Execute a PowerShell script as a standard monitor in SCOM

Custom monitors in SCOM may, unless the Authoring Console is used or custom XML employed, only execute VBScript. PowerShell scripts can still be executed though, as long as they’re Base64-encoded and wrapped in VBScript.

1. Write a PowerShell script that places its output on the console as easily-identifiable strings, the output from which can be easily parsed by VBScript, e.g.

   Success: 0
   Error message: Insufficient memory.

2. Encode the PowerShell script to Base64, where {Script} is the script:

   $Command = '{Script}'
   $EncodedCommand = [Convert]::ToBase64String([System.Text.Encoding]::Unicode.GetBytes($Command))
   $EncodedCommand > EncodedCommand.txt

3. Create the monitor, implementing a VBScript similar to that below, but inserting the contents of EncodedCommand.txt into the PsScript variable.

   PsScript=""
   Command="PowerShell.exe -EncodedCommand " & PsScript
   Set Shell=CreateObject("WScript.Shell")
   Set Executor=Shell.Exec(Command)
   Executor.StdIn.Close
   varPSResult=Executor.StdOut.ReadAll
   
   varSuccess=Mid(varPSResult, InStr(varPSResult, "Success: ") +
   Len("Success: "), 1)
   varErrorMessage=Right(varPSResult, Len(varPSResult) - (InStr(varPSResult,
   "Error message: ") + Len("Error message: ") - 1))
   
   Dim oAPI, oBag
   Set oAPI=CreateObject("MOM.ScriptAPI")
   Set oBag=oAPI.CreatePropertyBag()
   
   Call oBag.AddValue("Success", varSuccess)
   Call oBag.AddValue("Error message", varErrorMessage)
   Call oAPI.Return(oBag)
   		

4. Configure the healthy, unhealthy and other components as appropriate.