for a host
      debug:
        var: hostvars[inventory_hostname]

This technique will give you a lot of information about the state of the target machine during Ansible execution.