Previously, Amazon ECS provisioned one ENI per task that used the awsvpc network mode. As a result, the number of ENIs available on EC2 instances often became the bounding constraint despite there being ample vCPU and memory available for additional containers to utilize. Now, you can enjoy increased ENI density limits that range anywhere from 3 to 8 times the number of ENIs previously available.
The improved ENI densities are available in all regions where ECS is available. Please visit the AWS region table to see where Amazon ECS is available.
For more information on how to opt in and get started with increased ENI density limits, see Account Settings.