fix(ingress): count against chosen subnets

Author: swarner1033

pkg/ingress/model_build_frontend_nlb.go

@@ -130,9 +130,6 @@ func (t *defaultModelBuildTask) buildFrontendNlbSubnetMappings(ctx context.Conte
 				return nil, errors.Errorf("all EIP allocations for the ingress group must be the same: %v | %v", chosenEipAllocations, eipAllocations)
 			}
 		}
-		if len(eipAllocationsList) != len(explicitSubnetNameOrIDsList) {
-			return nil, errors.Errorf("count of EIP allocations (%d) and subnets (%d) must match", len(eipAllocationsList), len(explicitSubnetNameOrIDsList))
-		}
 	}
 
 	if len(explicitSubnetNameOrIDsList) != 0 {
@@ -150,15 +147,18 @@ func (t *defaultModelBuildTask) buildFrontendNlbSubnetMappings(ctx context.Conte
 			return nil, err
 		}
 
+		if len(chosenEipAllocations) != len(chosenSubnets) {
+			return nil, errors.Errorf("count of EIP allocations (%d) and subnets (%d) must match", len(chosenEipAllocations), len(explicitSubnetNameOrIDsList))
+		}
+
 		return buildFrontendNlbSubnetMappingsWithSubnets(chosenSubnets, chosenEipAllocations), nil
 	}
 
-
 	return nil, nil
 
 }
 
-// I found a bug in the current implementation where EIP allocations require both subnets AND EIPs to be provided together, but there's an indexing issue in buildFrontendNlbSubnetMappingsWithSubnets. 
+// I found a bug in the current implementation where EIP allocations require both subnets AND EIPs to be provided together, but there's an indexing issue in buildFrontendNlbSubnetMappingsWithSubnets.
 // The function tries to access eipAllocation[subnetIndex][0] but the data structure is eipAllocation[ingressIndex][eipIndex].
 func buildFrontendNlbSubnetMappingsWithSubnets(subnets []ec2types.Subnet, eipAllocation []string) []elbv2model.SubnetMapping {
 	subnetMappings := make([]elbv2model.SubnetMapping, 0, len(subnets))

pkg/ingress/model_build_frontend_nlb_test.go

@@ -244,6 +244,36 @@ func Test_buildFrontendNlbSubnetMappings(t *testing.T) {
 				{SubnetID: "subnet-2", AllocationID: nil},
 			},
 		},
+		{
+			name: "with subnets and eip allocations",
+			fields: fields{
+				ingGroup: Group{
+					ID: GroupID{
+						Namespace: "awesome-ns",
+						Name:      "my-ingress",
+					},
+					Members: []ClassifiedIngress{
+						{
+							Ing: &networking.Ingress{
+								ObjectMeta: metav1.ObjectMeta{
+									Namespace: "awesome-ns",
+									Name:      "ing-3",
+									Annotations: map[string]string{
+										"alb.ingress.kubernetes.io/frontend-nlb-subnets":         "subnet-1,subnet-2",
+										"alb.ingress.kubernetes.io/frontend-nlb-eip-allocations": "eip-1,eip-2",
+									},
+								},
+							},
+						},
+					},
+				},
+				scheme: elbv2.LoadBalancerSchemeInternetFacing, // EIPs require internet-facing
+			},
+			wantMappings: []expectedMapping{
+				{SubnetID: "subnet-1", AllocationID: awssdk.String("eip-1")},
+				{SubnetID: "subnet-2", AllocationID: awssdk.String("eip-2")},
+			},
+		},
 	}
 
 	for _, tt := range tests {