check_mode advertised but not supported

[acbk2b]

Issue

Background: --check allows users to run a playbook and see the proposed changes without actually executing them - this is essentially for guarding against accidental destructive configuration updates on critical network infrastructure.

All of the cp_gaia_* modules advertise support for Check Mode (i.e. supports_check_mode=True), however the main checkpoint.py module does not incorporate logic for check_mode and runs the associated /set-* or /add-* API regardless of whether the playbook is run with --check.

Fix

checkpoint.py contains the main API functions utilized by all upstream modules, specifically chkp_api_call and chkp_api_operation.
These functions handle several logical trees for different request types, as well as idempotency flows:

• Value exists and must be removed (i.e. state=absent)
• Value matches -> no change
• Value does not match -> run update
• Maestro special cases

To support check_mode, the logic in these functions needs to be updated to return early, with a diff, rather than running the /set-* or /add-* command.

# EXAMPLE: object exists and needs to be updated
# object exists and would be modified
if module.check_mode:
    after_preview = dict(before)
    after_preview.update(params_for_idempotency)
    return {
        api_call_object.replace('-', '_'): before,
        'diff': {'before': before, 'after': after_preview},
        "changed": True,
    }

Adding diff to the response allows the --diff flag to display the results for the user to view and confirm - this is a very important feature for reviewing changes

I am happy to help contribute a fix for this issue via pull-request.
Thanks!