Question

A data center automation engineer maintains Cisco Nexus 9000 switches using Ansible with the cisco.nxos collection. Before applying a large VLAN and interface configuration change to production leaf switches, the engineer wants to preview exactly which tasks would report a change WITHOUT altering any device state, and also wants confidence that re-running the playbook after a successful apply will report no further changes. Which combination of Ansible characteristics satisfies both requirements?

Accepted Answer

Run the playbook with --check mode to preview changes, relying on the modules' idempotency so a re-run against an already-configured device reports 'ok' instead of 'changed'

Answer

Run the playbook with --forks 1 to serialize execution, which guarantees no device changes occur during the first pass

Answer

Use the nxos_command module with a 'when: false' conditional so commands are queued but never sent to the device

Answer

Enable --diff mode alone, since diff output prevents the modules from committing configuration to the running-config