Usage¶

os-api-ref is designed to be used inside of a sphinx tree that is devoted solely to the documentation of the API.

Modify your source/conf.py file to include os_api_ref in the list of sphinx extensions. This extension assumes you are also using openstackdocstheme for some of the styling, and may not fully work if you are not.

# Add any Sphinx extension module names here, as strings. They can be
# extensions coming with Sphinx (named 'sphinx.ext.*') or your custom ones.

extensions = [
    'os_api_ref',
]

Stanzas¶

rest_method¶

The rest_method stanza is a way to declare that a section is about a particular REST method. It takes the form of:

.. rest_method:: <METHODNAME> <url>

METHODNAME should be one of the commonly used REST methods or HTTP verbs. This stanza should be the first element in a section that has some descriptive title about the method. An example from the Nova documentation is:

List Servers
============

.. rest_method:: GET /v2.1/{tenant_id}/servers

Lists IDs, names, and links for all servers.


Servers contain a status attribute that indicates the current server
state. You can filter on the server status when you complete a list
servers request. The server status is returned in the response
body. The possible server status values are:

...

This is going to do a slightly unexpected transform where the rest_method is pivoted up and into the section title to produce an HTML line of the form: <METHOD> <URL> <SECTIONTITLE> <SHOW/HIDE BUTTON>.

The entire contents of the List Servers section will then be hidden by default, with a button to open it on demand.

rest_parameters¶

The rest_parameters stanza is a solution to the problem of tables in rst.

A REST API that uses JSON has a large number of structured parameters that include type, location (i.e. is this in the query, the header, the path, the body), whether or not this parameter is required, as well as the desire to provide a long description about each parameter. And, assuming some consistent modeling, that parameter will show up in multiple calls. A server_id used in the path is always going to have the same meaning.

It is natural to want to display this data in a tabular way to show all these dimensions. However, tables in rst are quite cumbersome, and repeating the same data over and over again is error prone.

The rest_parameters stanza solves this by having the inline markup be a yaml list of name: value pairs. name is the name of the parameter. value is the key to lookup the rest of the details for this parameter in a parameters file. In each method, there should be one rest_parameters stanza for the request, and another rest_parameters stanza for the response.

.. rest_parameters:: parameters.yaml

   - tenant_id: tenant_id
   - changes-since: changes-since
   - image: image_query
   - flavor: flavor_query
   - name: server_name_query
   - status: server_status_query
   - host: host_query
   - limit: limit
   - marker: marker

And corresponding entries in parameters.yaml:

tenant_id:
  description: |
    The UUID of the tenant in a multi-tenancy cloud.
  in: path
  required: true
  type: string
...
changes-since:
  description: |
    Filters the response by a date and time when the image last changed status.
    Use this query parameter to check for changes since a previous request rather
    than re-downloading and re-parsing the full status at each polling interval.
    If data has changed, the call returns only the items changed since the ``changes-since``
    time. If data has not changed since the ``changes-since`` time, the call returns an
    empty list.\nTo enable you to keep track of changes, this filter also displays images
    that were deleted if the ``changes-since`` value specifies a date in the last 30 days.
    Items deleted more than 30 days ago might be returned, but it is not guaranteed.
    The date and time stamp format is `ISO 8601 <https://en.wikipedia.org/wiki/ISO_8601>`_:

    ::

       CCYY-MM-DDThh:mm:ss±hh:mm

    The ``±hh:mm`` value, if included, returns the time zone as an offset from UTC.
    For example, ``2015-08-27T09:49:58-05:00``.
    If you omit the time zone, the UTC time zone is assumed.
  in: query
  required: false
  type: string
server_status_query:
  description: |
    Filters the response by a server status, as a string. For example, ``ACTIVE``.
  in: query
  required: false
  type: string

Every rest_parameters stanza specifies the lookup file it will use. This gives you the freedom to decide how you would like to split up your parameters, ranging from a single global file, to a dedicated file for every stanza, or anywhere in between.

parameters file format¶

The parameters file is inspired by the OpenAPI (aka: Swagger) specification. The OpenAPI specification provides a property object which categorizes the parameters by type and describes how the parameter is used. The following fields exist for every entry:

in: where this parameter exists. One of header, path, query, body.
description: a free form description of the parameter. This can be multiline (if using the | or > tags in yaml), and supports rst format syntax.
required: whether this parameter is required or not. If required: false the parameter name will be rendered with an (Optional) keyword next to it
type: the javascript/json type of the field. one of boolean, int, float, string, uuid, array, object.
min_version: the microversion that this parameter was introduced at. Will render a new in $version stanza in the html output.
max_version: the last version that includes this parameter. Will render a Available until $version stanza in the html output.

rest_status_code¶

The rest_status_code stanza is how you can show what HTTP status codes your API uses and what they indicate.

.. rest_status_code:: <success|error> <location of http-status.yaml file>

This stanza should be the first element after the narrative section of the method description.

An example from the Designate documentation is:

Create Zone
===========

.. rest_method::  POST /v2/zones

Create a zone

Response codes
--------------

.. rest_status_code:: success status.yaml

   - 200
   - 100
   - 201


.. rest_status_code:: error status.yaml

   - 405
   - 403
   - 401
   - 400
   - 500
   - 409: duplicate_zone

And corresponding entries in http-status.yaml:

100:
  default: |
    An unusual code for an API
200:
  default: |
    Request was successful.
201:
  default: >
    Request has been fulfilled and new resource created. The ``Location`` header
    has the URL to the new item.
400:
  default: |
    Some content in the request was invalid
  zone_data_error: |
    Some of the data for the zone in the request is unavailable to the service.
401:
  default: |
    User must authenticate before making a request.
403:
  default: |
     Policy does not allow current user to do this operation.
405:
  default: |
    Method is not valid for this endpoint and resource.
409:
 default: |
    This resource has an action in progress that would conflict with this request.
 duplicate_zone: |
    There is already a zone with this name.
500:
  default: |
    Something went wrong with the service which prevents it from fulfilling the request.

This RST example creates two HTML tables of response codes, one for success and one for errors.

status file format¶

This is a simple yaml file, with a single object of status codes and the reasons that each would be used.

Each status code must have a default entry in the status yaml file. The default entry is used in the rest_status_code stanza when a code is listed with no value or lookup key.

There may be situations where the reason for a code may be different across endpoints, or a different message may be appropriate.

In this case, adding a entry at the same level as the default and referencing that in the stanza like so:

- 409: duplicate_zone

This will override the default message with the newly defined one.

You can get a copy of a starter status file from the os-api-ref repository, by downloading http-status.yaml.

rest_expand_all¶

The rest_expand_all stanza is used to place a control in the document that will be a global Show / Hide for all sections. There are times when this is extremely nice to have.

Including Sample Files¶

To refer to a sample file in a rst file, use the rst directive, literalinclude. Typically, the content sent or received is of type JSON, so the language role is set to javascript. The example immediately follows the parameter listing in the rst file. An example of an included Nova response sample file:

.. literalinclude:: ../../doc/api_samples/os-evacuate/server-evacuate-resp.json
   :language: javascript

Runtime Warnings¶

The extension tries to help when it can by pointing out that something isn’t matching up correctly. The following warnings are generated when issues are found:

parameters file is not found
parameters file is not valid yaml, i.e. missing colon after the name
a lookup value in the rst file is not found in the parameters file
the parameters file is not sorted as outlined in the rules below

The sorting rules for parameters file is that first elements should be sorted by in, going from earliest to latest processed.

header
path
query
body

After that, the parameters should be sorted by name, lower case alpha numerically.

The sort enforcement is because in large parameters files it helps prevent unintended duplicates.

Usage