fix: Use providerID from node obj instead of handcraft one (#173)

The node providerID has been updated by cloudprovider after node object
is created. We can always assume the vmID in vmss is 0. We should read
the providerID from the node object instead of handcrafting one with
hardcoded index of 0.

pkg/providers/instance/instance.go

@@ -146,16 +146,6 @@ func (p *Provider) Create(ctx context.Context, machine *v1alpha5.Machine) (*Inst
 	return instance, err
 }
 
-// getVMSSNodeProviderID generates the provider ID for a virtual machine scale set.
-func (p *Provider) getVMSSNodeProviderID(subscriptionID, scaleSetName string) string {
-	return fmt.Sprintf(
-		"/subscriptions/%s/resourceGroups/%s/providers/Microsoft.Compute/virtualMachineScaleSets/%s/virtualMachines/0", //vm = 0 as ew have the count always 1
-		subscriptionID,
-		strings.ToLower(p.nodeResourceGroup),
-		scaleSetName,
-	)
-}
-
 func (p *Provider) Get(ctx context.Context, id string) (*Instance, error) {
 	apName, err := utils.ParseAgentPoolNameFromID(id)
 	if err != nil {
@@ -196,11 +186,6 @@ func (p *Provider) Delete(ctx context.Context, id string) error {
 }
 
 func (p *Provider) fromAgentPoolToInstance(ctx context.Context, apObj *armcontainerservice.AgentPool) (*Instance, error) {
-	subID, err := utils.ParseSubIDFromID(lo.FromPtr(apObj.ID))
-	if err != nil {
-		return nil, err
-	}
-
 	node, err := p.getNodeByName(ctx, lo.FromPtr(apObj.Name))
 	if err != nil {
 		return nil, err
@@ -209,13 +194,12 @@ func (p *Provider) fromAgentPoolToInstance(ctx context.Context, apObj *armcontai
 		// node is not found or not ready
 		return nil, nil
 	}
-	tokens := strings.SplitAfter(node.Name, "-vmss") // remove the vm index "0000"
 	instanceLabels := lo.MapValues(apObj.Properties.NodeLabels, func(k *string, _ string) string {
 		return lo.FromPtr(k)
 	})
 	return &Instance{
 		Name:     apObj.Name,
-		ID:       to.Ptr(fmt.Sprint("azure://", p.getVMSSNodeProviderID(lo.FromPtr(subID), tokens[0]))),
+		ID:       to.Ptr(node.Spec.ProviderID),
 		Type:     apObj.Properties.VMSize,
 		SubnetID: apObj.Properties.VnetSubnetID,
 		Tags:     apObj.Properties.Tags,

pkg/providers/instance/instance_test.go

@@ -18,7 +18,6 @@ package instance
 import (
 	"context"
 	"errors"
-	"fmt"
 	"net/http"
 	"testing"
 
@@ -195,11 +194,6 @@ func TestFromAgentPoolToInstance(t *testing.T) {
 			},
 			expectedError: errors.New("Fail to get node list"),
 		},
-		{
-			name:          "Fail to get instance from agent pool due to malformed id",
-			mockAgentPool: tests.GetAgentPoolObjWithName("agentpool0", "/subscriptions/resourcegroups/nodeRG/providers/Microsoft.Compute/virtualMachineScaleSets/aks-agentpool0-20562481-vmss", "Standard_NC6s_v3"),
-			expectedError: errors.New("id does not match the regxp for ParseSubIDFromID"),
-		},
 	}
 
 	for _, tc := range testCases {
@@ -466,20 +460,6 @@ func TestFromAPListToInstanceFailure(t *testing.T) {
 				return errors.New("no agentpools found")
 			},
 		},
-		{
-			name: "Fail to get instance from agent pool list because agentpool subId can't be parsed",
-			id:   "/subscriptions/resourcegroups/nodeRG/providers/Microsoft.Compute/virtualMachineScaleSets/aks-agentpool0-20562481-vmss",
-			mockAgentPoolList: func(id string) []*armcontainerservice.AgentPool {
-				ap := tests.GetAgentPoolObjWithName("agentpool0", id, "Standard_NC6s_v3")
-
-				return []*armcontainerservice.AgentPool{
-					&ap,
-				}
-			},
-			expectedError: func(err string) error {
-				return fmt.Errorf("id does not match the regxp for ParseSubIDFromID %s", err)
-			},
-		},
 	}
 
 	for _, tc := range testCases {

pkg/tests/utils.go

@@ -83,6 +83,9 @@ var (
 				"kubernetes.azure.com/agentpool": "agentpool0",
 			},
 		},
+		Spec: v1.NodeSpec{
+			ProviderID: "azure:///subscriptions/00000000-0000-0000-0000-000000000000/resourceGroups/nodeRG/providers/Microsoft.Compute/virtualMachineScaleSets/aks-agentpool0-20562481-vmss/virtualMachines/0",
+		},
 		Status: v1.NodeStatus{
 			Conditions: []v1.NodeCondition{
 				{