Merge pull request #3978 from giantswarm/machinepool_subnet_filters

Fail creation of machine pool if no subnets matching filters found

Author: k8s-ci-robot

pkg/cloud/services/autoscaling/autoscalinggroup.go

@@ -526,6 +526,12 @@ func (s *Service) SubnetIDs(scope *scope.MachinePoolScope) ([]string, error) {
 		for _, subnet := range out.Subnets {
 			subnetIDs = append(subnetIDs, *subnet.SubnetId)
 		}
+
+		if len(subnetIDs) == 0 {
+			errMessage := fmt.Sprintf("failed to create ASG %q, no subnets available matching criteria %q", scope.Name(), inputFilters)
+			record.Warnf(scope.AWSMachinePool, "FailedCreate", errMessage)
+			return subnetIDs, awserrors.NewFailedDependency(errMessage)
+		}
 	}
 
 	return scope.SubnetIDs(subnetIDs)

pkg/cloud/services/autoscaling/autoscalinggroup_test.go

@@ -643,6 +643,26 @@ func TestServiceUpdateASGWithSubnetFilters(t *testing.T) {
 				m.UpdateAutoScalingGroup(gomock.AssignableToTypeOf(&autoscaling.UpdateAutoScalingGroupInput{})).Return(&autoscaling.UpdateAutoScalingGroupOutput{}, nil)
 			},
 		},
+		{
+			name:            "should return an error if no matching subnets found",
+			machinePoolName: "update-asg-fail",
+			wantErr:         true,
+			awsResourceReference: []infrav1.AWSResourceReference{
+				{
+					Filters: []infrav1.Filter{
+						{
+							Name:   "tag:subnet-role",
+							Values: []string{"non-existent"},
+						},
+					},
+				},
+			},
+			expect: func(e *mocks.MockEC2APIMockRecorder, m *mock_autoscalingiface.MockAutoScalingAPIMockRecorder) {
+				e.DescribeSubnets(gomock.AssignableToTypeOf(&ec2.DescribeSubnetsInput{})).Return(&ec2.DescribeSubnetsOutput{
+					Subnets: []*ec2.Subnet{},
+				}, nil)
+			},
+		},
 		{
 			name:            "should return error if update ASG fails",
 			machinePoolName: "update-asg-fail",