A powershell script to inject environmentVariable elements into aspNetCore Element in web.config for ASP.NET Core Module

Add-AspNetCoreEnvVarElems.ps1

#
# == Turn This ==
# <?xml version="1.0" encoding="utf-8"?>
# <configuration>
# <system.webServer>
#   <handlers>
#     <add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModule" resourceType="Unspecified" />
#   </handlers>
#   <aspNetCore processPath=".\MyCoreGizmo.exe" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout" />
# </system.webServer>
# </configuration>
#
# == Into This ==
#
# <?xml version="1.0" encoding="utf-8"?>
# <configuration>
# <system.webServer>
#   <handlers>
#     <add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModule" resourceType="Unspecified" />
#   </handlers>
#   <aspNetCore processPath=".\MyCoreGizmo.exe" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout">
#     <environmentVariables>
#       <environmentVariable name="ASPNETCORE_ENVIRONMENT" value="Development" />
#     </environmentVariables>
#   </aspNetCore>
# </system.webServer>
# </configuration>

param(
    [string] $WebConfigPath = ".\web.config",
    [string] $EnvironmentName = "Development"
)

$WebConfigXml = [xml](Get-Content $WebConfigPath -Encoding "UTF8")

$EVarsParent = $WebConfigXml.CreateElement("environmentVariables")
$EVarChild = $WebConfigXml.CreateElement("environmentVariable")
$EVarChild.SetAttribute("name", "ASPNETCORE_ENVIRONMENT")
$EVarChild.SetAttribute("value", $EnvironmentName)

$EVarsParent.AppendChild($EVarChild) | Out-Null

$AspNetCoreNode = $WebConfigXml.SelectSingleNode("/configuration/system.webServer/aspNetCore")
$AspNetCoreNode.AppendChild($EVarsParent) | Out-Null

# How to keep 'pretty print' formatting is a conundrum
$PrettyXml = $WebConfigXml.Save([Console]::Out) # This converts encoding='utf-8' to encoding='IBM437'
Write-Output $PrettyXml

# This loses indentation and line breaks, but preserves the xml encoding
Set-Content -Path $WebConfigPath -Value $WebConfigXml.OuterXml -Encoding "UTF8"