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This is generated using: $ tox -e move-implemented-specs -- pike -v Change-Id: I4f3e159430dbe7146e98f93645d8f6be06acb097
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This work is licensed under a Creative Commons Attribution 3.0 Unported
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License.
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http://creativecommons.org/licenses/by/3.0/legalcode
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=======================================
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Allow an attached volume to be extended
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=======================================
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https://blueprints.launchpad.net/nova/+spec/nova-support-attached-volume-extend
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Problem description
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===================
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Currently a volume size extension requires that a volume be
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in the available state. This requires an attached volume to be detached
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from a server before the volume can be extended in size. This requires that
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a volume be brought offline from the standpoint of the application
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using the volume.
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Use Cases
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---------
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A end user wants to increase the size of a volume that is currently attached
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to a server.
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Proposed change
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===============
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Nova will be listening for attached volume extend notification from Cinder
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using the existing external-events API endpoint.
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When the notification is received, Nova will trigger a rescanning of device
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on the host using os-brick to discover the change in volume size.
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The os-brick library already supports volume size extension
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through the Connector API method called "extend_volume" since 0.8.0.
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The initial implementation aims to support virt drivers using os-brick
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such as libvirt and hyper-v.
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The end user will have to perform a partition and/or filesystem resize
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in the guest to fully benefit from the new volume size.
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Capabilities discovery and error handling if the compute host
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does not support the extend volume operation are being discussed on the
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openstack-dev mailinglist. [1]_
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Alternatives
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------------
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None
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Data model impact
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-----------------
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None
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REST API impact
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---------------
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A new microversion is required because a new external-event type
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will be added: volume-extended.
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Proposed JSON request body for the new "volume-extended" event::
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{
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"events": [
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{
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"name": "volume-extended",
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"server_uuid": "3df201cf-2451-44f2-8d25-a4ca826fc1f3",
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"tag": "0e63d806-6fe4-4ffc-99bf-f3dd056574c0"
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}
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]
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}
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Definition of fields:
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name
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Name of the event. ("volume-extended" for this feature).
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tag
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Volume UUID being extended.
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server_uuid
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Server UUID to which the extended volume is attached.
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Proposed JSON response body for the new "volume-extended" event::
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{
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"events": [
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{
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"name": "volume-extended",
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"status": "completed",
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"code": 200,
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"server_uuid": "3df201cf-2451-44f2-8d25-a4ca826fc1f3",
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"tag": "0e63d806-6fe4-4ffc-99bf-f3dd056574c0"
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}
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]
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}
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Definition of fields:
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name
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Name of the event. ("volume-extended" for this feature).
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status
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Event status. Possible values:
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* "completed" if accepted by Nova
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* "failed" if a failure is encountered
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code
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Event result code. Possible values:
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* 200 means accepted
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* 404 means the server could not be found
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* 422 means the event cannot be processed because the instance was found
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to not be associated to a host.
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server_uuid
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Same value as provided in original request.
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tag
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Same value as provided in original request.
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Possible HTTP response codes:
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* The HTTP response code 200 is returned on success.
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* The HTTP response code 207 is returned if any event fails with 422 code.
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* The HTTP response code 400 is returned on a bad request.
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* The HTTP response code 401 is returned if request is unauthorized. (keystone)
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* The HTTP response code 403 is returned if request is forbidden. (policy)
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* The HTTP response code 404 is returned if no server could be found.
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Security impact
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---------------
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None
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Notifications impact
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--------------------
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None
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Other end user impact
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---------------------
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The end user will be able to extend their volumes without having
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to detach them.
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The end user will have to perform a partition and/or filesystem resize
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to fully benefit from the new volume size.
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Performance Impact
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------------------
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None
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Other deployer impact
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---------------------
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None
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Developer impact
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----------------
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Driver owners may want to enable this feature in their driver.
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Implementation
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==============
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Assignee(s)
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-----------
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Primary assignee:
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mgagne
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Other contributors:
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manas-mandlekar
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shyvenug@in.ibm.com
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Work Items
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----------
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* Add new external-event type and new microversion
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* Call virt driver so guest detects the new volume size
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* Call the os-brick extend_volume API to trigger the host kernel size
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information to be updated on the attached host
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Dependencies
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============
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* The Cinder API changes to allow extend of an attached volume
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Testing
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=======
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Add Tempest test where the size of a volume attached to a server is extended
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and the new size can be discovered on the host.
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Documentation Impact
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====================
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Update the compute API reference documentation with new volume-extended event.
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References
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==========
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This blueprint is in conjunction with the work being done on the Cinder
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extend attached volume. [2]_
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.. [1] http://lists.openstack.org/pipermail/openstack-dev/2017-April/115292.html
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.. [2] https://review.openstack.org/#/c/453286/
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History
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=======
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.. list-table:: Revisions
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:header-rows: 1
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* - Release Name
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- Description
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* - Pike
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- Introduced
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