Add middleware

pkg/driftctl.go

@@ -38,6 +38,7 @@ func (d DriftCTL) Run() *analyser.Analysis {
 		middlewares.NewVPCSecurityGroupRuleSanitizer(),
 		middlewares.NewIamPolicyAttachmentSanitizer(),
 		middlewares.AwsInstanceEIP{},
+		middlewares.NewAwsDefaultInternetGatewayRoute(),
 		middlewares.NewAwsDefaultInternetGateway(),
 		middlewares.NewAwsDefaultVPC(),
 		middlewares.NewAwsDefaultSubnet(),

pkg/middlewares/aws_default_igw_route.go

@@ -0,0 +1,72 @@
+package middlewares
+
+import (
+	"github.com/cloudskiff/driftctl/pkg/resource"
+	"github.com/cloudskiff/driftctl/pkg/resource/aws"
+	"github.com/sirupsen/logrus"
+)
+
+// Each region has a default vpc which has an internet gateway attached and thus the route table of this
+// same vpc has a specific default route that should not be seen as unmanaged if not managed by IaC
+// This middleware ignores the above route from unmanaged resources if not managed by IaC
+type AwsDefaultInternetGatewayRoute struct{}
+
+func NewAwsDefaultInternetGatewayRoute() AwsDefaultInternetGatewayRoute {
+	return AwsDefaultInternetGatewayRoute{}
+}
+
+func (m AwsDefaultInternetGatewayRoute) Execute(remoteResources, resourcesFromState *[]resource.Resource) error {
+	newRemoteResources := make([]resource.Resource, 0)
+
+	for _, remoteResource := range *remoteResources {
+		// Ignore all resources other than routes
+		if remoteResource.TerraformType() != aws.AwsRouteResourceType {
+			newRemoteResources = append(newRemoteResources, remoteResource)
+			continue
+		}
+
+		route, _ := remoteResource.(*aws.AwsRoute)
+		// Ignore all routes except the one that came from the default internet gateway
+		if !isDefaultInternetGatewayRoute(route, remoteResources) {
+			newRemoteResources = append(newRemoteResources, remoteResource)
+			continue
+		}
+
+		// Check if route is managed by IaC
+		existInState := false
+		for _, stateResource := range *resourcesFromState {
+			if resource.IsSameResource(remoteResource, stateResource) {
+				existInState = true
+				break
+			}
+		}
+
+		// Include resource if it's managed in IaC
+		if existInState {
+			newRemoteResources = append(newRemoteResources, remoteResource)
+			continue
+		}
+
+		// Else, resource is not added to newRemoteResources slice so it will be ignored
+		logrus.WithFields(logrus.Fields{
+			"route": route.String(),
+			"id":    route.TerraformId(),
+			"type":  route.TerraformType(),
+		}).Debug("Ignoring default internet gateway route as it is not managed by IaC")
+	}
+
+	*remoteResources = newRemoteResources
+
+	return nil
+}
+
+// Return true if the route's target is the default internet gateway (e.g. attached to the default vpc)
+func isDefaultInternetGatewayRoute(route *aws.AwsRoute, remoteResources *[]resource.Resource) bool {
+	for _, remoteResource := range *remoteResources {
+		if remoteResource.TerraformType() == aws.AwsInternetGatewayResourceType &&
+			isDefaultInternetGateway(remoteResource.(*aws.AwsInternetGateway), remoteResources) {
+			return route.GatewayId != nil && *route.GatewayId == remoteResource.TerraformId()
+		}
+	}
+	return false
+}

pkg/middlewares/aws_default_igw_route_test.go

@@ -0,0 +1,141 @@
+package middlewares
+
+import (
+	"strings"
+	"testing"
+
+	awssdk "github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/aws/awsutil"
+	"github.com/cloudskiff/driftctl/pkg/resource"
+	"github.com/cloudskiff/driftctl/pkg/resource/aws"
+	"github.com/r3labs/diff/v2"
+)
+
+func TestAwsDefaultInternetGatewayRoute_Execute(t *testing.T) {
+	tests := []struct {
+		name               string
+		remoteResources    []resource.Resource
+		resourcesFromState []resource.Resource
+		expected           []resource.Resource
+	}{
+		{
+			"default internet gateway route is not ignored when managed by IaC",
+			[]resource.Resource{
+				&aws.AwsDefaultVpc{
+					Id: "default-vpc",
+				},
+				&aws.AwsInternetGateway{
+					Id:    "default-igw",
+					VpcId: awssdk.String("default-vpc"),
+				},
+				&aws.AwsDefaultRouteTable{
+					Id:    "default-route-table",
+					VpcId: awssdk.String("default-vpc"),
+				},
+				&aws.AwsRoute{
+					Id:           "default-igw-route",
+					RouteTableId: awssdk.String("default-route-table"),
+					GatewayId:    awssdk.String("default-igw"),
+				},
+				&aws.AwsRoute{
+					Id:           "dummy-route",
+					RouteTableId: awssdk.String("default-route-table"),
+					GatewayId:    awssdk.String("local"),
+				},
+			},
+			[]resource.Resource{
+				&aws.AwsRoute{
+					Id:           "default-igw-route",
+					RouteTableId: awssdk.String("default-route-table"),
+					GatewayId:    awssdk.String("default-igw"),
+				},
+			},
+			[]resource.Resource{
+				&aws.AwsDefaultVpc{
+					Id: "default-vpc",
+				},
+				&aws.AwsInternetGateway{
+					Id:    "default-igw",
+					VpcId: awssdk.String("default-vpc"),
+				},
+				&aws.AwsDefaultRouteTable{
+					Id:    "default-route-table",
+					VpcId: awssdk.String("default-vpc"),
+				},
+				&aws.AwsRoute{
+					Id:           "default-igw-route",
+					RouteTableId: awssdk.String("default-route-table"),
+					GatewayId:    awssdk.String("default-igw"),
+				},
+				&aws.AwsRoute{
+					Id:           "dummy-route",
+					RouteTableId: awssdk.String("default-route-table"),
+					GatewayId:    awssdk.String("local"),
+				},
+			},
+		},
+		{
+			"default internet gateway route is ignored when not managed by IaC",
+			[]resource.Resource{
+				&aws.AwsDefaultVpc{
+					Id: "default-vpc",
+				},
+				&aws.AwsInternetGateway{
+					Id:    "default-igw",
+					VpcId: awssdk.String("default-vpc"),
+				},
+				&aws.AwsDefaultRouteTable{
+					Id:    "default-route-table",
+					VpcId: awssdk.String("default-vpc"),
+				},
+				&aws.AwsRoute{
+					Id:           "default-igw-route",
+					RouteTableId: awssdk.String("default-route-table"),
+					GatewayId:    awssdk.String("default-igw"),
+				},
+				&aws.AwsRoute{
+					Id:           "dummy-route",
+					RouteTableId: awssdk.String("default-route-table"),
+					GatewayId:    awssdk.String("local"),
+				},
+			},
+			[]resource.Resource{},
+			[]resource.Resource{
+				&aws.AwsDefaultVpc{
+					Id: "default-vpc",
+				},
+				&aws.AwsInternetGateway{
+					Id:    "default-igw",
+					VpcId: awssdk.String("default-vpc"),
+				},
+				&aws.AwsDefaultRouteTable{
+					Id:    "default-route-table",
+					VpcId: awssdk.String("default-vpc"),
+				},
+				&aws.AwsRoute{
+					Id:           "dummy-route",
+					RouteTableId: awssdk.String("default-route-table"),
+					GatewayId:    awssdk.String("local"),
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			m := NewAwsDefaultInternetGatewayRoute()
+			err := m.Execute(&tt.remoteResources, &tt.resourcesFromState)
+			if err != nil {
+				t.Fatal(err)
+			}
+			changelog, err := diff.Diff(tt.expected, tt.remoteResources)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if len(changelog) > 0 {
+				for _, change := range changelog {
+					t.Errorf("%s got = %v, want %v", strings.Join(change.Path, "."), awsutil.Prettify(change.From), awsutil.Prettify(change.To))
+				}
+			}
+		})
+	}
+}