openstack-ansible-lxc_hosts/tasks/lxc_container_btrfs.yml
Kevin Carter 2971b787ac Enable quota system and set qgroups
This change implements the machinectl quota system and qgroups when
they're enabled and available. This change is being implemented to
resolve an issue where machinectl based containers using a loopback file
system spam DMESG with the following:

* BTRFS error (device loop0): could not find root $INT

While various upstream sources say this error is benign[0], it raises
an inconsistency flag within the host system and is speculatively the
cause of our inconsistent read-only/Full-FS issues we've seen in the
integrated gate. Once the qgroups are properly setup the system will
remove the inconsistency flag and the message spam will stop.

* BTRFS info (device loop0): qgroup scan completed (inconsistency flag cleared)

To resolve this issue the quota system is being enabled by default
and unlimited qgroups are being setup to ensure we're not running
into file system limitations. This change essentially acknowledges
the built-in quota system and provides for the ability to set /
define specific quota (qgroup) options as necessary. While many
deployers may never use these options or this tooling, the role will
now properly set everything up should it ever be needed.

[0] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1651435
Closes-Bug: #1753790
Change-Id: I34a41ac8a9fe4419254284c83f4600efee274c04
Signed-off-by: Kevin Carter <kevin.carter@rackspace.com>
2018-05-15 14:19:11 +00:00

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---
# Copyright 2016, Rackspace US, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
- name: Create base container to use for BTRFS-backed containers
lxc_container:
name: "{{ lxc_container_base_name }}"
template: "download"
state: stopped
backing_store: "btrfs"
template_options: "{{ lxc_cache_download_template_options }}"
register: cache_download
retries: 3
delay: 10
until: cache_download|success
- name: Set the qgroup limits
block:
- name: Set the qgroup size|compression limits on machines
command: "btrfs qgroup limit {{ item }} /var/lib/lxc/{{ lxc_container_base_name }}"
changed_when: false
with_items:
- "-e {{ lxc_host_machine_qgroup_space_limit }}"
- "-c {{ lxc_host_machine_qgroup_compression_limit }}"
when:
- not lxc_host_machine_quota_disabled
rescue:
- name: Notice regarding quota system
debug:
msg: >-
There was an error processing the setup of qgroups. Check the system
to ensure they're available otherwise disable the quota system by
setting `lxc_host_machine_quota_disabled` to true.