In my last article, I introduced you to a collection filtering option that you may not have been familiar with, the Where() method. This and the related ForEach() method I will cover today were introduced in PowerShell v4 to support Desired State Configuration (DSC). You might have a configuration file like this:

@{
    #Node specific data
    #allnodes is an array of hashtables, one per node
    AllNodes = @( 
       @{NodeName = "*"
         Features = @("Windows-Server-Backup","PowerShell","SNMP-Service")
         FeaturesRemove = @("Telnet-Client","PowerShell-v2","BranchCache")
         },
       @{NodeName = "SRV1"; Role = "FilePrint","Test"},
       @{NodeName = "SRV2"; Role = "Web"}
    )

    #non-node Specific data. No code allowed
    NonNodeData = @{Services = "bits","remoteregistry","wuauserv"}
}

In the configuration, you can use the collection filtering method.

Node $allnodes.Where({ $_.role -eq 'FilePrint' }).Nodename {
    WindowsFeature FileServices {
        Name                 = "File-Services"
        Ensure               = "Present"
        IncludeAllSubFeature = $True
    }
    WindowsFeature PrintServices {
        Name                 = "Print-Services"
        Ensure               = "Present"
        IncludeAllSubFeature = $True
    }
} #close node