LEARN. PRACTICE. GROW.Concept and mechanism
A useful playbook describes conditions required for the outcome, including dependencies an administrator might have created manually. Running it on an old host can hide that preparation. Under EX294 objectives, playbooks are applied to fresh systems and configurations must persist after reboot. Therefore, distinguish error-free execution, intended state, and reconstruction of that state at boot. A currently active mount does not prove persistent configuration exists. A directory readable by a group also needs search permission to allow traversal. Its mode should represent access requirements without adding write merely to remove an error.
Guided application
In a fictional batch project, reproduce configuration on a disposable host and compare the initial execution with a repeat. A state module can avoid unnecessary changes; a command does not become idempotent simply by using register. Creates can prevent repetition when a reliable marker exists and is created only after validated success. That marker does not replace validation of the migration it represents. In a registered result, rc, stdout, and changed mean different things. Document acceptable codes before building conditions. Facts are observations too: ansible_date_time gathered at startup does not advance like a live clock. To measure a later phase, collect time evidence appropriate to that moment.
The mount works before reboot; rehearsal ends only after confirming the mounted resource afterward.
Common pitfalls
Prepared host as universal proof; changed as success; marker created before validation.
Related topics: Inventories, variables, and configuration · Access and execution environment · Git, dev containers, and rehearsals
Represent prerequisites and verify the outcome operations actually needs.
Reference: EX294 Advanced System Administrator in Ansible objectives · EX294 current objectives inspected 2026-09-30; RHCE in Ansible framework effective 2026-05-11; booking product version not publicly pinned