Expands Azure Devops Variables

Expand-Variables.ps1

[CmdletBinding()]
param (
    [parameter(mandatory)][string]$EntryYamlPath
)
function Resolve-VariableTemplates {
    param (
        [string]$EntryYamlPath
    )

    $resolvedVariables = @{}

    function Resolve-YamlFile {
        param (
            [string]$YamlPath,
            [string]$BaseDirectory
        )

        $fullPath = if ([System.IO.Path]::IsPathRooted($YamlPath)) {
            $YamlPath
        } else {
            Join-Path -Path $BaseDirectory -ChildPath $YamlPath
        }

        if (-not (Test-Path $fullPath)) {
            throw "Template file not found: $fullPath"
        }

        $yamlContent = Get-Content $fullPath -Raw
        $parsed = ConvertFrom-Yaml $yamlContent

        $variables = $parsed.variables

        if ($variables -is [System.Collections.Generic.List[object]]) {
            foreach ($var in $variables) {
                if ($var.template) {
                    # Nested template
                    Resolve-YamlFile -YamlPath $var.template -BaseDirectory (Split-Path $fullPath)
                }
                elseif ($var.name) {
                    $resolvedVariables[$var.name] = $var.value
                }
            }
        }
        elseif ($variables -is [hashtable]) {
            foreach ($key in $variables.Keys) {
                $resolvedVariables[$key] = $variables[$key]
            }
        }
    }

    function Expand-Expressions {
        param (
            [hashtable]$variables
        )

        $expanded = @{}

        foreach ($key in $variables.Keys) {
            $value = $variables[$key]

            if ($value -is [string]) {
                # Look for ${{ ... }} patterns
                $value = [regex]::Replace($value, '\${{\s*(.*?)\s*}}', {
                    param($match)
                    $expression = $match.Groups[1].Value

                    if ($expression -like 'variables.*') {
                        $varName = $expression -replace '^variables\.', ''
                        return $variables[$varName]
                    } else {
                        return $match.Value  # Leave it unchanged
                    }
                })
            }

            $expanded[$key] = $value
        }

        return $expanded
    }

    Resolve-YamlFile -YamlPath $EntryYamlPath -BaseDirectory "."

    $expandedVariables = Expand-Expressions -variables $resolvedVariables

    return $expandedVariables
}

Resolve-VariableTemplates $EntryYamlPath