This is a sample playbook which can be used to apply patches to a server and perform a reboot if one is required. This makes use of the handy needs-restarting command from the yum-utils / dnf-utils packages. The vars listed here are suggestions and can be updated to suit the requirements of your environment. For example, you could modify the code to specific apply certain updates from specific repos. This example playbook is used alongside Red Hat Satellite to apply O/S patches and Satellite Tools updates.

---
- name: Patch and reboot servers
  hosts: all
  vars:
    yum_name: "*"
    yum_state:  latest
    yum_enablerepo: "rhel-?-server-rpms,rhel-?-server-satellite-tools-6.?-rpms"
    yum_disablerepo: "*"
    yum_exclude: ""
    dnf_name: "*"
    dnf_state: latest
    dnf_enablerepo: "rhel-8-for-x86_64-appstream-rpms,rhel-8-for-x86_64-baseos-rpms,satellite-tools-6.?-for-rhel-8-x86_64-rpms"
    dnf_disablerepo: "*"
    dnf_exclude: ""
  tasks:

    - name: upgrade packages via yum
      yum:
        name={{ yum_name }}
        state={{ yum_state }}
        disablerepo={{ yum_disablerepo }}
        enablerepo={{ yum_enablerepo }}
        exclude={{ yum_exclude }}
      become: "yes"
      register: yumcommandout
      when:
        - (ansible_facts['distribution_major_version'] == '6') or
          (ansible_facts['distribution_major_version'] == '7')

    - name: Print errors if yum failed
      debug:
        msg: "yum command produced errors"
      when: yumcommandout is not defined

    - name: upgrade packages via dnf
      dnf:
        name={{ dnf_name }}
        state={{ dnf_state }}
        disablerepo={{ dnf_disablerepo }}
        enablerepo={{ dnf_enablerepo }}
        exclude={{ dnf_exclude }}
      become: "yes"
      register: dnfcommandout
      when:
        - ansible_facts['distribution_major_version'] == '8'

    - name: Print errors if dnf failed
      debug:
        msg: "dnf command produced errors"
      when: dnfcommandout is not defined

    - name: check to see if we need a reboot
      command: needs-restarting -r
      register: result
      ignore_errors: yes

    - name: display result
      debug:
        var: result.rc

    - name: Reboot Server if Necessary
      command: shutdown -r now "Ansible Updates Triggered"
      become: true
      async: 30
      poll: 0
      when: result.rc == 1

    # This pause is mandatory, otherwise the existing control connection
    # gets reused!
    # (https://gist.github.com/infernix/a968f23c4f4e1d6723e4)
    - name: Pausing to allow server to shutdown and terminate our SSH connection
      pause: seconds=30
      when: result.rc == 1

    - name: Wait for reboot to complete and SSH to become available
      local_action: wait_for host={{ inventory_hostname }} port=22
        state=started delay=30 timeout=600
      retries: 30
      delay: 10
      when: result.rc == 1