On the web you can find many tips about how to update CentOS/RHEL linux systems. Some of them are quite old and do not leverage new features available in recent Ansible versions, other has some issues or do not provide a nice way to display what’s going on.

Recently I’ve spent some time tuning ansible playbook to develop a nice way to update my RedHat family systems.

The playbook does the following:

• First, it checks if there are any packages to be updated and displays them.
• Next, it starts the update.
• After that it installs (if necessary) yum-utils package that provides needs-restarting command which tells us if the system reboot is required after the update.
• Then it reboots host if necessary and wait for it to come back online.
• At the end it displays a message with number of seconds that it took to reboot.

Below you will find tasks from the playbook (I do not post whole playbook as you can have your own requirements e.g. for serialization or host group):

- name: check packages for updates
  shell: yum list updates | awk 'f;/Updated Packages/{f=1;}' | awk '{ print $1 }'
  changed_when: updates.stdout_lines | length > 0
  args:
    warn: false
  register: updates

- name: display count
  debug:
    msg: "Found {{ updates.stdout_lines | length }} packages to be updated:\n\n{{ updates.stdout }}"

- when: updates.stdout_lines | length > 0
  block:
    - name: install updates using yum
      yum:
        name: "*"
        state: latest

    - name: install yum-utils
      package:
        name: yum-utils

    - name: check if reboot is required
      shell: needs-restarting -r
      failed_when: false
      register: reboot_required
      changed_when: false

- when: updates.stdout_lines | length > 0 and reboot_required.rc != 0
  block:
    - name: reboot the server if required
      shell: sleep 3; reboot
      ignore_errors: true
      changed_when: false
      async: 1
      poll: 0

    - name: wait for server to come back after reboot
      wait_for_connection:
        timeout: 600
        delay: 20
      register: reboot_result

    - name: reboot time
      debug:
        msg: "The system rebooted in {{ reboot_result.elapsed }} seconds."

I hope you find it useful :)