Powershell script to read multiple variable from file

Question

I have a script which invokes a session on remote computer and run a script.

$pw = convertto-securestring -AsPlainText -Force -String '$(PWD_vSphere_AdminUser)'
$cred = new-object -typename System.Management.Automation.PSCredential -argumentlist ".\Administrator",$pw
Invoke-Command -Credential $Cred -ComputerName 'testcomputer' -FilePath "./addvm.ps1"

This works fine. Now I have to run it on multiple computers. I want to read -ComputerName values from a tfvars file (json format). where name = "testcomputer" occurring multiple times. I want to read this "name" value from tfvars file (json format) and run my script for each "name" value.

    {
  "vm": [
    {
      "testcomputer": [
        {
          "memory": "4096",
          "name": "testcomputer",
          "time_zone": "020"
        }
      ],
      "testcomputer1": [
        {
          "memory": "4096",
          "name": "testcomputer1",
          "time_zone": "020"
        }
      ],
      "testcomputer2": [
        {
          "memory": "4096",
          "name": "testcomputer2",
          "time_zone": "020"
        }
      ]
    }
  ]
}

I have read this Powershell retrieving a variable from a text file but that dosen`t solve much about occurrence.

Please add the code you're using to read the file and to then call Invoke-Command — Santiago Squarzon
– Santiago Squarzon, Commented Mar 28, 2022 at 21:08
@SantiagoSquarzon I dont have a code to read the file yet. I am new in powershell. I wrote code only for a single Invoke-Command. — Ashish Mishra
– Ashish Mishra, Commented Mar 28, 2022 at 21:11
The file you're showing us does literally look like the one you've shared? Do you have a way to modify the output of the process generating this file for a standard format like Json, Xml or CSV? — Santiago Squarzon
– Santiago Squarzon, Commented Mar 28, 2022 at 21:14
yes this is actual file, its a terraform variable file. test.tfvars — Ashish Mishra
– Ashish Mishra, Commented Mar 28, 2022 at 21:18
According to this answer stackoverflow.com/a/55059439/15339544 you can have terraform output as Json and I would recommend you to do so. The file you currently have would require unnecessary parsing. — Santiago Squarzon
– Santiago Squarzon, Commented Mar 28, 2022 at 21:46

Vasil Nikolov · Accepted Answer · 2022-03-28 23:41:10Z

0

If what you share is really the input you will get literally, one way to deal with it would be to use Regex, but if can somehow input that as an object, either JSON or XML or whatever that can be read and properly converted in to an object, you should do that instead of Regex.

As of regex, reading from literally the input you showed , you can do something like this :

$inputVar = @"
vm = {
    "testcomputer" = {
        name = "testcomputer"
        memory = "4096"
        time_zone = "020"
    }
    "testcomputer1" = {
        name = "testcomputer1"
        memory = "4096"
        time_zone = "020"
    }
    "testcomputer2" = {
        name = "testcomputer2"
        memory = "4096"
        time_zone = "020"
    }
}
"@


#the matching pattern.
$regexFormat = '(?<=name = ").[^"]*'

#Grab only the matching pattern items.
$computerList = [regex]::Matches($inputVar, $regexFormat) | ForEach-Object { $_.value }

foreach ($computer in $computerList) {

    $pw = convertto-securestring -AsPlainText -Force -String '$(PWD_vSphere_AdminUser)'
    $cred = new-object -typename System.Management.Automation.PSCredential -argumentlist ".\Administrator", $pw
    Invoke-Command -Credential $Cred -ComputerName $computer -FilePath "./addvm.ps1"

}

I have made a literally input with the $inputVar just to show the example, and then you can do foreach loop to run your code for each computer.

answered Mar 28, 2022 at 23:41

Vasil Nikolov

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3 Comments

Ashish Mishra Over a year ago

Terraform is not taking input syntax. So I have changed the tfvars as json format. Modified the question now.

Ashish Mishra Over a year ago

also can I use a file as for $computerList. Like below $computerList = Get-Content -Path .\a.tfvars | [regex]::Matches($inputVar, $regexFormat) | ForEach-Object { $_.value }

Ashish Mishra Over a year ago

That worked. Thanks very much. Just modified like below. $inputVar = Get-Content -Raw -Path a.tfvars #Grab only the matching pattern items. $computerList = [regex]::Matches($inputVar, $regexFormat) | ForEach-Object { $_.value }

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