cinder-specs/specs/juno/pure-iscsi-volume-driver.rst

Cinder volume driver for Pure Storage FlashArray

Include the URL of your launchpad blueprint:

https://blueprints.launchpad.net/cinder/+spec/pure-iscsi-volume-driver

The purpose of this spec is to add a Cinder volume driver for Pure Storage FlashArray. It will support the iSCSI protocol and will include at least the minimum set of features required by the Juno release. We will also set up automated CI testing on an OpenStack cluster maintained by Pure Storage in accordance with the third party CI requirement policy.

Pure Storage builds all-flash storage arrays. The active/active controller architecture is based on the Purity Operating Environment and providing an adaptive metadata fabric that is scalable, granular to 512B, and protected.

Problem description

Currently, the Pure Storage FlashArray cannot be used a block storage backend in an OpenStack environment.

Use Cases

Proposed change

Add a Pure Storage FlashArray Cinder driver to the OpenStack Cinder package.

The Pure Storage driver will leverage a thin Python REST client library. The client library interacts with the REST service hosted on the FlashArray to perform array management and satisfy Cinder driver API requirements.

Control Flow

                   +------------------+
                   |     Cinder +     |
                   |   Cinder Volume  |
                   +--------+---------+
                            |
                            v
                   +------------------+
                   |    Pure Driver   |
                   |                  |
                   +--------+---------+
                            |
                            v
                   +------------------+
                   | Pure REST Client |
                   |                  |
                   +--------+---------+
                            |
                            v
                   +------------------+
                   | Pure REST Server |
                   |   (FlashArray)   |
                   +------------------+

The Cinder driver will make use of REST client APIs to support:

• Volume Create/Delete
• Volume Attach/Detach
• Snapshot Create/Delete
• Create Volume from Snapshot
• Get Volume Stats
• Copy Image to Volume
• Copy Volume to Image
• Clone Volume
• Extend Volume

In addition to the delivery of the driver implementation, the proposed change includes the addition of unit tests for the driver. Pure Storage will create dedicated Jenkins jobs to support CI and Tempest test execution on a Devstack virtual machine to continuously prove functionality of the driver.

Alternatives

None.

Data model impact

None.

REST API impact

None.

Security impact

The only security related aspect is that an API token is required by the driver to leverage the REST client and authenticate against the REST API.

The API token must be specified in the cinder.conf configuration file.

Notifications impact

None.

Other end user impact

The impact of this change is that OpenStack Cinder will have support for using a Pure Storage FlashArray as a backing block storage device.

Performance Impact

None.

Other deployer impact

The configuration needed to leverage the Pure Storage driver includes:

• volume_driver - Specifies the Pure Storage FlashArray driver module.
• pure_target - The address of the FlashArray storage target.
• pure_api_token - An API token created on the FlashArray to authenticate REST clients, which the driver will make use of.

And optionally:

• pure_host_name - The name of a host object on the FlashArray to associate with IQNs and volume connections. This defaults to the name "OpenStack" if not provided.

Developer impact

None.

Implementation

Assignee(s)

Primary assignee:

victor-ying <victor.ying@purestorage.com>

Other contributors:

wes-w <wes@purestorage.com> zach-olstein <zach.olstein@purestorage.com>

Work Items

• Complete Cinder Pure Storage driver implementation.
• Complete Cinder Pure Storage driver unit tests.
• Pass automated Tempest tests to prove functionality.
• Integrate Devstack VM and Jenkins job into Pure Storage Jenkins system.

Dependencies

The driver has a dependency on a REST client library provided by Pure Storage that allows developers to easily build Python applications built on REST API functionality.

The library is currently not available as a pip-installable Python package, so the library module will be committed along with the driver implementation.

Testing

As mentioned in work items, the delivery of the driver will be accompanied by a suite of unit tests for the driver (that use Mock to isolate driver code from the FlashArray). Additionally, continuous integration through Jenkins and automated Tempest test runs are required for the driver to be accepted.

Documentation Impact

Pure Storage should be listed as having a supported Cinder driver on the CinderSupportMatrix: https://wiki.openstack.org/wiki/CinderSupportMatrix

References

None.