Add configure-swap role

This is a role to configure swap and /opt on an infra host.

Originally we wrote this for devstack-gate with
Icd4e6d8ab84471ad06e69c3e0f9bac92776efc78.  It was ported into the
native devstack job with Iffe54fbccbccd68db08f79a1b51dd7f76dbff408.

This is really generic, and it's quite possible non-devstack jobs
would like to setup swap for jobs too, so o-z-j is a better home for
the role.

Change-Id: I0e9c846ace7fac8a1340746c6818fba6ec963018
changes/95/513595/1
Ian Wienand 5 years ago
parent 80237ba2dc
commit 1d01c6d3da
  1. 4
      .gitignore
  2. 11
      roles/configure-swap/README.rst
  3. 2
      roles/configure-swap/defaults/main.yaml
  4. 118
      roles/configure-swap/tasks/ephemeral.yaml
  5. 65
      roles/configure-swap/tasks/main.yaml
  6. 65
      roles/configure-swap/tasks/root.yaml

4
.gitignore vendored

@ -1,3 +1,7 @@
# Backup files
*~
\#*\#
# Unit test / coverage reports
.coverage
.tox

@ -0,0 +1,11 @@
Configure a swap partition
Creates a swap partition on the ephemeral block device (the rest of which
will be mounted on /opt).
**Role Variables**
.. zuul:rolevar:: configure_swap_size
:default: 8192
The size of the swap partition, in MiB.

@ -0,0 +1,2 @@
# Default swap partition/file size, in MiB
configure_swap_size: 8192

@ -0,0 +1,118 @@
---
# Configure attached ephemeral devices for storage and swap
- assert:
that:
- "ephemeral_device is defined"
- name: Set partition names
set_fact:
swap_partition: "{{ ephemeral_device}}1"
opt_partition: "{{ ephemeral_device}}2"
- name: Ensure ephemeral device is unmounted
become: yes
mount:
name: "{{ ephemeral_device }}"
state: unmounted
- name: Get existing partitions
become: yes
parted:
device: "{{ ephemeral_device }}"
unit: MiB
register: ephemeral_partitions
- name: Remove any existing partitions
become: yes
parted:
device: "{{ ephemeral_device }}"
number: "{{ item.num }}"
state: absent
with_items:
- "{{ ephemeral_partitions.partitions }}"
- name: Create new disk label
become: yes
parted:
label: msdos
device: "{{ ephemeral_device }}"
- name: Create swap partition
become: yes
parted:
device: "{{ ephemeral_device }}"
number: 1
state: present
part_start: '0%'
part_end: "{{ configure_swap_size }}MiB"
- name: Create opt partition
become: yes
parted:
device: "{{ ephemeral_device }}"
number: 2
state: present
part_start: "{{ configure_swap_size }}MiB"
part_end: "100%"
- name: Make swap on partition
become: yes
command: "mkswap {{ swap_partition }}"
- name: Write swap to fstab
become: yes
mount:
path: none
src: "{{ swap_partition }}"
fstype: swap
opts: sw
passno: 0
dump: 0
state: present
# XXX: does "parted" plugin ensure the partition is available
# before moving on? No udev settles here ...
- name: Add all swap
become: yes
command: swapon -a
- name: Create /opt filesystem
become: yes
filesystem:
fstype: ext4
# The default ratio is 16384 bytes per inode or so. Reduce that to 8192
# bytes per inode so that we get roughly twice the number of inodes as
# by default. This should still be well above the block size of 4096.
# We do this because we have found in at least a couple locations that
# more inodes is useful and is painful to fix after the fact.
opts: -i 8192
dev: "{{ opt_partition }}"
# Rackspace at least does not have enough room for two devstack
# installs on the primary partition. We copy in the existing /opt to
# the new partition on the ephemeral device, and then overmount /opt
# to there for the test runs.
#
# NOTE(ianw): the existing "mount" touches fstab. There is currently (Sep2017)
# work in [1] to split mount & fstab into separate parts, but for now we bundle
# it into an atomic shell command
# [1] https://github.com/ansible/ansible/pull/27174
- name: Copy old /opt
become: yes
shell: |
mount {{ opt_partition }} /mnt
find /opt/ -mindepth 1 -maxdepth 1 -exec mv {} /mnt/ \;
umount /mnt
# This overmounts any existing /opt
- name: Add opt to fstab and mount
become: yes
mount:
path: /opt
src: "{{ opt_partition }}"
fstype: ext4
opts: noatime
state: mounted

@ -0,0 +1,65 @@
---
# On RAX hosts, we have a small root partition and a large,
# unallocated ephemeral device attached at /dev/xvde
- name: Set ephemeral device if /dev/xvde exists
when: ansible_devices["xvde"] is defined
set_fact:
ephemeral_device: "/dev/xvde"
# On other providers, we have a device called "ephemeral0".
#
# NOTE(ianw): Once [1] is in our ansible (2.4 era?), we can figure
# this out more directly by walking the device labels in the facts
#
# [1] https://github.com/ansible/ansible/commit/d46dd99f47c0ee5081d15bc5b741e9096d8bfd3e
- name: Set ephemeral device by label
when: ephemeral_device is undefined
block:
- name: Get ephemeral0 device node
command: /sbin/blkid -L ephemeral0
register: ephemeral0
# If this doesn't exist, returns !0
ignore_errors: yes
changed_when: False
- name: Set ephemeral device if LABEL exists
when: "ephemeral0.rc == 0"
set_fact:
ephemeral_device: "{{ ephemeral0.stdout }}"
# If we have ephemeral storage and we don't appear to have setup swap,
# we will create a swap and move /opt to a large data partition there.
- include: ephemeral.yaml
static: no
when:
- ephemeral_device is defined
- ansible_memory_mb['swap']['total'] | int + 10 <= configure_swap_size
# If no ephemeral device and no swap, then we will setup some swap
# space on the root device to ensure all hosts a consistent memory
# environment.
- include: root.yaml
static: no
when:
- ephemeral_device is undefined
- ansible_memory_mb['swap']['total'] | int + 10 <= configure_swap_size
# ensure a standard level of swappiness. Some platforms
# (rax+centos7) come with swappiness of 0 (presumably because the
# vm doesn't come with swap setup ... but we just did that above),
# which depending on the kernel version can lead to the OOM killer
# kicking in on some processes despite swap being available;
# particularly things like mysql which have very high ratio of
# anonymous-memory to file-backed mappings.
#
# This sets swappiness low; we really don't want to be relying on
# cloud I/O based swap during our runs if we can help it
- name: Set swappiness
become: yes
sysctl:
name: vm.swappiness
value: 30
state: present
- debug: var=ephemeral_device

@ -0,0 +1,65 @@
---
# If no ephemeral devices are available, use root filesystem
- name: Calculate required swap
set_fact:
swap_required: "{{ configure_swap_size - ansible_memory_mb['swap']['total'] | int }}"
- block:
- name: Get root filesystem
shell: df --output='fstype' /root | tail -1
register: root_fs
- name: Save root filesystem
set_fact:
root_filesystem: "{{ root_fs.stdout }}"
- debug: var=root_filesystem
# Note, we don't use a sparse device to avoid wedging when disk space
# and memory are both unavailable.
# Cannot fallocate on filesystems like XFS, so use slower dd
- name: Create swap backing file for non-EXT fs
when: '"ext" not in root_filesystem'
become: yes
command: dd if=/dev/zero of=/root/swapfile bs=1M count={{ swap_required }}
args:
creates: /root/swapfile
- name: Create sparse swap backing file for EXT fs
when: '"ext" in root_filesystem'
become: yes
command: fallocate -l {{ swap_required }}M /root/swapfile
args:
creates: /root/swapfile
- name: Ensure swapfile perms
become: yes
file:
path: /root/swapfile
owner: root
group: root
mode: 0600
- name: Make swapfile
become: yes
command: mkswap /root/swapfile
- name: Write swap to fstab
become: yes
mount:
path: none
src: /root/swapfile
fstype: swap
opts: sw
passno: 0
dump: 0
state: present
- name: Add all swap
become: yes
command: swapon -a
- debug: var=swap_required
Loading…
Cancel
Save