Runbook output and messages

Most automation runbooks will have some form of output such as an error message to the user or a complex object intended to be consumed by another workflow. Windows PowerShell provides multiple streams to send output from a workflow. Service Management Automation works with each of these streams differently, and you should follow best practices for how to use each when you're creating a runbook.

The following table provides a brief description of each of the streams and their behavior in the Management Portal both when running a published runbook and when testing a runbook. Further details on each stream are provided in the subsequent sections.

Output stream

The Output stream is intended for output of objects created by a workflow when it runs correctly. In Automation, this stream is primarily used for objects intended to be consumed by parent runbooks that call the current runbook. When you call a runbook inline from a parent runbook, it returns data from the output stream to the parent. You should only use the output stream to communicate general information back to the user if you know the runbook will never be called by another runbook. As a best practice, however, you should typically use the Verbose Stream to communicate general information to the user.

You can write data to the output stream using Write-Output or by putting the object on its own line in the runbook.

#The following lines both write an object to the output stream.
Write-Object -InputObject $object
$object

Output from a function

When you write to the output stream in a function that is included in your runbook, the output is passed back to the runbook. If the runbook assigns that output to a variable, then it isn't written to the output stream. Writing to any other streams from within the function will write to the corresponding stream for the runbook.

Consider the following sample runbook.

Workflow Test-Runbook
{
   Write-Verbose "Verbose outside of function"
   Write-Output "Output outside of function"
   $functionOutput = Test-Function

   Function Test-Function
   {
      Write-Verbose "Verbose inside of function"
      Write-Output "Output inside of function"
   }
}

The output stream for the runbook job would be:

Output outside of function

The verbose stream for the runbook job would be:

Verbose outside of function
Verbose inside of function

The $functionOutput variable would have the value:

Output inside of function

Declare output data type

A workflow can specify the data type of its output using the OutputType attribute. This attribute has no effect during runtime, but it provides an indication to the runbook author at design time of the expected output of the runbook. As the toolset for runbooks continues to evolve, the importance of declaring output data types at design time will increase in importance. As a result, it's a best practice to include this declaration in any runbooks that you create.

The following sample runbook outputs a string object and includes a declaration of its output type. If your runbook outputs an array of a certain type, then you should still specify the type as opposed to an array of the type.

Workflow Test-Runbook
{
   [OutputType([string])]

   $output = "This is some string output."
   Write-Output $output
}

Message streams

Unlike the output stream, message streams are intended to communicate information to the user. There are multiple message streams for different kinds of information, and each is handled differently by Automation.

Select the required tab to know more about these message streams:

#The following lines create a warning message and then an error message that will suspend the runbook.

$ErrorActionPreference = "Stop"
Write-Warning -Message "This is a warning message."
Write-Error -Message "This is an error message that will stop the runbook because of the preference variable."

#The following line creates a verbose message.

Write-Verbose -Message "This is a verbose message."

Progress records

If you configure a runbook to log progress records (on the Configure tab of the runbook in the Management Portal), then a record will be written to the job history before and after each activity is run. In most cases, you should keep the default setting of not logging progress records for a runbook in order to maximize performance. Turn on this option only to troubleshoot or debug a runbook. When testing a runbook, progress messages aren't displayed even if the runbook is configured to log progress records.

The Write-Progress cmdlet isn't valid in a runbook since it is intended for use with an interactive user.

Preference variables

Windows PowerShell uses preference variables to determine how to respond to data sent to different output streams. You can set these variables in a runbook to control how it will respond to data sent into different streams.

The following table lists the preference variables that can be used in runbooks with their valid and default values.

The following table lists the behavior for the preference variable values that are valid in runbooks.

Retrieving Runbook Output and Messages

Management portal

You can view the details of a runbook job in the Management Portal from the Jobs tab of a runbook. The Summary of the job will display the input parameters and the Output Stream in addition to general information about the job and any exceptions if they occurred. The History will include messages from the Output Stream and Warning and Error Streams in addition to the Verbose Stream and Progress Records if the runbook is configured to log verbose and progress records.

Windows PowerShell

In Windows PowerShell, you can retrieve output and messages from a runbook using the Get-SmaJobOutput cmdlet. This cmdlet requires the ID of the job and has a parameter called Stream where you specify which stream to return. You can specify Any to return all streams for the job.

The following example starts a sample runbook and then waits for it to complete. Once completed, its output stream is collected from the job.

$webServer = 'https://MyServer'
$port = 9090
$runbookName = "Test-Runbook"
$job = Start-SmaRunbook -WebServiceEndpoint $webServer -Port $port -Name $runbookName

$doLoop = $true
While ($doLoop) {
   $job = Get-SmaJob -WebServiceEndpoint $webServer -Port $port -Id $job.Id
   $status = $job.Status
   $doLoop = (($status -ne "Completed") -and ($status -ne "Failed") -and ($status -ne "Suspended") -and ($status -ne "Stopped")
}

Get-SmaJobOutput -WebServiceEndpoint $webServer -Port $port -Id $job.Id -Stream Output

Next steps

Author automation runbooks.