nova/api-guide/source/links_and_references.rst

Links and references

Often resources need to refer to other resources. For example, when creating a server, you must specify the image from which to build the server. You can specify the image by providing an ID or a URL to a remote image. When providing an ID, it is assumed that the resource exists in the current OpenStack deployment.

Example: ID image reference: JSON request

{
   "server":{
      "flavorRef":"http://openstack.example.com/openstack/flavors/1",
      "imageRef":"http://openstack.example.com/openstack/images/70a599e0-31e7-49b7-b260-868f441e862b",
      "metadata":{
         "My Server Name":"Apache1"
      },
      "name":"new-server-test",
      "personality":[
         {
            "contents":"ICAgICAgDQoiQSBjbG91ZCBkb2VzIG5vdCBrbm93IHdoeSBpdCBtb3ZlcyBpbiBqdXN0IHN1Y2ggYSBkaXJlY3Rpb24gYW5kIGF0IHN1Y2ggYSBzcGVlZC4uLkl0IGZlZWxzIGFuIGltcHVsc2lvbi4uLnRoaXMgaXMgdGhlIHBsYWNlIHRvIGdvIG5vdy4gQnV0IHRoZSBza3kga25vd3MgdGhlIHJlYXNvbnMgYW5kIHRoZSBwYXR0ZXJucyBiZWhpbmQgYWxsIGNsb3VkcywgYW5kIHlvdSB3aWxsIGtub3csIHRvbywgd2hlbiB5b3UgbGlmdCB5b3Vyc2VsZiBoaWdoIGVub3VnaCB0byBzZWUgYmV5b25kIGhvcml6b25zLiINCg0KLVJpY2hhcmQgQmFjaA==",
            "path":"/etc/banner.txt"
         }
      ]
   }
}

Example: Full image reference: JSON request

{
    "server": {
        "name": "server-test-1",
        "imageRef": "b5660a6e-4b46-4be3-9707-6b47221b454f",
        "flavorRef": "2",
        "max_count": 1,
        "min_count": 1,
        "networks": [
            {
                "uuid": "d32019d3-bc6e-4319-9c1d-6722fc136a22"
            }
        ],
        "security_groups": [
            {
                "name": "default"
            },
            {
                "name": "another-secgroup-name"
            }
        ]
    }
}

For convenience, resources contain links to themselves. This allows a client to easily obtain rather than construct resource URIs. The following types of link relations are associated with resources:

• A self link contains a versioned link to the resource. Use these links when the link is followed immediately.
• A bookmark link provides a permanent link to a resource that is appropriate for long term storage.
• 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.

Note

The type attribute provides a hint as to the type of representation to expect when following the link.

Example: Server with self links: JSON

{
   "server":{
      "id":"52415800-8b69-11e0-9b19-734fcece0043",
      "name":"my-server",
      "links":[
         {
            "rel":"self",
            "href":"http://servers.api.openstack.org/v2.1/servers/52415800-8b69-11e0-9b19-734fcece0043"
         },
         {
            "rel":"bookmark",
            "href":"http://servers.api.openstack.org/servers/52415800-8b69-11e0-9b19-734fcece0043"
         }
      ]
   }
}

Example: Server with alternate link: JSON

{
    "image" : {
        "id" : "52415800-8b69-11e0-9b19-734f5736d2a2",
        "name" : "My Server Backup",
        "links": [
            {
                "rel" : "self",
                "href" : "http://servers.api.openstack.org/v2.1/images/52415800-8b69-11e0-9b19-734f5736d2a2"
            },
            {
                "rel" : "bookmark",
                "href" : "http://servers.api.openstack.org/images/52415800-8b69-11e0-9b19-734f5736d2a2"
            },
            {
                "rel"  : "alternate",
                "type" : "application/vnd.openstack.image",
                "href" : "http://glance.api.openstack.org/1234/images/52415800-8b69-11e0-9b19-734f5736d2a2"
            }
        ]
    }
}