Search and Replace in Powershell

In scenarios where we keep configuration information in app.config or web.config files (or .cscfg’s even), there is often a need to replace non-secret dev settings for local machines with settings referencing protected resources, for example, production database credentials.

This little script is aimed at a quick and dirty solution to that problem, replacing the placeholder keys in the hash with the “production” values. Of course, for a production system the actual settings could be imported from a file as a command line param rather than being hard-coded.


Function Replace-ConfigSecrets {
	[CmdletBinding()]
	Param (
		[string]$ConfigPath
	) 

$Replacements = @{

    '##MY_CREDENTIALS_USERNAME##' = 'This is not my user name' 
    '##MY_CREDENTIALS_PASSWORD##' = 'This might be my password'
}

Write-Verbose "Starting to process $ConfigPath"

(Get-Content -Path $ConfigPath) | ForEach-Object { 
    
	$EachLine = $_

    $Replacements.GetEnumerator() | ForEach-Object {
		
        if ($EachLine -match $_.Key)
        {
            Write-Verbose "Changing $EachLine to $($_.Value)" 
            $EachLine = $EachLine -replace $($_.Key), $($_.Value)

            Write-Verbose "Line is now $EachLine"
        }
   }

    $EachLine
} | Out-File $ConfigPath

Write-Verbose "Completed processing for $ConfigPath"