cinder-volume-driver

This Docker volume driver makes OpenStack Block Storage volumes (aka Cinder volumes) available as Docker volumes.

It was written to circumvent a big issue found in rexray/cinder: it uses the device name of volume attachments returned by OpenStack API whereas this field is guessed by OpenStack and thus shall not be trusted. From a higher-level, this means Block Storage volumes could be mixed up when attached/mounted by rexray, leading to the wrong containers writing to the wrong volumes. This has been a source of service disruption, data loss, etc... for one of my client.

Since rexray/cinder uses libstorage which is meant to potentially run on another server than the one which got volume attached/mounted, the above issue can't be easily fixed. Also, the code of libstorage and rexray is a bit complex and thus hard to debug.

Moreover, this plugin adds new features not found in rexray/cinder like:

• The ability to specify the uid/gid and filemode to apply to volumes' root folder after formatting them ;
• The ability to specify the ID of a snapshot to use to create a volume ;
• And others volume options (see below).

How to install?

You can install this plugin with:

$ docker plugin install --alias cinder akerouanton/cinder:v0.1 <env-vars>

Supported env vars

Here's the list of env vars supported by this plugin:

Name	Default Value	Description
OS_AUTH_URL		See [1].
OS_USERNAME		See [1].
OS_USERID		See [1].
OS_PASSWORD		See [1].
OS_PASSCODE		See [1].
OS_TENANT_ID		See [1].
OS_TENANT_NAME		See [1].
OS_DOMAIN_ID		See [1].
OS_DOMAIN_NAME		See [1].
OS_APPLICATION_CREDENTIAL_ID		See [1].
OS_APPLICATION_CREDENTIAL_NAME		See [1].
OS_APPLICATION_CREDENTIAL_SECRET		See [1].
OS_PROJECT_ID		See [1].
OS_PROJECT_NAME		See [1].
OS_REGION_NAME		Name of the OpenStack region where Compute & Block Storage resources are located.
DEFAULT_SIZE	20	Default volume size in GB.
VOLUME_PREFIX		Name prefix of volumes managed by this plugin.
LOG_LEVEL	debug	Log level (either: trace, debug, info, warn, error, fatal, panic).
DEBUG		Enable /pprof/trace endpoint when the value is not empty.

[1] https://docs.openstack.org/python-openstackclient/pike/cli/man/openstack.html#environment-variables

Supported volume options

Here's the list of options you can pass when creating a volume :

Name	Default Value	Description
size	The value of DEFAULT_SIZE env var	The size of the underlying Block Storage volume.
availability_zone	N/A	AZ where the underlying Block Storage volume should be created.
consistency_group	N/A	See https://docs.openstack.org/cinder/latest/admin/blockstorage-consistency-groups.html
description	N/A	Description of the underlying Block Storage volume.
source_snapshot	N/A	ID of the Block Storage snaphost used to create the volume.
source_backup	N/A	ID of the Block Storage backup used to create the volume.
volume_type	N/A	Block storage volume type.
uid	0	Default UID set on the volume root dir after formatting the volume.
gid	0	Default GID set on the volume root dir after formatting the volume.
mode	0750	Default file mode set on the volume root dir after formatting the volume.

For instance, if you want to define the size of a volume and the source snapshot the volume should be created from, with Docker CLI:

$ docker volume create -d cinder -o size=40 -o source_snapshot=<snapshot-uuid> test

And with docker-compose:

services:
  # ...

volumes:
  test:
    name: test
    driver: cinder
    driver_opts:
      size: 40
      source_snapshot: "<snapshot-uuid>"

How to work on this?

You can create a new devel plugin release with make plugin and you can install it with make install (you have to set env vars in .env file first).

To release a new version you have to use: PLUGIN_VERSION=vX.Y make release.