Executing WFA workflows using REST

NetApp’s Workflow Automation (WFA) tool is a valuable asset for providing easily consumed scriptable tasks to perform nearly any function that storage administrators require.  For administrators who want to get out of the business of doing mundane tasks, like provisioning generic volumes, adjusting volume sizes, etc., WFA gives you the ability to surface those operations to storage consumers and have them do the work for themselves.

WFA can also play a part in a larger scheme of workflows that can be orchestrated by other software, for example VMware’s vCAC, Puppet, Chef, Microsoft Orchestrator, etc.  This leaves the power (and details) of how to automate the task with the storage team, but enables the IT organization to leverage storage resources in a programmatic manner.  This is done using the REST interface.

To access the REST interface, simply browse to your WFA server, but instead of “http://your_wfa_host/wfa” for the URL, use “http://your_wfa_host/rest/docs“, which will bring you to the documentation for the rest interface.

If you are prompted for credentials, use the same username/password combination you would normally use to connect to WFA. You can select resources, such as workflows, which will then provide the documentation for how to interact with workflow.

As you can see in the screenshot above, we have a “/workflows” url (which the full URL would be http://your_wfa_host/rest/workflows), which can be called using the GET method. This will return a list of all of the workflows available. Optionally, a name parameter can be passed which will search for workflows that match the name provided. Let’s try this using the “Create a Clustered Data ONTAP Volume” workflow, a part of the base WFA install.

The above screenshot is of the XML returned from the REST query. I’ve collapsed some of the input and return parameters to show the bottom part of the result, which provides links to the URLs for executing the workflow. Going back to our documentation, let’s look at what it says about the jobs action…

It is expected to be called via a POST method, with the content being the workflowInput XML. This XML is defined by following the link provided, which shows an example:

So, what have we learned so far?

• The WFA rest interface is accessible at http://your_wfa_host/rest
• The workflows can be searched by name using the url template http://your_wfa_host/rest/workflows?name=some%20workflow%20name
• Once the workflow is found, the response contains the REST url for executing the workflow, which should be called using a POST operation in the workflowInput XML format

What happens when we execute a WFA workflow using REST? Well, assuming the inputs are valid, once the /rest/{workflow_uuid}/jobs URL has been successfully invoked a JobRepresentation will be returned. This contains, among other things, the jobId for the workflow execution that was just requested.

By requesting, using the GET method, the URL for the job status we can determine when the workflow has finished execution. The URL template for this is: http://your_wfa_host/rest/workflows/{workflow_uuid}/jobs/{job_id}. Now, by periodically checking this url, we can determine when WFA has finished execution.

Let’s put this all together using Powershell (version 4 has native cmdlets for executing REST):

The above script is about 90 lines, but has some customization specific to the NetApp WFA workflow we are executing (“Create a Clustered Data ONTAP Volume”). For example, I’m using the returned parameters from WFA to provide information back to the console. The majority of the code can be reused to execute any WFA workflow using REST.

Questions and comments are always welcome below. If you have any suggestions for, or need help with, NetApp/VMware integration, automation, and solutions, please let me know using the comments!