Include the URL of your launchpad blueprint:
Introduction paragraph – why are we doing anything? A single paragraph of prose that operators can understand. The title and this first paragraph should be used as the subject line and body of the commit message respectively.
Some notes about the watcher-spec and blueprint process:
Not all blueprints need a spec. For more information see http://docs.openstack.org/developer/watcher/devref/mitaka.blueprints.html#when-is-a-blueprint-needed
The aim of this document is first to define the problem we need to solve, and second agree the overall approach to solve that problem.
This is not intended to be extensive documentation for a new feature. For example, there is no need to specify the exact configuration changes,
nor the exact details of any DB model changes. But you should still define that such changes are required, and be clear on how that will affect upgrades.
You should aim to get your spec approved before writing your code. While you are free to write prototypes and code before getting your spec approved, its possible that the outcome of the spec review process leads you towards a fundamentally different solution than you first envisaged.
But, API changes are held to a much higher level of scrutiny. As soon as an API change merges, we must assume it could be in production somewhere, and as such, we then need to support that API change forever. To avoid getting that wrong, we do want lots of details about API changes upfront.
Some notes about using this template:
Your spec should be in ReSTructured text, like this template.
Please wrap text at 79 columns.
The filename in the git repository should match the launchpad URL, for example a URL of: https://blueprints.launchpad.net/watcher/+spec/awesome-thing should be named awesome-thing.rst
Please do not delete any of the sections in this template. If you have nothing to say for a whole section, just write: None
For help with syntax, see http://sphinx-doc.org/rest.html
To test out your formatting, build the docs using tox and see the generated HTML file in doc/build/html/specs/<path_of_your_file>
If you would like to provide a diagram with your spec, ascii diagrams are required. http://asciiflow.com/ is a very nice tool to assist with making ascii diagrams. The reason for this is that the tool used to review specs is based purely on plain text. Plain text will allow review to proceed without having to look at additional files which can not be viewed in gerrit. It will also allow inline feedback on the diagram itself.
If your specification proposes any changes to the Watcher REST API such as changing parameters which can be returned or accepted, or even the semantics of what happens when a client calls into the API, then you should add the APIImpact flag to the commit message. Specifications with the APIImpact flag can be found with the following query:
A detailed description of the problem. What problem is this blueprint addressing?
What use cases does this address? What impact on actors does this change have? Ensure you are clear about the actors in each use case: Developer, End User, Deployer etc.
Here is where you cover the change you propose to make in detail. How do you propose to solve this problem?
If this is one part of a larger effort make it clear where this piece ends. In other words, what’s the scope of this effort?
At this point, if you would like to just get feedback on if the problem and proposed change fit in Watcher, you can stop here and post this for review to get preliminary feedback. If so please say: Posting to get preliminary feedback on the scope of this spec.
What other ways could we do this thing? Why aren’t we using those? This doesn’t have to be a full literature review, but it should demonstrate that thought has been put into why the proposed solution is an appropriate one.
Changes which require modifications to the data model often have a wider impact on the system. The community often has strong opinions on how the data model should be evolved, from both a functional and performance perspective. It is therefore important to capture and gain agreement as early as possible on any proposed changes to the data model.
Questions which need to be addressed by this section include:
Each API method which is either added or changed should have the following
Note that the schema should be defined as restrictively as possible. Parameters which are required should be marked as such and only under exceptional circumstances should additional parameters which are not defined in the schema be permitted (e.g., additionalProperties should be False).
Reuse of existing predefined parameter types such as regexps for passwords and user defined names is highly encouraged.
Describe any potential security impact on the system. Some of the items to consider include:
For more detailed guidance, please see the OpenStack Security Guidelines as a reference (https://wiki.openstack.org/wiki/Security/Guidelines). These guidelines are a work in progress and are designed to help you identify security best practices. For further information, feel free to reach out to the OpenStack Security Group at firstname.lastname@example.org.
Please specify any changes to notifications. Be that an extra notification, changes to an existing notification, or removing a notification.
Aside from the API, are there other ways a user will interact with this feature?
Describe any potential performance impact on the system, for example how often will new code be called, and is there a major change to the calling pattern of existing code.
Examples of things to consider here include:
Discuss things that will affect how you deploy and configure OpenStack that have not already been mentioned, such as:
Discuss things that will affect other developers working on OpenStack.
Who is leading the writing of the code? Or is this a blueprint where you’re throwing it out there to see who picks it up?
If more than one person is working on the implementation, please designate the primary author and contact.
Work items or tasks – break the feature up into the things that need to be done to implement it. Those parts might end up being done by different people, but we’re mostly trying to understand the timeline for implementation.
Please discuss the important scenarios needed to test here, as well as specific edge cases we should be ensuring work correctly. For each scenario please specify if this requires specialized hardware, a full openstack environment, or can be simulated inside the Watcher tree.
Please discuss how the change will be tested. We especially want to know what tempest tests will be added. It is assumed that unit test coverage will be added so that doesn’t need to be mentioned explicitly, but discussion of why you think unit tests are sufficient and we don’t need to add more tempest tests would need to be included.
Is this untestable in gate given current limitations (specific hardware / software configurations available)? If so, are there mitigation plans (3rd party testing, gate enhancements, etc).
What is the impact on the docs team of this change? Some changes might require donating resources to the docs team to have the documentation updated. Don’t repeat details discussed above, but please reference them here.
Please add any useful references here. You are not required to have any reference. Moreover, this specification should still make sense when your references are unavailable. Examples of what you could include are:
Optional section for liberty intended to be used each time the spec is updated to describe new design, API or any database schema updated. Useful to let reader understand what’s happened along the time.