Octopus Deploy Post-Deploy script to update connectionString attributes within an ASP.Net web.config file

PostDeploy.ps1

# The following two lines were for debugging purposes to simulate the variables which are made available
# by Octopus when it invokes this script
#$OctopusParameters = @{}
#$OctopusParameters["DatabaseContext"] = "Data Source=DatabaseServer;Initial Catalog=Database;Integrated Security=true"

# This function is included because this function doesn't always seem to be available
# on freshly installed web servers when Octopus is deploying to. It is used to get the
# location where the script file is located, to allow the web.config file in the same
# location to be accessed.
function Get-ScriptDirectory {
    $invocation = (Get-Variable MyInvocation -Scope 1).Value
    $script = [IO.FileInfo] $invocation.MyCommand.Path
    if ([IO.File]::Exists($script)) {
        return (Split-Path $script.Fullname)
    } else {
        return $null
    }
}

$scriptDir = Get-ScriptDirectory

$webConfig = New-Object XML
$webConfig.Load("$scriptDir\web.config")
#$webConfig = (Get-Content "$scriptDir\web.config")
#$webConfig = [xml](Get-Content "$scriptDir\web.config")

# Iterate over each connection string within the web.config file
$webConfig.configuration.connectionStrings.add | ForEach-Object {

    # If the current connectionString name attribute is a valid key
    # within the variables hash table then update the connectionString 
    # attribute.
    if($OctopusParameters[$_.name] -ne $null){
        Write-Host $OctopusParameters[$_.name]
        $_.connectionString = $OctopusParameters[$_.name]
    }
    # This else is optional as within our scenario some connection strings are not
    # not required on some deployment servers, so if they are not listed within
    # Octopus' variables, the connectionString is deleted from web.config.
    else{
        #Connection string does not exist in OctopusParameters, delete from web.config
        $node = $_
        $node.ParentNode.RemoveChild($node)
    }

}

# Save the updated file from memory back to disk.
$webConfig.Save("$scriptDir\web.config")