Replacing dynamic variables using REGEX content as variable in Azure CD Pipeline Powershell Task

Question

I'm writing custom Powershell Azure CD Pipeline task(for VM) where my web.config should be replaced with pipeline variables. I have sample config file as with WebService and AuditService defined in my Azure CD pipeline variables.

<client>
      <endpoint address="__WebService__" binding="basicHttpBinding" bindingConfiguration="ServiceSoap" contract="WebServiceClient.ServiceSoap" name="NLSService" />
      <endpoint address="__AuditService__" binding="basicHttpBinding" bindingConfiguration="BasicHttpBinding_Audit" contract="AuditApiService.Audit" name="AuditService" />
    </client>

I have powershell script as

$zipfileName = "$(System.DefaultWorkingDirectory)\_WebService-CI\drop\Service.zip"
$fileToEdit = "web.config"
$reg = [regex] '__(.*?)__'


[Reflection.Assembly]::LoadWithPartialName("System.IO.Compression.FileSystem");
# Open zip and find the particular file (assumes only one inside the Zip file)
$zip =  [System.IO.Compression.ZipFile]::Open($zipfileName,"Update")
$configFile = $zip.Entries.Where({$_.name -like $fileToEdit})

# Read the contents of the file
$desiredFile = [System.IO.StreamReader]($configFile).Open()
$text = $desiredFile.ReadToEnd()
$desiredFile.Close()
$desiredFile.Dispose()


$text = $text -replace $reg, $(${1}) -join "`r`n"
    #update file with new content
$desiredFile = [System.IO.StreamWriter]($configFile).Open()
$desiredFile.BaseStream.SetLength(0)

# Insert the $text to the file and close
$desiredFile.Write($text)
$desiredFile.Flush()
$desiredFile.Close()

# Write the changes and close the zip file
$zip.Dispose()

So how do I can replace dynamically Regex content within "__" and treat that content as a variable which should look into pipeline variables and replace it in line :

$text = $text -replace $reg, $(${1}) -join "rn"

Heed the other answer. It very likely is a better approach. If you choose to stay on this one look at stackoverflow.com/questions/30666101/… which you can incorporate with a hashtable of replacements that would work here just fine. — Matt

JPBlanc JPBlanc · Accepted Answer · 2020-04-28T06:22:44

If you can't use Replace Tokens or Transform Web.config file, here is something :

According to the fact that web.config file contains :

<?xml version="1.0" encoding="utf-8"?>
<!--
  For ...
  -->
<configuration>
..
  <system.serviceModel>
    <bindings>
      <basicHttpBinding>
        <binding name="checkVatBinding" />
      </basicHttpBinding>
    </bindings>
    <client>
      <endpoint address="__WebService__" binding="basicHttpBinding" bindingConfiguration="ServiceSoap" contract="WebServiceClient.ServiceSoap" name="NLSService" />
      <endpoint address="__AuditService__" binding="basicHttpBinding" bindingConfiguration="BasicHttpBinding_Audit" contract="AuditApiService.Audit" name="AuditService" />
    </client>
  </system.serviceModel>
</configuration>

You can try the following :

# Get all the file in a single var in spite of an array    
$data = Get-Content "D:\temp\web.config" -raw
$reg = [Regex]::new( '__(.*?)__', [System.Text.RegularExpressions.RegexOptions]::Singleline)
# Here are the vars with the final values
$WebService = "http://Aurillac.fr"
$AuditService = "http://Cantal.fr"
# Here is how to replace
$reg.replace($data, {param ($p);return (Get-Variable -Name $p.groups[1]).Value})

Explanations :

The -raw in Get-Content allows to get all the characters in a single string
I use the .NET RegEx class with the option Singleline to allow search accross cariage return line feed (perhaps not necessary)
I use the Regex Replace method with a MatchEvaluator Delegate method translated in PowerShell by a Scriptblock to get the variable with the name catched by the RegEx.

It gives :

<?xml version="1.0" encoding="utf-8"?>
<!--
  For ...
  -->
<configuration>
..
  <system.serviceModel>
    <bindings>
      <basicHttpBinding>
        <binding name="checkVatBinding" />
      </basicHttpBinding>
    </bindings>
    <client>
      <endpoint address="http://Aurillac.fr" binding="basicHttpBinding" bindingConfiguration="ServiceSoap" contract="WebServiceClient.ServiceSoap" name="NLSService" />
      <endpoint address="http://Cantal.fr" binding="basicHttpBinding" bindingConfiguration="BasicHttpBinding_Audit" contract="AuditApiService.Audit" name="AuditService" />
    </client>
  </system.serviceModel>
</configuration>

Replacing dynamic variables using REGEX content as variable in Azure CD Pipeline Powershell Task

2 Answers