# Querying a Specified API Version

#### Function Description

This API is used to query the information of a specified version.

To support function extension, Nova APIs can be distinguished by version. There are two types of versions:

- Major version: Independent URL
- Microversion: Used by the HTTP request header X-OpenStack-Nova-API-Version. Since version 2.27, the new microversion header OpenStack-API-Version has been supported.

  If the OpenStack-API-Version request header is used, the version is in the format of "compute microversion".

  For example, if key is set to OpenStack-API-Version, set value to compute 2.27.

#### URI

GET /{api_version}

Table 1 describes the parameters in the URI.

Table 1 Parameter description
Parameter | Mandatory | Description
--- | --- | ---
api_version | Yes | Specifies an API version, such as V2.

#### Request

None

#### Response

The following table describes the response parameters.

Table 2 Response parameters
Parameter | Type | Description
--- | --- | ---
versions | Object | Specifies the versions. For details, see Table 3.

Table 3 versions field description
Parameter | Type | Description
--- | --- | ---
id | string | Specifies the version ID.
links | Object | Specifies the links to resources. For more information, see the OpenStack Documentation. For details, see Table 4.
media-types | Object | Specifies the media types. For details, see Table 5.

min_version

string

- Specifies the microversion. If the APIs of this version support microversions, set this parameter to the supported minimum microversion.
- If the microversion is not supported, leave this parameter blank.

status

string

Specifies the API version status. Possible values are as follows:

- CURRENT: This is the preferred API version.
- SUPPORTED: This is the old API version that is still supported.
- DEPRECATED: This is the deprecated API version that will be removed.

updated | string | The value of this parameter varies by API version. If the API version is 2.0, the value is 2011-01-21T11:33:21Z. If the API version is 2.1, the value is 2013-07-23T11:33:21Z.

version

string

- Specifies the microversion. If the APIs of this version support microversions, set this parameter to the supported maximum microversion.
- If the microversion is not supported, leave this parameter blank.

Table 4 links field description
Parameter | Type | Description
--- | --- | ---
href | string | Specifies the links of the corresponding resources.

rel

string

- self: A self link contains a versioned link to the resource. Use these links when the link is followed immediately.
- bookmark: A bookmark link provides a permanent link to a resource that is appropriate for long term storage.
- alternate: An alternate link can contain an alternate representation of the resource. For example, an OpenStack Compute image might have an alternate representation in the OpenStack Image service.

Table 5 media-types field description
Parameter | Type | Description
--- | --- | ---
base | string | Specifies the basic type.
type | string | Specifies the media type.

#### Example Request

    GET https://{endpoint}/v2

#### Example Response

    {
     "version": {
      "min_version": "",
      "media-types": [{
       "type": "application/vnd.openstack.compute+json;version=2",
       "base": "application/json"
      }],
      "links": [{
       "rel": "self",
       "href": "https://ecs.service.domain.com:443/v2/"
      },
      {
       "rel": "describedby",
       "href": "http://docs.openstack.org/",
       "type": "text/html"
      }],
      "id": "v2.0",
      "updated": "1999-02-20T11:33:21Z",
      "version": "",
      "status": "SUPPORTED"
     }
    }

#### Returned Values

See Returned Values for General Requests.

Parent topic: API Version Query