Passing variables to Invoke-Command, inside inlineScript, inside workflow

Question

I'm trying to create a script that connects to various servers, should attach a PSDrive and copy over files. The problem resides in that I an unable to pass the variable into the Invoke-Command script-block.

workflow kopijobb {
    param ([string[]]$serverList, $creds, $basePath)

    foreach -parallel ($server in $serverList){

        # Use the sequence keyword, to ensure everything inside of it runs in order on each computer.
        sequence {

            #Use the inlinescript keyword to allow PowerShell workflow to run regular PowerShell cmdlets
            inlineScript{

                $path = $using:basePath

                Write-Host "Starting $using:server using $path"
                #Create session for New-PSSession
                $session = New-PSSession -ComputerName $using:server -Credential $using:creds

                # Copy Java and recreate symlink
                Invoke-Command -Session $session -ScriptBlock {

                    # Make a PSDrive, since directly copying from UNC-path doesn't work due to credential-issues
                    New-PSDrive -Name N -PSProvider FileSystem -root $using:path -Credential $using:creds | out-null

I pass the network path to $basePath, and I'm able to read it inside the inlineScript block (where I have tried storing it in a new variable to test), but once I try accessing it in the New-PSDrive command, the variable is suddenly empty/unreachable, and the mounting of the drive fails with the error Cannot bind argument to parameter 'Root' because it is null.

I'm at a loss to why this fails, so I'm turning to the collective wisdom here instead.

Yes, problem is, then the $using:creds variable becomes the bottleneck in New-PSDrive (can't access the drive without logging in). :( — Snorre Selmer
– Snorre Selmer, Commented May 8, 2018 at 11:45
I am afraid that handing credentials over to the other machine using $creds does not work by design. So you are absolutely right to hand over user and pwd seperately. Dont use $using outside the invoke-block. It is meant to be used inside the script block to access the variables from the calling maching. — TomG
– TomG, Commented May 9, 2018 at 13:12
Passing credentials as an argument worked fine. As for the $using, I tried all kinds of variations, but my solution below was the only way I got it to work.once I finish the other projects I'm working on I will revisit this script to see if I can improve on it. — Snorre Selmer
– Snorre Selmer, Commented May 9, 2018 at 15:48

Snorre Selmer · Accepted Answer · 2018-05-08 13:43:25Z

2

If feels embarrassing to answer my own question, especially on the same day, but I bumped into a PowerShell guru at work and he took one glance at the script and saw the problem:

I had to add -Args to the Invoke-Command

            Invoke-Command -Session $session -ScriptBlock {
                param($srv,$login,$path,$...)

                #Make a PSDrive, since directly copying from UNC-path doesn't work due to credential-issues
                New-PSDrive -Name N -PSProvider FileSystem -root $path -Credential $login | out-null
            } -Args $using:server,$using:creds,$using:basePath,$using:...

This does of course mean that I had to import all the needed arguments from the top level into the workflow, and then into the Invoke-Command.

answered May 8, 2018 at 13:43

Snorre Selmer

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3 Comments

Maximilian Burszley Over a year ago

You should be able to utilize the $using: scope directly in your scriptblock without the need for an arglist.

Snorre Selmer Over a year ago

Should? Maybe. Could? Not a chance! I tried all kinds of variations, nothing else worked. It's like the scriptBlock was isolated from everything before it.

karatedog Over a year ago

@MaximilianBurszley I have completely restructured my code into Print Driven Development mode and I can assure you that variables pass from Workflow to InlineScript but they don't pass from InlineScript into Invoke-Command even if I create a new variable in the InlineScript scope using $Using a variable from the outer (Workflow) scope, and then I try to use that InlineScript scope variable with $Using in the Invoke-Command scope. (Also, that is -ArgumentList for me, not -Args)

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