Running powershell script on asp.net site

Question

I am trying to run a powershell script and have it output to my asp.net site. I have made it work with a very simple script where the only command in the script was

Get-Service | Out-String

and this output onto my site everything I expected

but when I use the script I actually want info from it doesn't output anything I can tell it runs (or trys to run) because when my site hits the code that invokes the script it hangs about 10 seconds.

The script I am trying to run is

$user = "user"
$token = "token"

$base64AuthInfo = [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes(("{0}:{1}" -f $user,$token)))

$result = Invoke-WebRequest -Method Get -Uri 'https://site.vsrm.visualstudio.com/defaultcollection/product/_apis/release/releases?definitionId=1&api-version=3.0-preview.2&$expand=environments' -ContentType "application/json" -Headers @{Authorization=("Basic {0}" -f $base64AuthInfo)}

$releaseArr = $result.Content | ConvertFrom-Json
[System.Collections.ArrayList]$enviromentName = @()
[System.Collections.ArrayList]$latestRelease = @()


foreach($env in $releaseArr.value[0].environments)
{
    $enviromentName.Add($env.name) | Out-Null
}


foreach($releaseValue in $releaseArr.value)
{
    For($i = 0; $i -lt $enviromentName.Count; $i++)
    {
        if($latestRelease[$i] -eq $null)
        {
            foreach($release in $releaseValue.environments)
            {
                if($release.name -eq $enviromentName[$i] -and $release.status -eq "succeeded")
                {
                    $latestRelease.Add($releaseValue.name) | Out-Null
                }
            }
        }
    }
}

For($i = 0; $i -lt $enviromentName.Count; $i++)
{
    Write-Host $enviromentName[$i] " : " $latestRelease[$i]
}

I know this script runs and outputs, but is there some code in this script that would cause it to not output properly.

The code in my asp.net site I am using to call the script is

ResultBox.Text = string.Empty;

        // Initialize PowerShell engine
        var shell = PowerShell.Create();

        // Add the script to the PowerShell object
        shell.Commands.AddScript(@"C:\Users\user\Desktop\script.ps1");

        // Execute the script
        var results = shell.Invoke();

        // display results, with BaseObject converted to string
        // Note : use |out-string for console-like output
        if (results.Count > 0)
        {
            // We use a string builder ton create our result text
            var builder = new StringBuilder();

            foreach (var psObject in results)
            {
                // Convert the Base Object to a string and append it to the string builder.
                // Add \r\n for line breaks
                builder.Append(psObject.BaseObject.ToString() + "\r\n");
            }

            // Encode the string in HTML (prevent security issue with 'dangerous' caracters like < >
            ResultBox.Text = Server.HtmlEncode(builder.ToString());
        }

Why are you using PowerShell to call the API from a website? You could just invoke the REST methods directly in your application. — Daniel Mann
– Daniel Mann, Commented Apr 7, 2017 at 17:19
we already have this script created and were looking for a way we could use the already existing script instead of recreating it — Nick
– Nick, Commented Apr 7, 2017 at 17:21
I recommend that you can consider this package nuget.org/packages/…, it is easy. — starian chen-MSFT
– starian chen-MSFT, Commented Apr 10, 2017 at 2:58

omniomi · Accepted Answer · 2017-04-07 20:54:48Z

Change "Write-Host" to "Write-Output." Write-Host only outputs to interactive consoles.

You can see this in action:

Make a new PowerShell file and add a write-host statement to it:

[nick@nick-lt temp]$ New-Item -Type File -Path .\example.ps1 -Force
[nick@nick-lt temp]$ Set-Content .\example.ps1 "Write-Host 'Hello World'"

Then try and set a variable to the result of the script:

[nick@nick-lt temp]$ $what = .\example.ps1
Hello World
[nick@nick-lt temp]$ $what
[nick@nick-lt temp]$

Hello World shows up when the script executes but the variable is empty.

Now change it to write-output:

[nick@nick-lt temp]$ Set-Content .\example.ps1 "Write-Output 'Hello World'"
[nick@nick-lt temp]$ $what = .\example.ps1
[nick@nick-lt temp]$ $what
Hello World

The variable actually contains what it is supposed to now.

One of the cardinal rules of PowerShell is to not use Write-Host except in script that will be run interactively. .NET needs the results in the output stream not the host stream.

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