keystone/api-ref/source/v3/samples/admin/endpoint-create-request.json

{
    "endpoint": {
        "interface": "public",
        "region_id": "RegionOne",
        "url": "http://example.com/identity/v3/endpoints/828384",
        "service_id": "9242e05f0c23467bbd1cf1f7a6e5e596"
    }
}