API reference guideline

The API reference should be updated when placement APIs are modified (microversion is bumped, etc.). This page describes the guideline for updating the API reference.

API reference

The guideline to write the API reference

The API reference consists of the following files.

  • API reference text: api-ref/source/*.inc

  • Parameter definition: api-ref/source/parameters.yaml

  • JSON request/response samples: api-ref/source/samples/*

Structure of inc file

Each REST API is described in the text file (*.inc). The structure of inc file is as follows:

  • Title

    • API Name

      • REST Method

        • URL

        • Description

        • Normal status code

        • Error status code

        • Request

          • Parameters

          • JSON request body example (if exists)

        • Response

          • Parameters

          • JSON response body example (if exists)

    • API Name (Next)

REST Method

The guideline for describing HTTP methods is described in this section. All supported methods by resource should be listed in the API reference.

The order of methods

Methods have to be sorted by each URI in the following order:

  1. GET

  2. POST

  3. PUT

  4. PATCH (unused by Nova)


And sorted from broadest to narrowest. So for /severs it would be:

  1. GET /servers

  2. POST /servers

  3. GET /servers/details

  4. GET /servers/{server_id}

  5. PUT /servers/{server_id}

  6. DELETE /servers/{server_id}

Method titles spelling and case

The spelling and the case of method names in the title have to match what is in the code. For instance, the title for the section on method “Get Rdp Console” should be “Get Rdp Console (os-getRDPConsole Action)” NOT “Get Rdp Console (Os-Getrdpconsole Action)”

Response codes

The normal response codes (20x) and error response codes have to be listed. The order of response codes should be in ascending order. The description of typical error response codes are as follows:

Error response codes

Response codes



















Parameters need to be defined by 2 subsections. The one is in the ‘Request’ subsection, the other is in the ‘Response’ subsection. The queries, request headers and attributes go in the ‘Request’ subsection and response headers and attributes go in the ‘Response’ subsection.

The order of parameters in each API

The request and response parameters have to be listed in the following order in each API in the text file.

  1. Header

  2. Path

  3. Query

  4. Body

    1. Top level object (i.e. server)

    2. Required fields

    3. Optional fields

    4. Parameters added in microversions (by the microversion they were added)

Parameter type

The parameters are defined in the parameter file (parameters.yaml). The type of parameters have to be one of followings:

  • array

    It is a list.

  • boolean

  • float

  • integer

  • none

    The value is always null in a response or should be null in a request.

  • object

    The value is dict.

  • string

    If the value can be specified by multiple types, specify one type in the file and mention the other types in the description.

Required or optional

In the parameter file, define the required field in each parameter.


The parameter must be specified in the request, or the parameter always appears in the response.


It is not always necessary to specify the parameter in the request, or the parameter does not appear in the response in some cases. e.g. A config option defines whether the parameter appears in the response or not. A parameter appears when administrators call but does not appear when non-admin users call.

If a parameter must be specified in the request or always appears in the response in the micoversion added or later, the parameter must be defined as required (true).

The order of parameters in the parameter file

The order of parameters in the parameter file has to be kept as follows:

  1. By in type

    1. Header

    2. Path

    3. Query

    4. Body

  2. Then alphabetical by name



The guideline for request/response JSON bodies should be added.



The guideline for the introductory text and the context for the resource in question should be added.