Send a request to the API service (dlbv3)

This section shows how to send a request to the Dedicated Load Balancer API by using cURL.

For API development, testing, and workflow management in a graphical environment, try interacting with the API by using an application such as Postman or RESTClient for Firefox.

How to use cURL

cURL is a command-line tool that you can use to interact with REST interfaces. cURL lets you transmit and receive HTTP requests and responses from the command line or a shell script, which enables you to work with the API directly. cURL is available for Linux® distributions, Mac OS® X, and Microsoft Windows®. For information about cURL, see

To run the cURL request examples shown in this guide on Mac OS® X, Linux, and Unix systems, copy each example directly to the command line or a script.

If you are using Microsoft Windows, you need to adjust the cURL examples to run them. See Convert cURL examples to run on Windows.

The following example shows a cURL command for sending an authentication request to the Rackspace Cloud Identity service.

Example: cURL command for sending a JSON request

$ curl \
       -X POST \
       -d '{"auth":{"RAX-KSKEY:apiKeyCredentials":{"username":"$APIAccessUserName","apiKey":"$apiKey"}}}' \
       -H "Content-type: application/json" | python -m json.tool

In this example, $apiKey is an environment variable that stores your API key value. Environment variables make it easier to reference account information in API requests, to reuse the same cURL commands with different credentials, and to keep sensitive information like your API key from being exposed when you send requests to Rackspace Cloud API services. For details about creating environment variables, see Configure environment variables.


The carriage returns in the cURL request examples use a backslash (\) as an line-contintuation symbol, which allows continuation of the command across multiple lines.

The cURL examples in this guide use the following command-line options.

-dSends the specified data in a POST request to the HTTP server. Use this option to send a JSON request body to the server.
-HSpecifies an extra HTTP header in the request. You can specify any number of extra headers. Precede each header with the -H option.

Common headers in Rackspace API requests are as follows:

Content-Type: Required for operations with a request body.

Specifies the format of the request body. Following is the syntax for the header where format is json:

Content-Type: application/json

X-Auth-Token: Required. Specifies the authentication token.

X-Auth-Project-Id: Optional. Specifies the project ID, which can be your account number or another value.

Accept: Optional. Specifies the format of the response body.

Following is the syntax for the header where the format is json, which is the default:

Accept: application/json
-iIncludes the HTTP header in the output.
-sSpecifies silent or quiet mode, which makes cURL mute. No progress or error messages are shown.

If your cURL command is not generating any output, try replacing the -s option with -i.
-TTransfers the specified local file to the remote URL.
-XSpecifies the request method to use when communicating with the HTTP server. The specified method is used instead of the default method, which is GET.

For commands that return a response, you can use json.tool to pretty-print the output. Append the following command to the cURL call:

 | python -m json.tool

To use json.tool, import the JSON module. For information about json.tool, see JSON encoder and decoder.

If you run a Python version earlier than 2.6, import the simplejson module and use simplejson.tool. For information about simplejson.tool, see simplejson encoder and decoder.

If you do not want to pretty-print JSON output, omit this code.


If your request includes the -i option to show header output, do not try to pretty-print the output. Header information is not in JSON format, and the API service returns an error if you specify json.tool.

Convert cURL examples to run on Windows

The cURL examples in the Rackspace API documentation use syntax supported on Mac OS X, Linux and UNIX systems. Microsoft Windows does not support the same format. However, you can run the examples on Windows after making the following changes:

  • Replace all the line-continuation backslash characters (\) with a caret (^), and remove any trailing spaces after the ^.
  • If an example includes JSON data, export the data to a text file. When you run the cURL command, use the @filename syntax to import the JSON data. Save the JSON data files in a directory, and run cURL commands from that directory.

The following example shows the cURL format for Linux and UNIX systems:

$ curl  \
      -X POST \
      -d '{"auth":{"RAX-KSKEY:apiKeyCredentials":{"username":"yourUserName","apiKey":"$apiKey"}}}' \
      -H "Content-type: application/json"

The following example shows the same request with the changes made for Windows systems:

$ curl  ^
      -X POST ^
      -d @credentials.txt  ^
      -H "Content-type: application/json"