Avoid to display false positive drift on instances when eip attached

pkg/driftctl.go

@@ -36,6 +36,7 @@ func (d DriftCTL) Run() *analyser.Analysis {
 		middlewares.NewVPCDefaultSecurityGroupSanitizer(),
 		middlewares.NewVPCSecurityGroupRuleSanitizer(),
 		middlewares.NewIamPolicyAttachmentSanitizer(),
+		middlewares.AwsInstanceEIP{},
 	)
 
 	logrus.Debug("Ready to run middlewares")

pkg/middlewares/aws_instance_eip.go

@@ -0,0 +1,61 @@
+package middlewares
+
+import (
+	"github.com/cloudskiff/driftctl/pkg/resource"
+	"github.com/cloudskiff/driftctl/pkg/resource/aws"
+	"github.com/sirupsen/logrus"
+)
+
+type AwsInstanceEIP struct{}
+
+func (a AwsInstanceEIP) Execute(remoteResources, resourcesFromState *[]resource.Resource) error {
+	for _, remoteResource := range *remoteResources {
+		// Ignore all resources other than aws_instance
+		if remoteResource.TerraformType() != aws.AwsInstanceResourceType {
+			continue
+		}
+
+		instance, _ := remoteResource.(*aws.AwsInstance)
+
+		if a.hasEIP(instance, resourcesFromState) {
+			logrus.WithFields(logrus.Fields{
+				"instance": instance.TerraformId(),
+			}).Debug("Ignore instance public ip and dns as it has an eip attached")
+			a.ignorePublicIpAndDns(instance, remoteResources, resourcesFromState)
+		}
+	}
+
+	return nil
+}
+
+func (a AwsInstanceEIP) hasEIP(instance *aws.AwsInstance, resources *[]resource.Resource) bool {
+	for _, res := range *resources {
+		if res.TerraformType() == aws.AwsEipResourceType {
+			eip, _ := res.(*aws.AwsEip)
+			if *eip.Instance == instance.Id {
+				return true
+			}
+		}
+		if res.TerraformType() == aws.AwsEipAssociationResourceType {
+			eip, _ := res.(*aws.AwsEipAssociation)
+			if *eip.InstanceId == instance.Id {
+				return true
+			}
+		}
+	}
+
+	return false
+}
+
+func (a AwsInstanceEIP) ignorePublicIpAndDns(instance *aws.AwsInstance, resourcesSet ...*[]resource.Resource)  {
+	for _, resources := range resourcesSet {
+		for _, res := range *resources {
+			if res.TerraformType() == instance.TerraformType() &&
+				res.TerraformId() == instance.TerraformId() {
+				instance, _ := res.(*aws.AwsInstance)
+				instance.PublicDns = nil
+				instance.PublicIp = nil
+			}
+		}
+	}
+}

pkg/middlewares/aws_instance_eip_test.go

@@ -0,0 +1,128 @@
+package middlewares
+
+import (
+	"reflect"
+	"testing"
+
+	awssdk "github.com/aws/aws-sdk-go/aws"
+	"github.com/cloudskiff/driftctl/pkg/resource"
+	"github.com/cloudskiff/driftctl/pkg/resource/aws"
+)
+
+func TestAwsInstanceEIP_Execute(t *testing.T) {
+	type args struct {
+		remoteResources    *[]resource.Resource
+		resourcesFromState *[]resource.Resource
+	}
+	tests := []struct {
+		name    string
+		args    args
+		expected args
+	}{
+		{
+			name:    "test that public ip and dns are nulled whith eip",
+			args:    args{
+				remoteResources: &[]resource.Resource{
+					&aws.AwsInstance{
+						Id: "instance1",
+						PublicIp: awssdk.String("1.2.3.4"),
+						PublicDns: awssdk.String("dns-of-eip.com"),
+					},
+					&aws.AwsInstance{
+						Id: "instance2",
+						PublicIp: awssdk.String("1.2.3.4"),
+						PublicDns: awssdk.String("dns-of-eip.com"),
+					},
+				},
+				resourcesFromState: &[]resource.Resource{
+					&aws.AwsInstance{
+						Id: "instance1",
+						PublicIp: awssdk.String("5.6.7.8"),
+						PublicDns: awssdk.String("example.com"),
+					},
+					&aws.AwsEip{
+						Instance: awssdk.String("instance1"),
+					},
+				},
+			},
+			expected: args{
+				remoteResources: &[]resource.Resource{
+					&aws.AwsInstance{
+						Id: "instance1",
+					},
+					&aws.AwsInstance{
+						Id: "instance2",
+						PublicIp: awssdk.String("1.2.3.4"),
+						PublicDns: awssdk.String("dns-of-eip.com"),
+					},
+				},
+				resourcesFromState: &[]resource.Resource{
+					&aws.AwsInstance{
+						Id: "instance1",
+					},
+					&aws.AwsEip{
+						Instance: awssdk.String("instance1"),
+					},
+				},
+			},
+		},
+		{
+			name:    "test that public ip and dns are nulled when eip association",
+			args:    args{
+				remoteResources: &[]resource.Resource{
+					&aws.AwsInstance{
+						Id: "instance1",
+						PublicIp: awssdk.String("1.2.3.4"),
+						PublicDns: awssdk.String("dns-of-eip.com"),
+					},
+					&aws.AwsInstance{
+						Id: "instance2",
+						PublicIp: awssdk.String("1.2.3.4"),
+						PublicDns: awssdk.String("dns-of-eip.com"),
+					},
+				},
+				resourcesFromState: &[]resource.Resource{
+					&aws.AwsInstance{
+						Id: "instance1",
+						PublicIp: awssdk.String("5.6.7.8"),
+						PublicDns: awssdk.String("example.com"),
+					},
+					&aws.AwsEipAssociation{
+						InstanceId: awssdk.String("instance1"),
+					},
+				},
+			},
+			expected: args{
+				remoteResources: &[]resource.Resource{
+					&aws.AwsInstance{
+						Id: "instance1",
+					},
+					&aws.AwsInstance{
+						Id: "instance2",
+						PublicIp: awssdk.String("1.2.3.4"),
+						PublicDns: awssdk.String("dns-of-eip.com"),
+					},
+				},
+				resourcesFromState: &[]resource.Resource{
+					&aws.AwsInstance{
+						Id: "instance1",
+					},
+					&aws.AwsEipAssociation{
+						InstanceId: awssdk.String("instance1"),
+					},
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			a := AwsInstanceEIP{}
+			if err := a.Execute(tt.args.remoteResources, tt.args.resourcesFromState); err != nil {
+				t.Fatal(err)
+			}
+			if ! reflect.DeepEqual(tt.args, tt.expected) {
+				t.Fatalf("Expected results mismatch")
+			}
+		})
+	}
+}