Handled case when instanceId is absent in network interfaces

builtin/providers/aws/structure.go

@@ -719,7 +719,9 @@ func expandPrivateIPAddresses(ips []interface{}) []*ec2.PrivateIpAddressSpecific
 //Flattens network interface attachment into a map[string]interface
 func flattenAttachment(a *ec2.NetworkInterfaceAttachment) map[string]interface{} {
 	att := make(map[string]interface{})
-	att["instance"] = *a.InstanceId
+	if a.InstanceId != nil {
+		att["instance"] = *a.InstanceId
+	}
 	att["device_index"] = *a.DeviceIndex
 	att["attachment_id"] = *a.AttachmentId
 	return att

builtin/providers/aws/structure_test.go

@@ -756,6 +756,23 @@ func TestFlattenAttachment(t *testing.T) {
 	}
 }
 
+func TestFlattenAttachmentWhenNoInstanceId(t *testing.T) {
+	expanded := &ec2.NetworkInterfaceAttachment{
+		DeviceIndex:  aws.Int64(int64(1)),
+		AttachmentId: aws.String("at-002"),
+	}
+
+	result := flattenAttachment(expanded)
+
+	if result == nil {
+		t.Fatal("expected result to have value, but got nil")
+	}
+
+	if result["instance"] != nil {
+		t.Fatalf("expected instance to be nil, but got %s", result["instance"])
+	}
+}
+
 func TestflattenStepAdjustments(t *testing.T) {
 	expanded := []*autoscaling.StepAdjustment{
 		&autoscaling.StepAdjustment{