PowerShell Jobs

Scope

• JobScheduler offers PowerShell as a language for implementation of Jobs
• PowerShell Jobs have to been seen as the analogy for the Shell Jobs, even though there are some differences between Shell and PowerShell Jobs (see PowerShell as a Shell)
• The decision to include PowerShell as a language for JobScheduler (among others) is in the same line with the development of Microsoft programming languages
• PowerShell Jobs can only be run on Agents and not on the Master

Feature Availability

FEATURE AVAILABILITY STARTING FROM RELEASE 1.10.5

PowerShell as a Shell

As mentioned before, Powershell Jobs should be seen as the analogy for Shell Jobs in the future. That means, every Shell job should be able to be (with any or few changes) converted into a PowerShell job. 

Nevertheless, there are some compatibility issues as described below.

Examples

Example: PowerShell as a Shell

Example 1: A simple PowerShell job with some scripting analogue to basic Shell jobs might look like this:

<?xml version="1.0" encoding="ISO-8859-1"?>
<job process_class="my_Agent">
    <script language="powershell">
echo "job is starting"
sleep 10
$files = dir *
echo $files
echo "job is finishing"
    </script>
    <run_time />
</job>

Example 2: A basic PowerShell job including a call of a function might look like this:

<?xml version="1.0" encoding="ISO-8859-1"?>
<job  process_class="my_Agent">
    <script  language="powershell">

	function get_files($directory){
		echo "entering function get_files"
		return get-childitem $directory
	}
	
	echo "job is starting"
	sleep 10
	$files = get_files "my_directory"
	echo $files
	echo "job is finishing"
	
    </script>
    <run_time />
</job>

Example: PowerShell API Jobs

A basic API Job might look like this:

<?xml version="1.0" encoding="ISO-8859-1"?>
<job process_class="my_Agent">
    <script language="powershell">
	function spooler_process()
	{
		$spooler_log.info("job is starting")
		$files = get-childitem dir *
		echo $files 
		$spooler_log.info("job is finishing")
		return $false
	}
    </script>
    <run_time />
</job>

Example: Combination of both (PowerShell Job with Monitor as a Pre-Processing job)

This PowerShell job contains a job with a  pre-processing Monitor script (API job) that is executed before the job script (the shell job) is executed:

<?xml version="1.0" encoding="ISO-8859-1"?>

<job  process_class="my_Agent">
    <script  language="powershell">

echo "job is starting"
sleep 10
echo "job is finishing"

    </script>
    <monitor  name="process_powershell" ordering="0">
        <script  language="powershell">
            <![CDATA[
		function spooler_process_before()
		{
			# check for a "go" file that is required to start the job
			$rc = (Test-Path -Path "/tmp/go.txt" -PathType Leaf)
			echo ".. looking up go file: $rc"
			return $rc
		}
            ]]>
        </script>
    </monitor>
    <run_time />
</job>

Example: PowerShell Job with different outputs

The following job shows how to set different outputs for PowerShell such as:

<?xml version="1.0" encoding="ISO-8859-1"?>

<job  process_class="my_Agent" stop_on_error="no">
    <settings >
        <log_level ><![CDATA[debug1]]></log_level>
    </settings>

    <script  language="powershell">
        <![CDATA[
# Standard PowerShell verbose setting is considered for log output:
$VerbosePreference = "continue"
Write-Verbose "job: this is some verbose output"

# Standard PowerShell debug setting:
$DebugPreference = "continue"
# In addition the current log level of the job is applied, e.g. log level "debug1" logs debug messages
Write-Debug "job: this is some debug output"

# creates a warning in the log
Write-Warning "job: this is a warning"

# can be used to throw an error
# Write-Error "job: this is an error"

# This does not work: Use of Write-Host is not allowed
# Write-Host "job: this is some output"
        ]]>
    </script>

    <run_time />
</job>

Extras: PowerShell CLI for Powershell Jobs

The integration of the PowerShell CLI into PowerShell jobs is available as well. A basic job using the PowerShell CLI might look like this:

 <job process_class="my_Agent">
 <script language="powershell">
 <![CDATA[

Import-Module JobScheduler
show-status

 ]]>
 </script>
<run_time />

Differences between PowerShell and Shell

As mentioned before, Powershell Jobs should be seen as the analogy for Shell Jobs in the future. That means, every Shell job should be able to be (with any or few changes) converted into a PowerShell job. 

Nevertheless, there are some compatibility issues as described below.

Calling Order parameters or Job parameters

# Example Shell: 
myscript.cmd %SCHEDULER_PARAM_NAME1%

# Example PowerShell: 
myscript.cmd $env:SCHEDULER_PARAM_NAME1

Returning a parameter an its value to an Order

# Example Shell: 
echo NAME1 = VALUE1 >> %SCHEDULER_RETURN_VALUES%

# Example PowerShell: 
echo "NAME1 = VALUE1" >> $env:SCHEDULER_RETURN_VALUES
$spooler_task.order.params.set_value( 'NAME1', 'VALUE1')

Exit Code Handling

The following example throws no error in a Shell job but it breaks at line 2 and ends in an error for a PowerShell job:

echo "job is starting"
abcde
echo "job is finishing"

The same example would be working in PowerShell the following way:

echo "job is starting"
try { abcde }
catch {}
echo "job is finishing"