DevAzure Release Pipeline NetCore Web.Config Transform Step for Environment Variables Substitution

DevAzureReleaseNetCoreWebConfigTransformStep.ps1

# Populate Web.config EnvironmentVariables from Pipeline variables
#
# Usage: Copy-paste this script into a Powershell Task, as an inline script, in your release pipeline.
#
# -----------------------------------------------------
# Known Variables: 
# DOTNET_ENVIRONMENT
# TraceTransforms
# -----------------------------------------------------
# Editing this script: 
# Make sure you know both pipeline variable substitution and 
# powershell variable substitution and, when to escape `$`()

$script:zipfile= ( gci "$(Release.PrimaryArtifactSourceAlias)\*.zip" -recurse | Select -First 1 )
$script:tempwebconfig = "$(Agent.TempDirectory)\web.config"

function ShowDebuggingInformation(){
    "—————————————"
    gci "$(Release.PrimaryArtifactSourceAlias)\*.zip" -recurse
    "—————————————"        
    "zipfile: $($zipfile.FullName)"
    $zipfile
    "tempwebconfig: $tempwebconfig"
    "—————————————"
    "Transforming:
    `$`(DOTNET_ENVIRONMENT) = $(DOTNET_ENVIRONMENT)
    `$`(TraceTransforms) = $(TraceTransforms)
    —————————————"
}
function TransformWebConfig(){

    Get-ZippedContent $zipfile web.config | 
        %{ $_.Replace( "`$`(DOTNET_ENVIRONMENT)", "$(DOTNET_ENVIRONMENT)" ) } | 
        %{ $_.Replace( "`$`(TraceTransforms)", "$(TraceTransforms)" ) } | 
        Out-File $tempwebconfig -Encoding ASCII

    Compress-Archive "$tempwebconfig" -DestinationPath ($zipfile.FullName) -Update

    "—————————————"
    Get-Content $tempwebconfig
    "—————————————"
}

Add-Type -AssemblyName System.IO.Compression.FileSystem

function Get-ZippedContent{
  [OutputType([String])]
  [CmdletBinding()]
  Param( $ZipFilePath, $FilePathInZip)

  $verbose = $VerbosePreference -ne 'SilentlyContinue'
  if (-not (test-path $ZipFilePath)) {
    throw "Zip file ""$ZipFilePath"" not found."
  }
  try {
    $Zip = [System.IO.Compression.ZipFile]::OpenRead( (Resolve-Path $ZipFilePath) )
    write-verbose "Opened $ZipFilePath : $(($zz.Entries | measure).Count) entries"
    $matchingEntries= $Zip.Entries | where-object {return $_.FullName -like $FilePathInZip}
    write-verbose "$(($matchingEntries | measure).Count) entries match ""$FilePathInZip"""

    $matchingEntries |
      ForEach-object {
        write-verbose "Found $($_.FullName)"
        $ZipStream = $_.Open()
        try{
          $Reader = [System.IO.StreamReader]::new($ZipStream)          
          $s= $Reader.ReadToEnd()
          write-verbose "Length $($s.Length)"
          $s
        }
        finally{ 
          if($Reader){$Reader.Dispose()}
        }
      }
  }
  finally {if ($Zip) { $Zip.Dispose() } }
}

#And now, run the script

ShowDebuggingInformation
TransformWebConfig

This script will

1. Extract a web.config from an AspNetCore published website in a zipfile found anywhere in the default (Release.PrimaryArtifactSourceAlias) location
2. Transform it by replacing occurences of $(DOTNET_ENVIRONMENT) with the current defined value of the variable DOTNET_ENVIRONMENT in your release stage