API functions

The Danube Cloud API is built on top of modern technologies to provide fast and secure operations inside a virtualization based datacenter. Some of these technologies communicate together using asynchronous messages and others pass information using classic synchronous communication protocols. There are two types of functions available in the API depending on the kind of technologies they use to achieve the goal (synchronous and asynchronous).

Synchronous API functions

Most of the API functions are synchronous. The response from these functions is always a JSON object or array. In the case of a success response, the HTTP status code will be 200 or 201 (new object was created). The failure status codes (>=400) are different and well documented for each API function. If a function call leads to a database change, the results are logged into the task log (retrievable via GET /task/log). The task ID provided in the success response is only used as a reference to the task log entry.

Asynchronous API functions

Some of the API functions can be asynchronous, which means that they can create tasks, and the result of the operation is not available immediately after the function ends. The task result can be retrieved later by using GET /task/(task_id)/status API call, or it can be delivered to a URL via a user-defined HTTP callback. The es command line client always tries to wait for the task result with a timeout set to 3600 seconds.

In the case of parameter processing errors or failed condition checks, the function behaves like a classical synchronous API function giving a direct response with a failure status code (>=400). In some cases, the function can also create a synchronous success response with a 200 status code. When a task is created the function returns a 201 status code and the response contains a task_id and state attribute with the value set to PENDING or STARTED. The asynchronous API function always creates two task log entries with the same task ID (one when a task is created and another one when the task is finished).

User Callbacks

All asynchronous functions support user-defined callbacks where the result of a PENDING or STARTED task is sent once it has finished. Function parameters required to create a callback are cb_url and cb_method. The task result is sent as a JSON-encoded string in the body of an HTTP request to the URL provided in the cb_url parameter. Valid choices for the cb_method parameter are GET/POST/PUT/DELETE. The default value is POST.

es example:

es set /vm/example.cust.erigones.com/status/start -cb_method POST -cb_url http://remote.server.com/sample/callback/url/
    "url": "https://my.erigones.com/api/vm/example.cust.erigones.com/status/start/",
    "status": 200,
    "method": "PUT",
    "text": {
        "status": "SUCCESS",
        "result": {
            "message": "Successfully started VM example.cust.erigones.com",
            "returncode": 0
        "task_id": "0-a2327793-2600-423d-9f07"

With each callback, a random_token and security_token attribute is included in the JSON body of the HTTP request, so it is possible to check if callback request has not been faked. The random_token is randomly generated for every callback request. The security_token is a md5 hash of the random_token joined with user’s callback_key. To verify the request just join the random_token with your callback_key and create a md5 hash. Your md5 hash must be identical to the security_token provided in the request.

Callback verification example:

$json_response = json_decode($HTTP_RAW_POST_DATA, TRUE);

if (md5($json_response['random_token'] . $user->callback_key) == $json_response['security_token']) {
        print('Comparison of tokens SUCCEEDED! We can trust request... ');
} else {
        print('Comparison of tokens FAILED! Something dodgy is going on... ');

HTTP headers

Every API response contains following HTTP headers:

Header name Example value Description
es_version 2.0.3 Danube Cloud version
es_username admin User who sent the API request
es_dc main Currently active virtual datacenter

Common API parameters

Many API functions accept the same GET/POST/PUT/DELETE parameters:

  • order_by - Comma-separated list of fields used for sorting a list of items. A + or - sign before the field name indicates sorting in descending order.