better error

Author: timmy-wright

staging/cse/windows/kubernetesfunc.ps1

@@ -182,6 +182,7 @@ function Check-APIServerConnectivity {
     )
     Logs-To-Event -TaskName "AKS.WindowsCSE.CheckAPIServerConnectivity" -TaskMessage "Start to check API server connectivity."
     $retryCount=0
+    $LastException=$null
 
     do {
         $retryString="${retryCount}/${MaxRetryCount}"
@@ -202,16 +203,18 @@ function Check-APIServerConnectivity {
             $tcpClient.Close()
         } catch [System.AggregateException] {
             Write-Log "Retry ${retryString}: Failed to connect to API server $MasterIP. AggregateException: " + $_.Exception.ToString()
+            $LastException = $_.Exception.ToString()
         } catch {
             Write-Log "Retry ${retryString}: Failed to connect to API server $MasterIP. Error: $_"
-        }
+            $LastException = $_.ToString()
+      }
 
         $retryCount++
         Write-Log "Retry ${retryString}: Sleep $RetryInterval and then retry to connect to API server"
         Sleep $RetryInterval
     } while ($retryCount -lt $MaxRetryCount)
 
-    Set-ExitCode -ExitCode $global:WINDOWS_CSE_ERROR_CHECK_API_SERVER_CONNECTIVITY -ErrorMessage "Failed to connect to API server $MasterIP after $retryCount retries"
+    Set-ExitCode -ExitCode $global:WINDOWS_CSE_ERROR_CHECK_API_SERVER_CONNECTIVITY -ErrorMessage "Failed to connect to API server $MasterIP after $retryCount retries. Last exception: $LastException"
 }
 
 function Get-CACertificates {