From b0cdc77f387c3616ff6b7bf0c92d5def17ddb926 Mon Sep 17 00:00:00 2001
From: Qi Ni <pomelonicky@gmail.com>
Date: Thu, 14 Oct 2021 10:11:23 +0800
Subject: [PATCH] fix: skip instance not found when decoupling vmss from lb

---
 .../azure/azure_vmss.go                       |  9 ++++++--
 .../azure/azure_vmss_test.go                  | 23 +++++++++++++++++--
 2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/staging/src/k8s.io/legacy-cloud-providers/azure/azure_vmss.go b/staging/src/k8s.io/legacy-cloud-providers/azure/azure_vmss.go
index 89ef88dc846..5ce18a0e8dd 100644
--- a/staging/src/k8s.io/legacy-cloud-providers/azure/azure_vmss.go
+++ b/staging/src/k8s.io/legacy-cloud-providers/azure/azure_vmss.go
@@ -1492,11 +1492,11 @@ func (ss *scaleSet) ensureBackendPoolDeletedFromVMSS(service *v1.Service, backen
 		// When vmss is being deleted, CreateOrUpdate API would report "the vmss is being deleted" error.
 		// Since it is being deleted, we shouldn't send more CreateOrUpdate requests for it.
 		if vmss.ProvisioningState != nil && strings.EqualFold(*vmss.ProvisioningState, virtualMachineScaleSetsDeallocating) {
-			klog.V(3).Infof("ensureVMSSInPool: found vmss %s being deleted, skipping", vmssName)
+			klog.V(3).Infof("ensureBackendPoolDeletedFromVMSS: found vmss %s being deleted, skipping", vmssName)
 			continue
 		}
 		if vmss.VirtualMachineProfile.NetworkProfile.NetworkInterfaceConfigurations == nil {
-			klog.V(4).Infof("EnsureHostInPool: cannot obtain the primary network interface configuration, of vmss %s", vmssName)
+			klog.V(4).Infof("ensureBackendPoolDeletedFromVMSS: cannot obtain the primary network interface configuration, of vmss %s", vmssName)
 			continue
 		}
 		vmssNIC := *vmss.VirtualMachineProfile.NetworkProfile.NetworkInterfaceConfigurations
@@ -1615,6 +1615,11 @@ func (ss *scaleSet) EnsureBackendPoolDeleted(service *v1.Service, backendPoolID,
 				continue
 			}
 
+			if errors.Is(err, cloudprovider.InstanceNotFound) {
+				klog.Infof("EnsureBackendPoolDeleted(%s): skipping ip config %s because the corresponding vmss vm is not found", getServiceName(service), ipConfigurationID)
+				continue
+			}
+
 			klog.Errorf("Failed to GetNodeNameByIPConfigurationID(%s): %v", ipConfigurationID, err)
 			allErrs = append(allErrs, err)
 			continue
diff --git a/staging/src/k8s.io/legacy-cloud-providers/azure/azure_vmss_test.go b/staging/src/k8s.io/legacy-cloud-providers/azure/azure_vmss_test.go
index a756cc52eea..97239bcbf4f 100644
--- a/staging/src/k8s.io/legacy-cloud-providers/azure/azure_vmss_test.go
+++ b/staging/src/k8s.io/legacy-cloud-providers/azure/azure_vmss_test.go
@@ -2433,6 +2433,26 @@ func TestEnsureBackendPoolDeleted(t *testing.T) {
 			expectedErr:            true,
 			vmClientErr:            &retry.Error{RawError: fmt.Errorf("error")},
 		},
+		{
+			description:   "EnsureBackendPoolDeleted should skip the node that doesn't exist",
+			backendpoolID: testLBBackendpoolID0,
+			backendAddressPools: &[]network.BackendAddressPool{
+				{
+					ID: to.StringPtr(testLBBackendpoolID0),
+					BackendAddressPoolPropertiesFormat: &network.BackendAddressPoolPropertiesFormat{
+						BackendIPConfigurations: &[]network.InterfaceIPConfiguration{
+							{
+								Name: to.StringPtr("ip-1"),
+								ID:   to.StringPtr("/subscriptions/sub/resourceGroups/rg/providers/Microsoft.Compute/virtualMachineScaleSets/vmss/virtualMachines/6/networkInterfaces/nic"),
+							},
+						},
+					},
+				},
+				{
+					ID: to.StringPtr(testLBBackendpoolID1),
+				},
+			},
+		},
 	}
 
 	for _, test := range testCases {
@@ -2487,7 +2507,6 @@ func TestEnsureBackendPoolDeletedConcurrently(t *testing.T) {
 			},
 		},
 		{
-			// this would fail
 			ID: to.StringPtr(testLBBackendpoolID2),
 			BackendAddressPoolPropertiesFormat: &network.BackendAddressPoolPropertiesFormat{
 				BackendIPConfigurations: &[]network.InterfaceIPConfiguration{
@@ -2526,7 +2545,7 @@ func TestEnsureBackendPoolDeletedConcurrently(t *testing.T) {
 	mockVMSSVMClient.EXPECT().UpdateVMs(gomock.Any(), ss.ResourceGroup, gomock.Any(), gomock.Any(), gomock.Any()).Return(nil).Times(2)
 
 	backendpoolAddressIDs := []string{testLBBackendpoolID0, testLBBackendpoolID1, testLBBackendpoolID2}
-	testVMSSNames := []string{"vmss-0", "vmss-1", "vmss-0"}
+	testVMSSNames := []string{"vmss-0", "vmss-1", "vmss-2"}
 	testFunc := make([]func() error, 0)
 	for i, id := range backendpoolAddressIDs {
 		i := i