6.5. RackHD API

Our REST based API is the abstraction layer for the low-level management tasks that are performed on hardware devices, and information about those devices. For example, when a compute server is “discovered” (see System Architecture for more details on this process), the information about that server is expressed as nodes and catalogs in the RackHD API. When you want to re-image that compute node, the RackHD API is used to activate a workflow containing the tasks that are appropriate to doing that function.

The RackHD API can be used to manage nodes, catalogs, workflows, tasks, templates, pollers, and other entities. For the complete list of functions, generate the RackHD API documentation as described below or download the latest from https://bintray.com/rackhd/docs/apidoc#files.

List All Nodes

curl http://<server>:8080/api/current/nodes | python -mjson.tool

Set the Active Workflow

curl http://<server>:8080/api/current/nodes/<identifier>/workflows/active | python -mjson.tool

6.5.1. Starting and Stopping the API Server

The API server runs by default. Use the following commands to stop or start the API server.

Action Command
Stop API server sudo service on-http stop
Start API server sudo service on-http start

6.5.2. Generating API Documentation

You can generate an HTML version of the API documentation by cloning the on-http repository and running the following command.

$ git clone https://github.com/RackHD/on-http
$ cd on-http
$ npm install
$ npm run apidoc

The default and example quick start build that we describe in RackHD: local Vagrant based setup has the API docs rendered and embedded within that instance for easy use, available at http://[IP ADDRESS OF VM]:8080/docs/ for the 1.1 API documentation, and http://[IP ADDRESS OF VM]:8080/swagger-ui/ for the current (2.0) and Redfish API documentation.

6.5.3. RackHD Client Libraries

The 1.1 API for RackHD includes annotations in code that are used to generate API documentation (the npm run apidoc command above) that is hosted directly within RackHD.

A similiar process generates a swagger API definition file that can be used to create client libraries with swagger. To create this file locally, you can check out the on-http library and run the commands:

npm install
npm run apidoc-swagger

The resulting file will be build/apidoc-swagger/swagger.json. You can use this file with swagger tools to generate client libraries in any of the languages that swagger supports. RackHD travis build for on-http includes using codegen from swagger tools to generate a python library, available in a debian package, that we use with integration testing.

You can also use the swagger generator online tool to generate a client zip bundle for a variety of languages, including python, Java, javascript, ruby, scala, php, and more.

6.5.4. Examples using the python client library

Getting a list of nodes:

from on_http import NodesApi, ApiClient, Configuration

config = Configuration()
config.debug = True
config.verify_ssl = False

client = ApiClient(host='http://localhost:9090',header_name='Content-Type',header_value='application/json')
nodes = NodesApi(api_client=client)
nodes.api1_1_nodes_get()
print client.last_response.data

2.0 API - Getting a list of nodes

from on_http import NodesApi, ApiClient, Configuration

    config = Configuration()
    config.debug = True
    config.verify_ssl = False

    client = ApiClient(host='http://localhost:9090',header_name='Content-Type',header_value='application/json')
    nodes = NodesApi(api_client=client)
    nodes.api2_0_nodes_get()
    print client.last_response.data

Or the same asynchronously (with a callback):

def cb_func(resp):
print 'GET /nodes callback!', resp

thread = nodes.api1_1_nodes_get(callback=cb_func)

2.0 API - Or the same asynchronously (with a callback):

def cb_func(resp):
print 'GET /nodes callback!', resp

thread = nodes.api2_0_nodes_get(callback=cb_func)

6.5.5. Using Pagination

The RackHD 2.0 /nodes, /pollers, and /workflows APIs support pagination using $skip and $top query parameters.

Parameter Description
$skip An integer indicating the number of items that should be skipped starting with the first item in the collection.
$top An integeter indicating the number of items that should be included in the response.

These parameters can be used individually or combined to display any subset of consecutive resources in the collection.

Here is an example request using $skip and $top to get get the second page of nodes with four items per page.

curl http://localhost:8080/api/current/nodes?$skip=4&$top=4

RackHD will add a link header to assist in traversing a large collection. Links will be added if either $skip or $top is used and the size of the collection is greater than the number of resources displayed (i.e. the collection cannot fit on one page). If applicable, links to first, last, next, and previous pages will be included in the header. The next and previous links will be ommitted for the last and first pages respectively.

Here is an example link header from a collection containing 1000 nodes.

</api/current/nodes?$skip=0&$top=4>; rel="first",
</api/current/nodes?$skip=1004&$top=4>; rel="last",
</api/current/nodes?$skip=0&$top=4>; rel="prev",
</api/current/nodes?$skip=8&$top=4>; rel="next"