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Using configuration data in DSC

eslesar|Last Updated: 4/3/2017
|
4 Contributors

Applies To: Windows PowerShell 4.0, Windows PowerShell 5.0

By using the built-in DSC ConfigurationData parameter, you can define data that can be used within a configuration. This allows you to create a single configuration that can be used for multiple nodes or for different environments. For example, if you are developing an application, you can use one configuration for both development and production environments, and use configuration data to specify data for each environment.

This topic describes the structure of the ConfigurationData hashtable. For examples of how to use configuration data, see Separating configuration and environment data.

The ConfigurationData common parameter

A DSC configuration takes a common parameter, ConfigurationData, that you specify when you compile the configuration. For information about compiling configurations, see DSC configurations.

The ConfigurationData parameter is a hasthtable that must have at least one key named AllNodes. It can also have one or more other keys.

Note: The examples in this topic use a single additional key (other than the named AllNodes key) named NonNodeData, but you can include any number of additional keys, and name them whatever you want.

$MyData = 
@{
    AllNodes = @()
    NonNodeData = ""   
}

The value of the AllNodes key is an array. Each element of this array is also a hash table that must have at least one key named NodeName:

$MyData = 
@{
    AllNodes = 
    @(
        @{
            NodeName = "VM-1"
        },


        @{
            NodeName = "VM-2"
        },


        @{
            NodeName = "VM-3"
        }
    );

    NonNodeData = ""   
}

You can add other keys to each hash table as well:

$MyData = 
@{
    AllNodes = 
    @(
        @{
            NodeName = "VM-1"
            Role     = "WebServer"
        },


        @{
            NodeName = "VM-2"
            Role     = "SQLServer"
        },


        @{
            NodeName = "VM-3"
            Role     = "WebServer"
        }
    );

    NonNodeData = ""   
}

To apply a property to all nodes, you can create a member of the AllNodes array that has a NodeName of *. For example, to give every node a LogPath property, you could do this:

$MyData = 
@{
    AllNodes = 
    @(
        @{
            NodeName     = "*"
            LogPath      = "C:\Logs"
        },


        @{
            NodeName     = "VM-1"
            Role         = "WebServer"
            SiteContents = "C:\Site1"
            SiteName     = "Website1"
        },


        @{
            NodeName     = "VM-2"
            Role         = "SQLServer"
        },


        @{
            NodeName     = "VM-3"
            Role         = "WebServer"
            SiteContents = "C:\Site2"
            SiteName     = "Website3"
        }
    );
}

This is the equivalent of adding a property with a name of LogPath with a value of "C:\Logs" to each of the other blocks (VM-1, VM-2, and VM-3).

Defining the ConfigurationData hashtable

You can define ConfigurationData either as a variable within the same script file as a configuration (as in our previous examples) or in a separate .psd1 file. To define ConfigurationData in a .psd1 file, create a file that contains only the hashtable that represents the configuration data.

For example, you could create a file named MyData.psd1 with the following contents:

@{
    AllNodes =
    @(
        @{
            NodeName    = 'VM-1'
            FeatureName = 'Web-Server'
        },

        @{
            NodeName    = 'VM-2'
            FeatureName = 'Hyper-V'
        }
    )
}

Compiling a configuration with configuration data

To compile a configuration for which you have defined configuration data, you pass the cofiguration data as the value of the ConfigurationData parameter.

This will create a MOF file for each entry in the AllNodes array. Each MOF file will be named with the NodeName property of the corresponding array entry.

For example, if you define configuration data as in the MyData.psd1 file above, compiling a configuration would create both VM-1.mof and VM-2.mof files.

Compiling a configuration with configuration data using a variable

To use configuration data that is defined as a variable in the same .ps1 file as the configuration, you pass the variable name as the value of the ConfigurationData parameter when compiling the configuration:

MyDscConfiguration -ConfigurationData $MyData

Compiling a configuration with configuration data using a data file

To use configuration data that is defined in a .psd1 file, you pass the path and name of that file as the value of the ConfigurationData parameter when compiling the configuration:

MyDscConfiguration -ConfigurationData .\MyData.psd1

Using ConfigurationData variables in a configuration

DSC provides three special variables that can be used in a configuration script: $AllNodes, $Node, and $ConfigurationData.

  • $AllNodes refers to the entire collection of nodes defined in ConfigurationData. You can filter the AllNodes collection by using .Where() and .ForEach().
  • Node refers to a particular entry in the AllNodes collection after it is filtered by using .Where() or .ForEach().
  • ConfigurationData refers to the entire hash table that is passed as the parameter when compiling a configuration.

Using non-node data

As we've seen in previous examples, the ConfigurationData hashtable can have one or more keys in addition to the required AllNodes key. In the examples in this topic, we have used only a single addiontal node, and named it NonNodeData. However, you can define any number of addiontal keys, and name them anything you want.

For an example of using non-node data, see Separating configuration and environment data.

See Also

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