Perhaps other might find this useful.  I'm using it to update SL machines.

-- 
Orion Poplawski
Manager of NWRA Technical Systems          720-772-5637
NWRA, Boulder/CoRA Office             FAX: 303-415-9702
3380 Mitchell Lane                       [log in to unmask]
Boulder, CO 80301                 https://urldefense.proofpoint.com/v2/url?u=https-3A__www.nwra.com_&d=DwICaQ&c=gRgGjJ3BkIsb5y6s49QqsA&r=gd8BzeSQcySVxr0gDWSEbN-P-pgDXkdyCtaMqdCgPPdW1cyL5RIpaIYrCn8C5x2A&m=xxpKxxHU-BcBo4xZ080YcpBdRnfGhzZ6q_hwc3ksN7k&s=D9K--yjoDCjyybHBGdr9zueueYKVBPsx0l-LaJXiTzU&e=



#!/usr/bin/ansible-playbook
---
- hosts: sl-7*
  vars:
    releasever: 7.5
  tasks:
  - name: "Get current release version"
    slurp:
      src: /etc/yum/vars/slreleasever
    register: current_slreleasever
  - block:
    - name: "Set slreleasever"
      copy:
        dest: /etc/yum/vars/slreleasever
        content: "{{ releasever }}{{'\n'}}"
    - name: "Clear yum cache"
      file:
        path: /var/cache/yum/x86_64
        state: absent
    - name: "Upgrade"
      yum:
        name: '*'
        releasever: "{{ releasever }}"
        state: latest
    when:
    - current_slreleasever.content | b64decode != releasever ~ "\n"
    - current_slreleasever.content | b64decode != "7x\n"