Can't detach network interfaces

Question

I did the AWS misfits tutorial and I thought the cleanup would be as simple as deleting the Cloud Formation stack. However, items failed to delete so I am trying to clean them up manually to assist the Cloud Formation stack deletion.

I keep getting an error when trying to Detach the network interfaces (I am logged into the root account):

Error detaching network interfaces:

eni-0047gfhfgh8ab0e: You are not allowed to manage 'ela-attach' attachments. eni-0f4a46hgfha757e: You are not allowed to manage 'ela-attach' attachments. 

I am unable to delete my VPC without these being deleted.

The stack as a whole is failing to delete because of the following: The following resource(s) failed to delete: [InternetGateway, PublicSubnetTwo, VPC, GatewayAttachement, PublicSubnetOne].

Answer 1

I had the same issue, which gave me the following message:

This could be because there is a service in use which still uses the network interface. You could try some of the following things:

• Remove unused VPC links from API gateway
• Remove unused VPC Endpoint services
• Remove unused NAT gateways
• Remove unused ECS/EKS clusters
• Remove unused load balancers
• Remove unused EFS mounts

If that doesn't help, there is something wrong/stuck on the underlying OS, you should wait for it to resolve by itself or report it. I had an ENI deployed by a Lambda function after deleting the lambda function, the ENI got stuck. After some time I was able to detach the ENI.

Answer 2

AWS offers this bash script as help to find out the dependencies:

#!/bin/bash vpc="vpc-xxxxxxxxxxxxx"  aws ec2 describe-internet-gateways --filters 'Name=attachment.vpc-id,Values='$vpc | grep InternetGatewayId aws ec2 describe-subnets --filters 'Name=vpc-id,Values='$vpc | grep SubnetId aws ec2 describe-route-tables --filters 'Name=vpc-id,Values='$vpc | grep RouteTableId aws ec2 describe-network-acls --filters 'Name=vpc-id,Values='$vpc | grep NetworkAclId aws ec2 describe-vpc-peering-connections --filters 'Name=requester-vpc-info.vpc-id,Values='$vpc | grep VpcPeeringConnectionId aws ec2 describe-vpc-endpoints --filters 'Name=vpc-id,Values='$vpc | grep VpcEndpointId aws ec2 describe-nat-gateways --filter 'Name=vpc-id,Values='$vpc | grep NatGatewayId aws ec2 describe-security-groups --filters 'Name=vpc-id,Values='$vpc | grep GroupId aws ec2 describe-instances --filters 'Name=vpc-id,Values='$vpc | grep InstanceId aws ec2 describe-vpn-connections --filters 'Name=vpc-id,Values='$vpc | grep VpnConnectionId aws ec2 describe-vpn-gateways --filters 'Name=attachment.vpc-id,Values='$vpc | grep VpnGatewayId aws ec2 describe-network-interfaces --filters 'Name=vpc-id,Values='$vpc | grep NetworkInterfaceId 

My issue was a Transit Gateway Attachment and I could figure it out at some point.

Source: https://aws.amazon.com/premiumsupport/knowledge-center/troubleshoot-dependency-error-delete-vpc/