In the previous step we discovered and added the IP address of all our nodes to the file on NUC 2: /home/ansible/my-project/hosts

Our first Ansible playbook will be to update Ubuntu packages on all the worker nodes.

Purpose:

• Demonstrate a very useful playbook
• Update all our nodes to the latest code

From NUC 1, log in to the Ansible control node, NUC 2.

Even though each node receives its DNS information via DHCP, Ubuntu 22.04 will at times fail to resolve names. Rebooting solves the problem temporarily, but it will come back.

1. Create file /home/ansible/my-project/disable-dns-stub.yml

   • disable-dns-stub.yml

     ---
     - name: Disable DNS stub listener
       hosts: nodes
       remote_user: ansible
       become: true
       tasks:
         - name: Disable DNS stub listener
           ini_file: dest=/etc/systemd/resolved.conf section=Resolve option=DNSStubListener value=no backup=yes
           tags: configuration
         - name: Restart NetworkManager
           systemd:
             name: NetworkManager
             state: restarted
         - name: Restart systemd-resolved
           systemd:
             name: systemd-resolved
             state: restarted
         - name: daemon-reload
           systemd:
             daemon_reload: true

2. Run the playbook: ansible-playbook -i hosts disable-dns-stub.yml

1. Create file /home/ansible/my-project/update.yml

   • update.yml

     ---
     - hosts: nodes
       become: true
       become_user: root
       tasks:
         - name: Update apt repo and cache on all Debian/Ubuntu boxes
           apt: update_cache=yes force_apt_get=yes cache_valid_time=3600
     
         - name: Upgrade all packages on servers
           apt: upgrade=dist force_apt_get=yes
     
         - name: Check if a reboot is needed on all servers
           register: reboot_required_file
           stat: path=/var/run/reboot-required get_md5=no
     
         - name: Reboot the box if kernel updated
           reboot:
             msg: "Reboot initiated by Ansible for kernel updates"
             connect_timeout: 5
             reboot_timeout: 300
             pre_reboot_delay: 0
             post_reboot_delay: 30
             test_command: uptime
           when: reboot_required_file.stat.exists

2. Run the playbook: ansible-playbook -i hosts update.yml

Congratulations you just updated your nodes! Next is your second Ansible playbook - Ansible Playbook - CMOS.

Set the ethernet interface to be “optional” on the nodes so they will boot faster; they normally wait for the network to come up on the wired interface. Since we are on WiFi only, the interface will never come up.

Steps:

1. Create file /home/ansible/my-project/ethernetoptional.yml

   • ethnetoptional.yml

     ---
     - hosts: nodes
       become: true
       become_user: root
       tasks:
         - name: Set ethernet interface to optional
           lineinfile:
             path: /etc/netplan/00-installer-config.yaml
             insertafter: "dhcp4: true"
             line: "      optional: true"
         - name: Apply netplan
           command: netplan apply
           ignore_errors: true

2. Test the playbook
   • ansible-playbook -i hosts ethernetoptional.yml

Sometimes in my Lab testing I find a NUCs that seem slowing or become unresponsive. This can actually be due to a poor WiFi connection!

1. Create the playbook check-wifi.yml

   • check-wifi.yml

     ---
     - name: Check wifi strength
       hosts: clients
       remote_user: ansible
       become: true
       tasks:
         - name: Make sure wireless-tools is installed
           apt:
             name: wireless-tools
             state: present
         - name: Gather wifi strength
           shell: "iwconfig | grep Quality"
           register: wifi
           changed_when: false
         - name: Display wifi strength
           debug:
             msg: "{{ item }}"
           with_items: "{{ wifi.stdout_lines }}"
         - name: Calculate wifi strength
           set_fact:
             strength: "{{ wifi.stdout | regex_search(regexp, '\\1') }}"
           vars:
             regexp: 'Quality=([0-9]+)/70'
         - name: Show value
           debug:
             msg:
               - "{{ strength[0] }}/70 = {{( ( (strength[0] | int) / 70) * 100 ) | int }}%"

2. Run it: ansible-playbook -i hosts check-wifi.yml
3. If all the NUCs are in the same place but one is much weaker than the others
   • check the antennas are connected to the Wifi card
   • does a different wifi card improve the connection?