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= How To Contribute a driver to Cinder =
 
= How To Contribute a driver to Cinder =
  
=== Deadline for Kilo ===
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=== Deadline for Rocky ===
For clarification, a patch is considered a new driver when it's introducing a new protocol into the driver. For example, if your driver supports ISCSI, but your patch proposes support for FibreChannel, that's a new driver patch. Another example, if your driver has some proprietary protocol version 1 and your patch introduces proprietary protocol version 2, that's a new driver.
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For clarification, a patch is considered a new driver when it's introducing a new protocol into the driver. For example, if your driver supports iSCSI, but your patch proposes support for FibreChannel, that's a new driver patch.
  
Review the OpenStack dev mailing list [http://lists.openstack.org/pipermail/openstack-dev/2014-October/049512.html post] about his for more information.
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The deadline for new backend drivers, with working third party CI and no code review issues, will be June 7, 2018.
  
 
=== Third Party CI Requirement Policy ===
 
=== Third Party CI Requirement Policy ===
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=== Writing Code ===
 
=== Writing Code ===
* You must implement all of the methods that exist as [http://docs.openstack.org/developer/cinder/devref/drivers.html core features].
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* You must implement all of the methods that exist as [https://docs.openstack.org/cinder/latest/contributor/drivers.html core features].
  
* Your driver should not make any state changes. (e.g. make Cinder database calls). The [https://github.com/openstack/cinder/blob/master/cinder/volume/manager.py volume manager] is responsible for making state changes after the driver is done talking to the storage backend.
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* Your driver should not make any state changes. (e.g. make Cinder database calls). The [https://github.com/openstack/cinder/blob/master/cinder/volume/manager.py volume manager] is responsible for making state changes after the driver is done talking to the storage backend. Your driver should try not to read from database if possible.
  
* Unit tests for new code are required.  We're in the process of converting everything to use [http://www.voidspace.org.uk/python/mock/ mock] (rather than mox) for our unit tests.  Be sure when writing unit tests and setting up fakes to use mock, examples of it's usage can be found in the existing tests like cinder/tests/test_volume.py.
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* Unit tests for new code are required.
  
* Make sure you're not duplicating a configuration option that already exists. To verify this, you'll need to need look at the cinder/etc/cinder.conf.sample file. To generate this file:
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* Make sure you're not duplicating a configuration option that already exists. To verify this, you'll need to need look at the [https://docs.openstack.org/cinder/latest/configuration/block-storage/samples/cinder.conf.html cinder/etc/cinder.conf.sample file].
** Install [https://pypi.python.org/pypi/tox tox]
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** Every effort should be made to reuse common config options before introducing driver-specific ones.
** Run tox -egenconfig
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** If options are added, you will need to run "tox -e genopts" to update the opts.py file that is used to generate our configuration references.
  
 
* Make sure to follow the [http://docs.openstack.org/developer/hacking/ OpenStack Style Guide]. Very likely you'll get nit pick reviews otherwise, which is not productive either way.
 
* Make sure to follow the [http://docs.openstack.org/developer/hacking/ OpenStack Style Guide]. Very likely you'll get nit pick reviews otherwise, which is not productive either way.
  
* Use [http://docs.openstack.org/developer/oslo.i18n/usage.html log markers] by importing [http://git.openstack.org/cgit/openstack/cinder/tree/cinder/i18n.py cinder.i18n]
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* Cinder's [https://github.com/openstack/cinder/blob/master/cinder/volume/manager.py manager layer] will log useful information like failures from the driver that are raised. However, you're more than welcome to add additional logging, but please follow our [http://specs.openstack.org/openstack/openstack-specs/specs/log-guidelines.html logging guideline]. Use [http://docs.openstack.org/developer/oslo.i18n/usage.html log markers] by importing [http://git.openstack.org/cgit/openstack/cinder/tree/cinder/i18n.py cinder.i18n] so that log translations can be made.
  
 
=== Submitting Driver For Review ===
 
=== Submitting Driver For Review ===
* Do '''NOT''' bother the Cinder core team for reviews. We are aware of your patch being posted.
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When submitting your driver, please include a release note along with your patch. See the [http://docs.openstack.org/developer/reno/usage.html#creating-new-release-notes Reno Documentation] for details on how to generate new release notes.
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The release note should be something along the lines of:
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 +
---
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features:
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  - Added backend driver for ''vendor'' storage.
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* All new code should also be Python 3.5 compatible. Unit tests will be run with both python 2.7 and python 3.5, but additional runtime testing should be performed.
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* Do '''NOT''' bother the Cinder team for reviews. We are aware of your patch being posted.
  
 
* Make sure your commit message follows the [[GitCommitMessages|OpenStack project guidelines]].
 
* Make sure your commit message follows the [[GitCommitMessages|OpenStack project guidelines]].
  
* Make sure your driver has appropriate [[Cinder/tested-3rdParty-drivers|third party testing]] done.
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* Make sure your driver has appropriate [[Cinder/tested-3rdParty-drivers|third party testing]] done. It is required that your CI posts the [https://wiki.openstack.org/wiki/Cinder/tested-3rdParty-drivers#What_tests_do_I_use.3F necessary tests pass]. Since your driver is not yet merged, follow [https://wiki.openstack.org/wiki/Cinder/tested-3rdParty-drivers#How_do_I_run_my_CI_to_test_all_cinder_patches_with_my_driver_not_yet_merged.3F instructions] to have you unmerged driver properly tested.
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* Documentation is now kept in the openstack/cinder repo. At a minimum, please add a basic description of your driver and its configuration options under the [https://github.com/openstack/cinder/tree/master/doc/source/configuration/block-storage/drivers volume driver section of the Configuration reference].
  
 
*[http://docs.openstack.org/infra/manual/developers.html#development-workflow Post your review].
 
*[http://docs.openstack.org/infra/manual/developers.html#development-workflow Post your review].
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* Make sure there is documentation for your driver
 
* Make sure there is documentation for your driver
** Read and understand third party driver docs and work with OpenStack-Manuals on any concerns
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** Add a liaison name to https://wiki.openstack.org/wiki/Documentation/VendorDrivers after reading this [http://specs.openstack.org/openstack/docs-specs/specs/kilo/move-driver-docs.html spec]
** http://specs.openstack.org/openstack/docs-specs/specs/kilo/move-driver-docs.html
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** Refer to  [http://docs.openstack.org/contributor-guide/ Documentation Contributor Guide] on how to contribute.
** https://wiki.openstack.org/wiki/Documentation/HowTo
 
 
* Continue to be available on IRC and attend the weekly meetings in case questions come up.
 
* Continue to be available on IRC and attend the weekly meetings in case questions come up.
* Subscribe to receive bugs for yours driver! Cinder core will be triaging bugs and will tag bugs with the name of your company that are related to your driver. To subscribe:
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* Subscribe to receive bugs for your driver! The Cinder team will be triaging bugs and will tag bugs with the name of your company that are related to your driver. To subscribe:
 
** Go to https://bugs.launchpad.net/openstack/cinder/+bug
 
** Go to https://bugs.launchpad.net/openstack/cinder/+bug
 
** Click 'Subscribe to bug mail'
 
** Click 'Subscribe to bug mail'
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** Click tags
 
** Click tags
 
** With "match all tags" selected type in the field the name of your company.
 
** With "match all tags" selected type in the field the name of your company.
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[[Category: Cinder]]
 
[[Category: Cinder]]

Revision as of 20:45, 12 June 2018

How To Contribute a driver to Cinder

Deadline for Rocky

For clarification, a patch is considered a new driver when it's introducing a new protocol into the driver. For example, if your driver supports iSCSI, but your patch proposes support for FibreChannel, that's a new driver patch.

The deadline for new backend drivers, with working third party CI and no code review issues, will be June 7, 2018.

Third Party CI Requirement Policy

See third party CI wiki.

Before you write any code

  • Understand how Cinder works, what it's used for, why the other projects in OpenStack may or may not use it. Fully understand the difference between ephemeral storage on the Nova side versus the persistent storage offered by Cinder
  • Cinder offers a reference implementation that should be used as a model. The reference implementation driver file is cinder/volume/drivers/lvm.py, not to be mistaken for cinder/volume/driver.py which is the base class that all of the drivers inherit from. Note that there are a lot of options that show up there regarding iSCSI targets etc, but this gives you an idea of the expectations in terms of features that are implemented and some of the behaviors. I strongly recommend loading up devstack (you're going to need it to test your driver anyway) and play around with the default LVM. It's really important that you get a feel for how Cinder works and interacts with the other OpenStack projects before you get too far along.
  • You don't need a cinder spec for most drivers. You always need to submit a blueprint in Launchpad introducing your driver, so that it can be targeted for a release.
  • We have a development channel on freenode: #openstack-cinder. There are developers here round the clock, it's a great resource for you get started. Log in, ask questions, don't stare at code in isolation for a week... if you're stuck on something just ask. There's also no need to start off with "Can I ask a question"... you likely won't get a response. Just type in your question, that way anybody monitoring the channel that might know the answer can step in and answer.

Writing Code

  • You must implement all of the methods that exist as core features.
  • Your driver should not make any state changes. (e.g. make Cinder database calls). The volume manager is responsible for making state changes after the driver is done talking to the storage backend. Your driver should try not to read from database if possible.
  • Unit tests for new code are required.
  • Make sure you're not duplicating a configuration option that already exists. To verify this, you'll need to need look at the cinder/etc/cinder.conf.sample file.
    • Every effort should be made to reuse common config options before introducing driver-specific ones.
    • If options are added, you will need to run "tox -e genopts" to update the opts.py file that is used to generate our configuration references.
  • Make sure to follow the OpenStack Style Guide. Very likely you'll get nit pick reviews otherwise, which is not productive either way.
  • Cinder's manager layer will log useful information like failures from the driver that are raised. However, you're more than welcome to add additional logging, but please follow our logging guideline. Use log markers by importing cinder.i18n so that log translations can be made.

Submitting Driver For Review

When submitting your driver, please include a release note along with your patch. See the Reno Documentation for details on how to generate new release notes.

The release note should be something along the lines of:

---
features:
 - Added backend driver for vendor storage.
  • All new code should also be Python 3.5 compatible. Unit tests will be run with both python 2.7 and python 3.5, but additional runtime testing should be performed.
  • Do NOT bother the Cinder team for reviews. We are aware of your patch being posted.

After Your Driver Is Added

Congratulations! You're not done yet though. After your driver has been merged there are still some things that need to be done.

  • Make sure there is documentation for your driver
  • Continue to be available on IRC and attend the weekly meetings in case questions come up.
  • Subscribe to receive bugs for your driver! The Cinder team will be triaging bugs and will tag bugs with the name of your company that are related to your driver. To subscribe:
    • Go to https://bugs.launchpad.net/openstack/cinder/+bug
    • Click 'Subscribe to bug mail'
    • Click the radio button "are added and changed in any way"
    • Click checkbox 'Bugs must match this filter (...)"
    • Click tags
    • With "match all tags" selected type in the field the name of your company.