I'm having hard times adding instances that are created in my VPC and on a private subnet(no internet gateway attached to it) to ECS cluster.
Right now the only way I've managed to do this was by adding a public IP and have a NAT instance/gateway configured.
How do you use ECS clusters with private subnets?
I guess I've found the answer on the AWS documentation and it seems I need to use a NAT instance/Gateway :(
Another source and also the official documentaion
"...Container instances need external network access to communicate with the Amazon ECS service endpoint, so if your container instances are running in a private VPC, they need a network address translation (NAT) instance to provide this access. For more information, see NAT Instances in the Amazon VPC User Guide."