Powershell Anonymous Lamda for Retry with Exponential Backoff

gistfile1.txt

# https://vexx32.github.io/2018/10/26/Anonymous-Functions/

function Retry()
{
    param(
        [Parameter(Mandatory=$true)][Action]$action,
        [Parameter(Mandatory=$false)][int]$maxAttempts = 3
    )

    $attempts=1    
    $ErrorActionPreferenceToRestore = $ErrorActionPreference
    $ErrorActionPreference = "Stop"

    do
    {
        try
        {
            $action.Invoke();
            break;
        }
        catch [Exception]
        {
            Write-Host $_.Exception.Message
        }

        # exponential backoff delay
        $attempts++
        if ($attempts -le $maxAttempts) 
        {
            $retryDelaySeconds = [math]::Pow(2, $attempts)
            $retryDelaySeconds = $retryDelaySeconds - 1  # Exponential Backoff Max == (2^n)-1
            Write-Host("Action failed. Waiting " + $retryDelaySeconds + " seconds before attempt " + $attempts + " of " + $maxAttempts + ".")
            Start-Sleep -Milliseconds $retryDelaySeconds            
        }
        else 
        {
            $ErrorActionPreference = $ErrorActionPreferenceToRestore
            Write-Error $_.Exception.Message
        }
    } while ($attempts -le $maxAttempts)

    $ErrorActionPreference = $ErrorActionPreferenceToRestore
}

function MyFunction($inputArg)
{
    Throw $inputArg
}

# #Example of a call:
 Retry({MyFunction "Oh no! It happened again!"})
 Retry {MyFunction "Oh no! It happened again!"} -maxAttempts 10