OpenStack Nova Specifications¶
This git repository is used to hold approved design specifications for additions to the Nova project. Reviews of the specs are done in gerrit, using a similar workflow to how we review and merge changes to the code itself. For specific policies around specification review, refer to the end of this document.
The layout of this repository is:
Where there are two sub-directories:
specs/<release>/approved: specifications approved but not yet implemented specs/<release>/implemented: implemented specifications
The lifecycle of a specification¶
Developers proposing a specification should propose a new file in the
approved directory. nova-specs-core will review the change in the usual
manner for the OpenStack project, and eventually it will get merged if a
consensus is reached. At this time the Launchpad blueprint is also approved.
The developer is then free to propose code reviews to implement their
specification. These reviews should be sure to reference the Launchpad
blueprint in their commit message for tracking purposes.
Once all code for the feature is merged into Nova, the Launchpad blueprint is marked complete. As the developer of an approved specification it is your responsibility to mark your blueprint complete when all of the required patches have merged.
Periodically, someone from nova-specs-core will move implemented specifications
approved directory to the
implemented directory. Whilst
individual developers are welcome to propose this move for their implemented
specifications, we have generally just done this in a batch at the end of the
release cycle. It is important to create redirects when this is done so that
existing links to the approved specification are not broken. Redirects aren’t
symbolic links, they are defined in a file which sphinx consumes. An example
tox -e move-implemented-specs target at the end of each
release to automatically move completed specs and populate the
redirects file for that release. For example:
tox -r -e move-implemented-specs -- --dry-run --verbose newton
This directory structure allows you to see what we thought about doing,
decided to do, and actually got done. Users interested in functionality in a
given release should only refer to the
You can find an example spec in
Additionally, we allow the proposal of specifications that do not have a developer assigned to them. These are proposed for review in the same manner as above, but are added to:
Specifications in this directory indicate the original author has either become unavailable, or has indicated that they are not going to implement the specification. The specifications found here are available as projects for people looking to get involved with Nova. If you are interested in claiming a spec, start by posting a review for the specification that moves it from this directory to the next active release. Please set yourself as the new primary assignee and maintain the original author in the other contributors list.
Design documents for releases prior to Juno¶
Prior to the Juno development cycle, this repository was not used for spec reviews. Reviews prior to Juno were completed entirely through Launchpad blueprints
Please note, Launchpad blueprints are still used for tracking the current status of blueprints. For more information, see https://wiki.openstack.org/wiki/Blueprints
Working with gerrit and specification unit tests¶
For more information about working with gerrit, see http://docs.openstack.org/infra/manual/developers.html#development-workflow
To validate that the specification is syntactically correct (i.e. get more confidence in the Jenkins result), please execute the following command:
tox, the documentation will be available for viewing in HTML
format in the
Specification review policies¶
There are a number of review policies which nova-specs-core will apply when reviewing proposed specifications. They are:
Proposed changes which are trivial (very small amounts of code) and don’t change any of our public APIs are sometimes not required to provide a specification. In these cases a Launchpad blueprint is considered sufficient. These proposals are approved during the Open Discussion portion of the weekly nova IRC meeting. If you think your proposed feature is trivial and meets these requirements, we recommend you bring it up for discussion there before writing a full specification.
Previously approved specifications¶
Specifications are only approved for a single release. If your specification was previously approved but not implemented (or not completely implemented), then you must seek re-approval for the specification. You can re-propose your specification by doing the following:
- Copy (not move) your specification to the right directory for the current release.
- Update the document to comply with the new template.
- If there are no functional changes to the specification (only template changes) then add the Previously-approved: <release> tag to your commit message.
- Send for review.
- nova-specs-core will merge specifications which meet these requirements with a single +2.
Specifications which depend on merging code in other OpenStack projects¶
For specifications that depend on code in other OpenStack projects merging we will not approve the nova specification until the code in that other project has merged. The best example of this is Cinder and Neutron drivers. To indicate your specification is in this state, please use the Depends-On git commit message tag. The correct format is Depends-On: <change id of other work>. nova-specs-core can approve the specification at any time, but it wont merge until the code we need to land in the other project has merged as well.
New libvirt image backends¶
There are some cases where an author might propose adding a new libvirt driver image storage backend which does not require code in other OpenStack projects. An example was the ceph image storage backend, if we treat that as separate from the ceph volume support code. Implementing a new image storage backend in the libvirt drive always requires a specification because of our historical concerns around adequate CI testing.