vsts-update-transformation-file.ps1

# This script saves an XD transform file into MS Deploy Package with additional validations

# FOR MORE INFO ABOUT XDT TRANSFORMS READ HERE 
# https://msdn.microsoft.com/en-us/library/dd465326(v=vs.110).aspx

[CmdletBinding()]
Param(
    <#
        .SYNOPSIS Path to the file contents of which should be added to the package, contents of this file is the XD transform
    #>
    [Parameter(Mandatory=$true)]
    [ValidateScript({Test-Path $_})]
    [ValidateNotNullOrEmpty()]
    [string]$filePath,

    <#
        .SYNOPSIS Transform target file name, to determine location of the transform file in the package (e.g. Web.config)
    #>
    [Parameter(Mandatory=$true)]
    [ValidateNotNullOrEmpty()]
    [string]$transformTargetFileName,

    <#
        .SYNOPSIS Transform file name, to determine if it already exists (e.g. Web.Release.config)
    #>
    [Parameter(Mandatory=$true)]
    [ValidateNotNullOrEmpty()]
    [string]$transformFileName,

    <#
        .SYNOPSIS Defines whether to overwrite the existing transform file if it exists
    #>
    [Parameter(Mandatory=$false)]
    [ValidateNotNullOrEmpty()]
    [bool]$overwrite = $false,

    <#
        .SYNOPSIS Target directory to look for the deploy package
    #>
    [Parameter(Mandatory=$false)]
    [ValidateScript({Test-Path $_})]
    [ValidateNotNullOrEmpty()]
    [string]$targetDir = ".",

    <#
        .SYNOPSIS Package file name
    #>
    [Parameter(Mandatory=$false)]
    [ValidateNotNullOrEmpty()]
    [string]$zipFileName = "*.zip"
)

$transformContents = (Get-Content $filePath) -join "`r`n"
$overwriteTransformFile = $overwrite

# Path to the MS Deploy ZIP package with web site contents
$zipPath = (Get-ChildItem -Path "$targetDir\**\$zipFileName" -Recurse).FullName
if (!($zipPath)) {
    throw "MS Deploy Package not found"
}
if (($zipPath -is [system.array]) -and $zipPath.Length -gt 1) {
    throw "Multiple packages found at: " + $zipPath
}


# Location of the transformation target in the the zip package
# NOTE: PackageTmp corresponds to the root directory for our web site which has complicated base directory path, hence the `.*` regex
$transformTargetLocator = ".*/PackageTmp/$([regex]::Escape($transformTargetFileName))".Replace("/", "(/|\\)")
$transformLocator = ".*/PackageTmp/$([regex]::Escape($transformFileName))".Replace("/", "(/|\\)")

# Open zip and find the transformation target
Add-Type -assembly  System.IO.Compression.FileSystem
$zip =  [System.IO.Compression.ZipFile]::Open($zipPath, "Update")
try {
    $transformLocation = ($zip.Entries | Where-Object { $_.FullName -match $transformLocator }).FullName
    $transformTargetLocation = ($zip.Entries | Where-Object { $_.FullName -match $transformTargetLocator }).FullName
    
    if (!($transformTargetLocation)) {
        Write-Warning "XDT Transform target at '$transformTargetLocator' not found, skipping transform file generation"
        return
    }

    if ($transformLocation -and (-not $overwriteTransformFile)) {
        throw "Transform file at '$transformLocation' already exists, either change the transform file name, ensure that it doesn't exist, " + 
            "set `$overwriteTransformFile to `$true or disable this VSTS step"
    }

    $transformParentDirectory = [System.IO.Path]::GetDirectoryName($transformTargetLocation).Replace("\", "/")
    $transformFilePath = $transformParentDirectory + "/$transformFileName"

    $action = ""
    $transformFile = if ($transformLocation) {
        $action = "existing file"
        $zip.GetEntry($transformLocation)
    } else {
        $action = "new file"
        $zip.CreateEntry($transformFilePath)
    }
    
    # Update the contents of the transform file
    $newTransformFile = [System.IO.StreamWriter]($transformFile).Open()
    try {
        $newTransformFile.BaseStream.SetLength(0)
        $newTransformFile.Write($transformContents)
        $newTransformFile.Flush()
    } finally {
        $newTransformFile.Close()
    }

    $reader = [System.IO.StreamReader]($transformFile).Open()
    try {
        $transformContents = $reader.ReadToEnd()
    } finally {
        $reader.Close()
    }

    Write-Host "Zip file '$zipPath' updated with $action '$transformFileName' at '$transformParentDirectory' now having following contents:"
    Write-Output $transformContents
} finally {
    $zip.Dispose()
}