ntp_config.yml

---
# This is a play, which is an element in the playbook.
# A playbook is a list of plays, and each play runs on
# a subset of hosts in the inventory. This specific play
# runs on all inventory devices. If there was a diverse set
# of hosts, such as routers, firewalls, and wireless LAN
# controllers, each one may have different NTP configuration
# syntax and could use different plays.
- name: "PLAY 1: Manage NTP configuration"
  hosts: "all"
  tasks:
    # This is the first task, and each play generally contains
    # a list of tasks. The task is a set of actions to execute
    # against each host specified within the play. This task
    # checks the data input quality, ensuring that the two
    # NTP servers are defined and are valid IPv4 addresses.
    # This task uses the "assert" module as a way of integrating
    # testing within a playbook.
    - name: "TASK 0: Validate NTP server IP addresses"
      assert:
        that:
          - "ntp_server1 is defined"
          - "ntp_server2 is defined"
          - "ntp_server1 | ipv4 == ntp_server1"
          - "ntp_server2 | ipv4 == ntp_server2"
        msg: "Malformed input; please check ntp_server values"

    # This is the second task. It logs into the Cisco IOS or
    # IOS-XE device using the "ios_config" module. The 'lines'
    # specified within that module are passed to the router, and
    # the NTP server values are substituted using {{ }} syntax.
    # The previous task verified that these servers were valid,
    # so the router CLI should not report any errors.
    # The "register" directive tells Ansible to "save" the
    # feedback from the module, which provides us a list of which
    # commands needed to be added (between 0 and 4 in this case),
    # whether there were any failures, and more.
    - name: "TASK 1: Apply NTP updates"
      ios_config:
        lines:
          - "ntp authenticate"
          - "ntp logging"
          - "ntp server {{ ntp_server1 }}"
          - "ntp server {{ ntp_server2 }}"
      register: "ntp_updates"

    # This is the third task. If any new changes were configured
    # on the router (for example, "ntp logging" had been accidentally
    # disabled before running the playbook), those delta commands
    # are printed to stdout so the user sees them. This only occurs
    # if there are changes due to the "when" directive. If the "when"
    # evaluates to false, the task is skipped. The task will only
    # be false when the registered variable from the previous task
    # does not define the "updates" subfield, which indicates no
    # changes were needed.
    - name: "TASK 2: Print changes if NTP config changed"
      debug:
        var: "ntp_updates.updates"
      when: "ntp_updates.updates is defined"
...