Configuration Data for DSC not in JSON

DSC
1

Hello, I would like to know why the Configuration Data file(.psd1) for the DSC is written in PSON (Powershell) and not in JSON which is more common.
If I would like to create such a file through a script I need to use some unsupported Functions like ConvertTo/FROM-PSON which I have found on the Internet, instead I could use the already supported ConvertTO/FROM- JSON.
Well at least they could give the ConvertTo/From-PSON out of the box as they give the JSON onces.

2

The .psd1 file is a PowerShell Module Manifest file. Modules are the recommended way PowerShell functionality is delivered.

Why would a PowerShell file be written in JSON?

DSC is a PowerShell extension - its not really reasonable to expect it to be written in anything but PowerShell

3

DSC only requires you to pass in a Hashtable object for the -ConfigurationData parameter when you call the config. It doesn’t care how you store that hashtable on disk; there’s no reason you can’t use JSON.

There’s one slight snag, which is that ConvertFrom-Json will give you PSCustomObjects instead of Hashtables, so you need a bit of code to make that conversion before passing your configuration data to a DSC config:

$ht = @{
    AllNodes = @(
        @{
            NodeName = 'Node1'
            Whatever = 'Something'
        }
    )

    NonNodeData = @{
        SomeOtherThing = 'Whatever'
        SomeArray = @()
    }
}

# Simulating saving the JSON to disk and then reloading it
$object = $ht | ConvertTo-Json | ConvertFrom-Json

# Now $object is a pscustomobject, as are any nested hashtables inside its structure

function ConvertPSObjectToHashtable
{
    param (
        [Parameter(ValueFromPipeline)]
        $InputObject
    )

    process
    {
        if ($null -eq $InputObject) { return $null }

        if ($InputObject -is [System.Collections.IEnumerable] -and $InputObject -isnot [string])
        {
            $collection = @(
                foreach ($object in $InputObject) { ConvertPSObjectToHashtable $object }
            )

            Write-Output -NoEnumerate $collection
        }
        elseif ($InputObject -is [psobject])
        {
            $hash = @{}

            foreach ($property in $InputObject.PSObject.Properties)
            {
                $hash[$property.Name] = ConvertPSObjectToHashtable $property.Value
            }

            $hash
        }
        else
        {
            $InputObject
        }
    }
}

$converted = ConvertPSObjectToHashtable $object

# $converted is now equivalent to the original $ht, and can be passed into your configuration.

SomeDSCConfiguration -ConfigurationData $converted
4

Thanks a lot, great answer like always!

5

^bump^

As the response above illustrates, JSON is just tons easier to work with than nested hash-tables - for filtering, saving to files/db, getting from a web-service, etc.
Sure would help with some of my tfs deployment scripts.