Network Automation with Ansible [NTP Server & Regex Example]

Mar262023

This playbook let’s you to replace existing NTP server on Cisco switch/router, by using regex.

2. Create an empty YAML file and name it ntp.yaml with below codes:

   # @author [Hawar Koyi] and [Roger Perkin]
   # @email [hawar@koyi.it]
   # @create date 2023-03-25 22:56
   # @desc [Network Automation - Add/replace NTP Server & Regex Example]
   # @Thanks to Roger Perkin - https://www.rogerperkin.co.uk
   
   #Start of codes
   ---
   - name: Configure NTP server by using regex
     hosts: Cisco
     connection: network_cli
     gather_facts: false
   
     tasks:
      #Get running config on the devices
      - name: Show Run on devices
        #Register/save data of show running-config as value "config"
        register: config
        ios_command:
           commands:
               #show running command on the devices
             - show run
   
      #Get current configured NTP server
      - name: Store current NTP line in running-config
       #Go through the running-config and find the start line with the word "ntp server"
       #-and (\S+) any mumber match a single character that is a non-whitespace. Continue with the next line.
        set_fact: _ntpServeres="{{ config.stdout[0] | regex_findall('^ntp server (\S+)', multiline=True) }}"
   
      #Remove old NTP server if detected
      - name: Remove old ntp server
        ios_config:
           lines:
               #show running command on the devices
             - "no ntp server {{ item }}"
           #Register/save data of show running-config as value "config"
        with_items: "{{ _ntpServeres }}"
   
       #Configure new NTP server
      - name: Config new NTP server
        ios_config:
           lines:
             - "ntp server {{ ntp_server_1 }}"
             - "ntp server {{ ntp_server_2 }}"
   
      #Saving the configurations on start-config
      - name: Save running-config to start-config
        ios_config:
          save_when: modified
   
     #EXTRA (Optional)
     #Display final results on the device run and start-config
     #Get retur output from show commands
      - name: Get retur output from show commands
        #Register data as value get_ntp
        register: get_ntp
        ios_command:
           commands:
             - "show run | include ntp"
             - "show start | i ntp"
     #Display final results for run and start-config on the devices. 
      - name: Show finally configurations on both start and running-config
        debug:
         var: get_ntp.stdout
   
   #End of codes
   
   
   

3. Create an empty text file and name it hosts with devices IP-addresses, vars and values for ntp_server variable.

   [Cisco]
   192.168.0.100
   192.168.xx.xx
   
   [Cisco:vars]
   ansible_connection=network_cli
   ansible_network_os=ios
   ansible_user=cisco
   ansible_password=cisco
   ansible_become=yes
   ansible_become_method=enable
   ansible_become_password=cisco
   
   ntp_server_1=193.150.22.36
   ntp_server_2=192.36.143.130

4. Finally run the playbook with this command

   ansible-playbook -i hosts ntp.yaml

   Results looks like the video below.

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