DSC Configuration Data

Pubblicato: giugno 2013

Aggiornamento: giugno 2013

Si applica a: Windows PowerShell 4.0, Windows PowerShell 5.0

In Windows PowerShell Desired State Configuration (DSC), it is possible to separate configuration data from the logic of your configuration. This has the following advantages:

• It allows you to reuse your configuration data for different resources, nodes, and configurations.

• Configuration logic is more reusable if it does not contain hard-coded data. This is similar to good scripting guidelines for functions.

• If some of the data needs to change, you can make the changes in one location, thereby saving time and reducing errors.

Rules and options for separating data

Below is a demonstration of how you can separate out configuration data.

1. Define a hash table. In the example below, we named it $ConfigData, but you can give it any name you choose.

2. Inside the hashtable, define at least one array, which you must name $AllNodes. You are free to define additional arrays inside the hash table, if you need them for other uses in your script.

3. Inside the $AllNodes array, define zero or more hash tables that will contain configuration data.

4. Each of the hash tables that are direct elements of $AllNodes must have at least one property called NodeName, and the values must be represented as a string.

5. When you invoke your configuration, pass the $AllNodes array to it by using the automatic ConfigurationData parameter that is built-in and available for use with all configurations.

6. Within the configuration, access the configuration data array by using the $AllNodes automatic variable.

7. You can use the keyword Where to search the properties of the hash tables that form the $AllNodes array.

8. After you filter with Where, you can access the selected set of hash tables by using the $SelectedNodes automatic variable.

9. The $AllNodes array can have a hash table where the NodeName property is set to "*", so that any properties you define in this hash table will be available to all nodes. When a node-specific hash table (that is, a hash table with NodeName set to a string other than "*") defines a property with the same name as a property defined in the "*" hash table, the value of the property as defined in the node-specific hash table overrides the value defined in the "*" hash table.

$ConfigData = @{
    AllNodes = @( 
             # NodeName \\"*\\" applies globally to all nodes in this array
             @{ NodeName = "*"; RecurseValue = $true },
             @{ NodeName = "localhost"; Role = "Web"; RolesToBePresent = "Web-Server"; 
                SourceRoot = "\\Server106\source\presentation\"; Version = "1.0"; 
                WebDirectory = "c:\inetpub\wwwroot\"; RecurseValue = $false; }
    );

    # Environmental configuration for the DHCP settings
    # These settings can be generic configuration data that is not node specific. 
    DHCPConfigEnv = @{
                    ComputerName = "((Get-VM dc | Select-Object -ExpandProperty networkadapters).ipaddresses)[0]"
                    DNSIPAddress = $dcIPAddress
                    DNSName = "dc.fourthcoffee.com"
                    ScopeName = "PowerShellSummit2013"
                    ScopeID = "192.168.10.0"
                    StartRange = "192.168.10.3"
                    EndRange = "192.168.10.254"
                    SubnetMask = "255.255.255.0"
                    LeaseDurationDays = 1
                    DomainName = $DomainName
    };
}

Configuration CloudService
{   # The $AllNodes and $Node (current node) variables are automatic variables
    Node $AllNodes.Where{$_.Role -eq "Web"}.NodeName {
        WindowsFeature IIS
        { Ensure = "Present"; Name = $Node.RolesToBePresent }
    }
}
 
CloudService –ConfigurationData $ConfigData