Ansible role to set 'noop' i/o scheduler (CentOS 7)

README.md

Fixes

• make the IO scheduler configurable
• register grub_test to match the actual variable usage
• changed stdout to stdout_lines
• make block_devs work.
  • it looks gross, but previously interpreted block_devs.stdout_lines as a literal string

Ansible version: 2.7

gistfile1.txt

---
- name: test if grub configured for {{ io_scheduler }} i/o scheduler
  command: egrep -q 'elevator={{ io_scheduler }}' /boot/grub2/grub.cfg
  register: grub_test
  changed_when: no
  failed_when: grub_test.rc == 2

- name: configure grub for {{ io_scheduler }} i/o scheduler
  sudo: yes
  command: grubby --update-kernel=ALL --args=elevator={{ io_scheduler }}
  when: grub_test.rc == 1

- name: get list of block devices to test
  shell: ls /sys/block/ | egrep '^([shv]|xv])d[a-z]$'
  register: block_devs
  changed_when: no

- name: test if block device using {{ io_scheduler }} i/o scheduler
  shell: cat /sys/block/{{ item }}/queue/scheduler | egrep -q '\[{{ io_scheduler }}\]'
  with_items: "{{ block_devs.stdout_lines }}"
  register: sched_test
  changed_when: sched_test.rc == 1
  failed_when: sched_test.rc == 2

- name: set block device to use {{ io_scheduler }} i/o scheduler
  sudo: yes
  shell: echo '{{ io_scheduler }}' > /sys/block/{{ item }}/queue/scheduler
  with_items: "{{ block_devs.stdout_lines }}"
  when: sched_test.changed