API Discovery with JSON Home

What is JSON Home?

JSON Home describes a method of API discovery for non-browser HTTP clients. The draft is still in review, but keystone supplies an implementation accessible to end-users. The result of calling keystone’s JSON Home API is a JSON document that informs the user about API endpoints, where to find them, and even information about the API’s status (e.g. experimental, supported, deprecated). More information keystone’s implementation of JSON Home can be found in the specification.

Requesting JSON Home Documents

Requesting keystone’s JSON Home document is easy. The API does not require a token, but future implementations might expand in it’s protection with token validation and enforcement. To get a JSON Home document, just query a keystone endpoint with application/json-home specified in the Accept header:

curl -X GET -H "Accept: application/json-home" http://example.com/identity/

The result will be a JSON document containing a list of resources:

    "resources": [
        "https://docs.openstack.org/api/openstack-identity/3/ext/OS-TRUST/1.0/rel/trusts": {
            "href": "/v3/OS-TRUST/trusts"
        "https://docs.openstack.org/api/openstack-identity/3/ext/s3tokens/1.0/rel/s3tokens": {
            "href": "/v3/s3tokens"
        "https://docs.openstack.org/api/openstack-identity/3/rel/application_credential": {
            "href-template": "/v3/users/{user_id}/application_credentials/{application_credential_id}",
            "href-vars": {
                "application_credential_id": "https://docs.openstack.org/api/openstack-identity/3/param/application_credential_id",
                "user_id": "https://docs.openstack.org/api/openstack-identity/3/param/user_id"
        "https://docs.openstack.org/api/openstack-identity/3/rel/auth_catalog": {
            "href": "/v3/auth/catalog"
        "https://docs.openstack.org/api/openstack-identity/3/rel/auth_domains": {
            "href": "/v3/auth/domains"
        "https://docs.openstack.org/api/openstack-identity/3/rel/auth_projects": {
            "href": "/v3/auth/projects"
        "https://docs.openstack.org/api/openstack-identity/3/rel/auth_system": {
            "href": "/v3/auth/system"

The list of resources can then be parsed based on the relationship key for a dictionary of data about that endpoint. This includes a path where users can find interact with the endpoint for that specific resources. API status information will also be present.