[PowerShell] Script to restart a service and its dependents (and their dependents)

Question

I am trying to write a PowerShell script that will restart the SNMP Service on a server.  The server in question is an HP server that has the various HP Insight agents installed, and some of these depend on the SNMP Service.  One of these services
also depends on one of the other HP Insight services (that in turn depends on SNMP Service).
I can easily write a script that stops and starts the specific services in order, but I don't want to do that.  I like to create scripts that are as flexible as possible.  In this case, I'd like to write a script that takes a service name as input
and can restart that service, including any dependents (and dependents of those dependents, and dependents of those dependents).  They way to do this seems to be recursion, but I simply cannot get it to work correctly.  Here is what I have so far
(just trying to get the services to stop in the correct order):
$MainServiceName = "SNMP"
$ServiceInput = ""
$CurrentService = ""
$Service = ""
function Custom-Stop-Service ($ServiceInput)
Write-Host "Name of `$ServiceInput: $($ServiceInput.Name)"
Write-Host "Number of dependents: $($ServiceInput.DependentServices.Count)"
If ($ServiceInput.DependentServices.Count -gt 0)
ForEach ($Service in $ServiceInput.DependentServices)
Write-Host "Dependent of $($ServiceInput.Name): $($Service.Name)"
If ($Service.Status -eq "Running")
Write-Host "$($Service.Name) is running."
$CurrentService = Get-Service -Name $Service.Name
Custom-Stop-Service $CurrentService
Write-Host "Stopping service $($CurrentService.Name)"
Stop-Service -Name $CurrentService.Name -Force
Else
Write-Host "$($Service.Name) is stopped."
Else
Write-Host "Stopping service $($ServiceInput.Name)"
Stop-Service -Name $ServiceInput.Name
$MainService = Get-Service -Name $MainServiceName
If ($MainService.Status -eq "Stopped")
Write-Host "Service $($MainService.Name) is already stopped."
Else
Custom-Stop-Service $MainService
However, it doesn't work like I expect.  Firstly, it never attempts to stop the SNMP service itself.  Secondly while it does seem to stop all the dependents of SNMP correctly, it tries to stop CqMgHost twice.  Here is the output:
PS C:\Scripts> .\restart_service.ps1
Name of $ServiceInput: SNMP
Number of dependents: 4
Dependent of SNMP: CqMgHost
CqMgHost is running.
Name of $ServiceInput: CqMgHost
Number of dependents: 0
Stopping service CqMgHost
WARNING: Waiting for service 'HP Insight Foundation Agents (CqMgHost)' to finish stopping...
WARNING: Waiting for service 'HP Insight Foundation Agents (CqMgHost)' to finish stopping...
WARNING: Waiting for service 'HP Insight Foundation Agents (CqMgHost)' to finish stopping...
WARNING: Waiting for service 'HP Insight Foundation Agents (CqMgHost)' to finish stopping...
Stopping service CqMgHost
Dependent of SNMP: CqMgStor
CqMgStor is running.
Name of $ServiceInput: CqMgStor
Number of dependents: 1
Dependent of CqMgStor: CqMgHost
CqMgHost is stopped.
Stopping service CqMgStor
Dependent of SNMP: CqMgServ
CqMgServ is running.
Name of $ServiceInput: CqMgServ
Number of dependents: 1
Dependent of CqMgServ: CqMgHost
CqMgHost is stopped.
Stopping service CqMgServ
WARNING: Waiting for service 'HP Insight Server Agents (CqMgServ)' to finish stopping...
WARNING: Waiting for service 'HP Insight Server Agents (CqMgServ)' to finish stopping...
Dependent of SNMP: CpqNicMgmt
CpqNicMgmt is running.
Name of $ServiceInput: CpqNicMgmt
Number of dependents: 1
Dependent of CpqNicMgmt: CqMgHost
CqMgHost is stopped.
Stopping service CpqNicMgmt
Can someone suggest a different script or changes to my script so that it will do what I want?  I know that "Stop-Service -Name SNMP -Force" will work but there are two problems with this: 1) it doesn't record the stop events for the dependents in the
Event Viewer and 2) it doesn't work in reverse ("Start-Service -Name SNMP -Force" nor "Restart-Service -Name SNMP -Force" restart the main service and the other services that depend on SNMP that were stopped).
I'm a little surprised that Restart-Service doesn't behave like the restart function in the Services MMC does, where it easily and reliably handles the stops and starts of not only the service itself, but dependent services and also properly does event logging.

Answer 1

I decided to try to understand why you see layers of dependencies.  I found that on WS2008 R2 HP managemnet does have a second layer.  It does not incluse anything but subservices from HP>  VSC is not  a dependency and, from my research,
should not ever be a dependency.  Of course this does not stop someone from making it a dependency which could create issues.
Here is a recursive function that will display all dependencies of any service or all services,
The code returns the service names in order and can be used to restart all services in dependent order.
function Get-Depends{
[CmdLetBinding()]
Param(
$servicename='SNMP',
$level = 0,
[switch]$infoonly
try{
Write-Verbose $($("`t" * $level)+$servicename)
$servicename
$services=get-service $servicename -ea stop | where{$_.dependentservices}|select -expand dependentservices
if($services){
$services | %{Get-Depends $($_.Name) ($level+1) }
catch{
$_
$depends=Get-Depends -v
The verbose switch displays a hierarchical display of names to ilustrate the dependencies.
jv