allow validation to pass when subnet filters are present

builder/amazon/common/step_pre_validate.go

@@ -23,6 +23,7 @@ type StepPreValidate struct {
 	AMISkipBuildRegion bool
 	VpcId              string
 	SubnetId           string
+	HasSubnetFilter    bool
 }
 
 func (s *StepPreValidate) Run(ctx context.Context, state multistep.StateBag) multistep.StepAction {
@@ -121,10 +122,11 @@ func (s *StepPreValidate) Run(ctx context.Context, state multistep.StateBag) mul
 }
 
 func (s *StepPreValidate) checkVpc(conn ec2iface.EC2API) error {
-	if s.VpcId == "" || (s.VpcId != "" && s.SubnetId != "") {
+	if s.VpcId == "" || (s.VpcId != "" && (s.SubnetId != "" || s.HasSubnetFilter)) {
 		// Skip validation if:
 		// * The user has not provided a VpcId.
 		// * Both VpcId and SubnetId are provided; AWS API will error if something is wrong.
+		// * Both VpcId and SubnetFilter are provided
 		return nil
 	}
 
@@ -135,7 +137,7 @@ func (s *StepPreValidate) checkVpc(conn ec2iface.EC2API) error {
 
 	if res != nil && len(res.Vpcs) == 1 && res.Vpcs[0] != nil {
 		if isDefault := aws.BoolValue(res.Vpcs[0].IsDefault); !isDefault {
-			return fmt.Errorf("Error: subnet_id must be provided for non-default VPCs (%s)", s.VpcId)
+			return fmt.Errorf("Error: subnet_id or subnet_filter must be provided for non-default VPCs (%s)", s.VpcId)
 		}
 	}
 	return nil

builder/amazon/common/step_pre_validate_test.go

@@ -45,6 +45,7 @@ func TestStepPreValidate_checkVpc(t *testing.T) {
 		{"NonDefaultVpcWithSubnet", StepPreValidate{VpcId: "vpc-1234567890", SubnetId: "subnet-1234567890"}, false},
 		{"SubnetWithNoVpc", StepPreValidate{SubnetId: "subnet-1234567890"}, false},
 		{"NoVpcInformation", StepPreValidate{}, false},
+		{"NonDefaultVpcWithSubnetFilter", StepPreValidate{VpcId: "vpc-1234567890", HasSubnetFilter: true}, false},
 	}
 
 	mockConn, err := getMockConn(nil, "")

builder/amazon/ebs/builder.go

@@ -209,6 +209,7 @@ func (b *Builder) Run(ctx context.Context, ui packer.Ui, hook packer.Hook) (pack
 			AMISkipBuildRegion: b.config.AMISkipBuildRegion,
 			VpcId:              b.config.VpcId,
 			SubnetId:           b.config.SubnetId,
+			HasSubnetFilter:    len(b.config.SubnetFilter.Filters) > 0,
 		},
 		&awscommon.StepSourceAMIInfo{
 			SourceAmi:                b.config.SourceAmi,

builder/amazon/ebssurrogate/builder.go

@@ -232,6 +232,7 @@ func (b *Builder) Run(ctx context.Context, ui packer.Ui, hook packer.Hook) (pack
 			ForceDeregister: b.config.AMIForceDeregister,
 			VpcId:           b.config.VpcId,
 			SubnetId:        b.config.SubnetId,
+			HasSubnetFilter: len(b.config.SubnetFilter.Filters) > 0,
 		},
 		&awscommon.StepSourceAMIInfo{
 			SourceAmi:                b.config.SourceAmi,

builder/amazon/instance/builder.go

@@ -294,6 +294,7 @@ func (b *Builder) Run(ctx context.Context, ui packer.Ui, hook packer.Hook) (pack
 			ForceDeregister: b.config.AMIForceDeregister,
 			VpcId:           b.config.VpcId,
 			SubnetId:        b.config.SubnetId,
+			HasSubnetFilter: len(b.config.SubnetFilter.Filters) > 0,
 		},
 		&awscommon.StepSourceAMIInfo{
 			SourceAmi:                b.config.SourceAmi,