DevOps Practitioner · Module 5: Ansible and configuration management · Lab
Apply Idempotent Service Config on Owned Lab Targets
50 min hands-on · Core
One or two learner-owned lab targets (local VMs or containers) plus a control machine; a static inventory containing only lab machines.
Local guide: run the steps below on your own machine in order, then check the validation list.
Objectives
- Write a role that converges a service config from any starting state
- Prove changed-then-ok across two consecutive runs
- Roll back a bad change by reapplying the previous variables
Step 1
Write the converging role
Write a role managing a service config file with templates and a handler restart. Review it with check mode and diff limited to one canary target before applying.
Step 2
Prove the second run is silent
Apply to the group, then run again immediately and quote the all-ok output with zero changes. Any change on the second run is a task defect: fix the state test and repeat.
Step 3
Break and restore
Apply a bad variable, watch the canary check catch it or the service complain, then restore by reapplying the previous variables and verify service health.
How to confirm it worked
- Check-mode preview quoted before the first apply
- Second run quoted all-ok with zero changes
- Bad change restored via reapply with service verified
- Inventory contains only learner-owned machines