playbook_patch_RHEL.yml

### Update systems 'CentOS' or 'Red Hat Enterprise Linux'
### by Mark Nguyen
### Reference: Yogesh Mehta(youtube)
### 10/2018
---
- hosts: linux1rhel 
  become_user: root
  serial: 2
  tasks:
    # check if apache is running
    - name: verify application/database processes
      shell: if ps -elf | grep 'apache|http' | grep =v grep > /dev/null; then echo 'process for webserver is running'; else echo 'Webserver process is not running'; fi
      ignore_errors: true
      register: app_process_check

    # decision point: fil==quit
    - name: upgrade all packages on rhel servers
      yum: name="kernel" state=latest
      retries: 3
      when: app_process_check.stdout == "Webserver process is not running" and ansible_distribution == 'CentOS' or ansible_distribution == 'Red Hat Enterprise Linux'
      register: yum_update

    # check if update happened and reboot occured
    - name: check if reboot required after update
      shell: KERNEL_NEW=$(rpm -q --last kernel | head -1 | awk '{print $1}' | sed 's/kernel.//'); KERNEL_NOW=$(uname -r); if test $KERNEL_NEW != $KERNEL_NOW; then echo "reboot_needed"; else echo "reboot_not_needed"; fi
      ignore_errors: true
      register: reboot_required

    # restart the system
    - name: restart_system
      command: shutdown -r +1 "System is about to reboot after patching..."
      async: 0
      poll: 0
      when: reboot_required.stdout = "reboot_needed"
      register: reboot_started
      ignore_errors: true

    # Wait for 3 minutes for system to come up
    - name: pause for 180 secs
      pause: 
        minutes: 3

    # Verify that system came up and responded to ssh command
    - name: checki if ssh is responding
      local_action:
        module: wait_for
          host={{ inventory_hostname }}
          port=22
          delay=15
          timeout=300
          state=started
      when: reboot_started|changed