Merge pull request #3519 from marwanad/cherry-pick-3484-1.18

Cherry pick #3484 onto 1.18: Serve stale on ongoing throttling

cluster-autoscaler/cloudprovider/azure/azure_util.go

@@ -664,12 +664,17 @@ func convertResourceGroupNameToLower(resourceID string) (string, error) {
 	return strings.Replace(resourceID, resourceGroup, strings.ToLower(resourceGroup), 1), nil
 }
 
-// isAzureRequestsThrottled returns true when the err is http.StatusTooManyRequests (429).
+// isAzureRequestsThrottled returns true when the err is http.StatusTooManyRequests (429),
+// and when err shows the requests was not executed due to an ongoing throttling period.
 func isAzureRequestsThrottled(rerr *retry.Error) bool {
 	klog.V(6).Infof("isAzureRequestsThrottled: starts for error %v", rerr)
 	if rerr == nil {
 		return false
 	}
 
+	if rerr.HTTPStatusCode == 0 && rerr.RetryAfter.After(time.Now()) {
+		return true
+	}
+
 	return rerr.HTTPStatusCode == http.StatusTooManyRequests
 }

cluster-autoscaler/cloudprovider/azure/azure_util_test.go

@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"net/http"
 	"testing"
+	"time"
 
 	"github.com/Azure/azure-sdk-for-go/services/compute/mgmt/2019-07-01/compute"
 	"github.com/stretchr/testify/assert"
@@ -270,6 +271,13 @@ func TestIsAzureRequestsThrottled(t *testing.T) {
 			},
 			expected: true,
 		},
+		{
+			desc: "Nul HTTP code and non-expired Retry-After should return true",
+			rerr: &retry.Error{
+				RetryAfter: time.Now().Add(time.Hour),
+			},
+			expected: true,
+		},
 	}
 
 	for _, test := range tests {