2 This work is licensed under a Creative Commons Attribution 3.0 Unported
5 http://creativecommons.org/licenses/by/3.0/legalcode
7 ==========================================
8 Example Spec - The title of your blueprint
9 ==========================================
11 Include the URL of your launchpad blueprint:
13 https://blueprints.launchpad.net/nova/+spec/example
15 Introduction paragraph -- why are we doing anything? A single paragraph of
16 prose that operators can understand. The title and this first paragraph
17 should be used as the subject line and body of the commit message
20 Some notes about the nova-spec and blueprint process:
22 * Not all blueprints need a spec. For more information see
23 http://docs.openstack.org/developer/nova/devref/kilo.blueprints.html#when-is-a-blueprint-needed
25 * The aim of this document is first to define the problem we need to solve,
26 and second agree the overall approach to solve that problem.
28 * This is not intended to be extensive documentation for a new feature.
29 For example, there is no need to specify the exact configuration changes,
31 nor the exact details of any DB model changes. But you should still define
32 that such changes are required, and be clear on how that will affect
35 * You should aim to get your spec approved before writing your code.
36 While you are free to write prototypes and code before getting your spec
37 approved, its possible that the outcome of the spec review process leads
38 you towards a fundamentally different solution than you first envisaged.
40 * But, API changes are held to a much higher level of scrutiny.
41 As soon as an API change merges, we must assume it could be in production
42 somewhere, and as such, we then need to support that API change forever.
43 To avoid getting that wrong, we do want lots of details about API changes
46 Some notes about using this template:
48 * Your spec should be in ReSTructured text, like this template.
50 * Please wrap text at 79 columns.
52 * The filename in the git repository should match the launchpad URL, for
53 example a URL of: https://blueprints.launchpad.net/nova/+spec/awesome-thing
54 should be named awesome-thing.rst
56 * Please do not delete any of the sections in this template. If you have
57 nothing to say for a whole section, just write: None
59 * For help with syntax, see http://sphinx-doc.org/rest.html
61 * To test out your formatting, build the docs using tox and see the generated
62 HTML file in doc/build/html/specs/<path_of_your_file>
64 * If you would like to provide a diagram with your spec, ascii diagrams are
65 required. http://asciiflow.com/ is a very nice tool to assist with making
66 ascii diagrams. The reason for this is that the tool used to review specs is
67 based purely on plain text. Plain text will allow review to proceed without
68 having to look at additional files which can not be viewed in gerrit. It
69 will also allow inline feedback on the diagram itself.
71 * If your specification proposes any changes to the Nova REST API such
72 as changing parameters which can be returned or accepted, or even
73 the semantics of what happens when a client calls into the API, then
74 you should add the APIImpact flag to the commit message. Specifications with
75 the APIImpact flag can be found with the following query:
77 https://review.openstack.org/#/q/status:open+project:openstack/nova-specs+message:apiimpact,n,z
83 A detailed description of the problem. What problem is this blueprint
89 What use cases does this address? What impact on actors does this change have?
90 Ensure you are clear about the actors in each use case: Developer, End User,
96 Here is where you cover the change you propose to make in detail. How do you
97 propose to solve this problem?
99 If this is one part of a larger effort make it clear where this piece ends. In
100 other words, what's the scope of this effort?
102 At this point, if you would like to just get feedback on if the problem and
103 proposed change fit in nova, you can stop here and post this for review to get
104 preliminary feedback. If so please say:
105 Posting to get preliminary feedback on the scope of this spec.
110 What other ways could we do this thing? Why aren't we using those? This doesn't
111 have to be a full literature review, but it should demonstrate that thought has
112 been put into why the proposed solution is an appropriate one.
117 Changes which require modifications to the data model often have a wider impact
118 on the system. The community often has strong opinions on how the data model
119 should be evolved, from both a functional and performance perspective. It is
120 therefore important to capture and gain agreement as early as possible on any
121 proposed changes to the data model.
123 Questions which need to be addressed by this section include:
125 * What new data objects and/or database schema changes is this going to
128 * What database migrations will accompany this change.
130 * How will the initial set of new data objects be generated, for example if you
131 need to take into account existing instances, or modify other existing data
132 describe how that will work.
137 Each API method which is either added or changed should have the following
139 * Specification for the method
141 * A description of what the method does suitable for use in
144 * Method type (POST/PUT/GET/DELETE)
146 * Normal http response code(s)
148 * Expected error http response code(s)
150 * A description for each possible error code should be included
151 describing semantic errors which can cause it such as
152 inconsistent parameters supplied to the method, or when an
153 instance is not in an appropriate state for the request to
154 succeed. Errors caused by syntactic problems covered by the JSON
155 schema definition do not need to be included.
157 * URL for the resource
159 * URL should not include underscores, and use hyphens instead.
161 * Parameters which can be passed via the url
163 * JSON schema definition for the request body data if allowed
165 * Field names should use snake_case style, not CamelCase or MixedCase
168 * JSON schema definition for the response body data if any
170 * Field names should use snake_case style, not CamelCase or MixedCase
173 * Example use case including typical API samples for both data supplied
174 by the caller and the response
176 * Discuss any policy changes, and discuss what things a deployer needs to
177 think about when defining their policy.
179 Example JSON schema definitions can be found in the Nova tree
180 http://git.openstack.org/cgit/openstack/nova/tree/nova/api/openstack/compute/schemas
182 Note that the schema should be defined as restrictively as
183 possible. Parameters which are required should be marked as such and
184 only under exceptional circumstances should additional parameters
185 which are not defined in the schema be permitted (eg
186 additionaProperties should be False).
188 Reuse of existing predefined parameter types such as regexps for
189 passwords and user defined names is highly encouraged.
194 Describe any potential security impact on the system. Some of the items to
197 * Does this change touch sensitive data such as tokens, keys, or user data?
199 * Does this change alter the API in a way that may impact security, such as
200 a new way to access sensitive information or a new way to login?
202 * Does this change involve cryptography or hashing?
204 * Does this change require the use of sudo or any elevated privileges?
206 * Does this change involve using or parsing user-provided data? This could
207 be directly at the API level or indirectly such as changes to a cache layer.
209 * Can this change enable a resource exhaustion attack, such as allowing a
210 single API interaction to consume significant server resources? Some examples
211 of this include launching subprocesses for each connection, or entity
212 expansion attacks in XML.
214 For more detailed guidance, please see the OpenStack Security Guidelines as
215 a reference (https://wiki.openstack.org/wiki/Security/Guidelines). These
216 guidelines are a work in progress and are designed to help you identify
217 security best practices. For further information, feel free to reach out
218 to the OpenStack Security Group at openstack-security@lists.openstack.org.
223 Please specify any changes to notifications. Be that an extra notification,
224 changes to an existing notification, or removing a notification.
226 Other end user impact
227 ---------------------
229 Aside from the API, are there other ways a user will interact with this
232 * Does this change have an impact on python-novaclient? What does the user
233 interface there look like?
238 Describe any potential performance impact on the system, for example
239 how often will new code be called, and is there a major change to the calling
240 pattern of existing code.
242 Examples of things to consider here include:
244 * A periodic task might look like a small addition but if it calls conductor or
245 another service the load is multiplied by the number of nodes in the system.
247 * Scheduler filters get called once per host for every instance being created,
248 so any latency they introduce is linear with the size of the system.
250 * A small change in a utility function or a commonly used decorator can have a
251 large impacts on performance.
253 * Calls which result in a database queries (whether direct or via conductor)
254 can have a profound impact on performance when called in critical sections of
257 * Will the change include any locking, and if so what considerations are there
260 Other deployer impact
261 ---------------------
263 Discuss things that will affect how you deploy and configure OpenStack
264 that have not already been mentioned, such as:
266 * What config options are being added? Should they be more generic than
267 proposed (for example a flag that other hypervisor drivers might want to
268 implement as well)? Are the default values ones which will work well in
271 * Is this a change that takes immediate effect after its merged, or is it
272 something that has to be explicitly enabled?
274 * If this change is a new binary, how would it be deployed?
276 * Please state anything that those doing continuous deployment, or those
277 upgrading from the previous release, need to be aware of. Also describe
278 any plans to deprecate configuration values or features. For example, if we
279 change the directory name that instances are stored in, how do we handle
280 instance directories created before the change landed? Do we move them? Do
281 we have a special case in the code? Do we assume that the operator will
282 recreate all the instances in their cloud?
287 Discuss things that will affect other developers working on OpenStack,
290 * If the blueprint proposes a change to the driver API, discussion of how
291 other hypervisors would implement the feature is required.
300 Who is leading the writing of the code? Or is this a blueprint where you're
301 throwing it out there to see who picks it up?
303 If more than one person is working on the implementation, please designate the
304 primary author and contact.
307 <launchpad-id or None>
310 <launchpad-id or None>
315 Work items or tasks -- break the feature up into the things that need to be
316 done to implement it. Those parts might end up being done by different people,
317 but we're mostly trying to understand the timeline for implementation.
323 * Include specific references to specs and/or blueprints in nova, or in other
324 projects, that this one either depends on or is related to.
326 * If this requires functionality of another project that is not currently used
327 by Nova (such as the glance v2 API when we previously only required v1),
330 * Does this feature require any new library dependencies or code otherwise not
331 included in OpenStack? Or does it depend on a specific version of library?
337 Please discuss the important scenarios needed to test here, as well as
338 specific edge cases we should be ensuring work correctly. For each
339 scenario please specify if this requires specialized hardware, a full
340 openstack environment, or can be simulated inside the Nova tree.
342 Please discuss how the change will be tested. We especially want to know what
343 tempest tests will be added. It is assumed that unit test coverage will be
344 added so that doesn't need to be mentioned explicitly, but discussion of why
345 you think unit tests are sufficient and we don't need to add more tempest
346 tests would need to be included.
348 Is this untestable in gate given current limitations (specific hardware /
349 software configurations available)? If so, are there mitigation plans (3rd
350 party testing, gate enhancements, etc).
356 Which audiences are affected most by this change, and which documentation
357 titles on docs.openstack.org should be updated because of this change? Don't
358 repeat details discussed above, but reference them here in the context of
359 documentation for multiple audiences. For example, the Operations Guide targets
360 cloud operators, and the End User Guide would need to be updated if the change
361 offers a new feature available through the CLI or dashboard. If a config option
362 changes or is deprecated, note here that the documentation needs to be updated
363 to reflect this specification's change.
368 Please add any useful references here. You are not required to have any
369 reference. Moreover, this specification should still make sense when your
370 references are unavailable. Examples of what you could include are:
372 * Links to mailing list or IRC discussions
374 * Links to notes from a summit session
376 * Links to relevant research, if appropriate
378 * Related specifications as appropriate (e.g. if it's an EC2 thing, link the
381 * Anything else you feel it is worthwhile to refer to
387 Optional section for Mitaka intended to be used each time the spec
388 is updated to describe new design, API or any database schema
389 updated. Useful to let reader understand what's happened along the
392 .. list-table:: Revisions