ECS task definitions should not use host network mode

How to fix it

• Can break clients: Containers lose the instance's ports and loopback services, and under awsvpc the service also needs a network configuration and target groups of type ip.

In the console

ECS → Task definitions → the family → the latest revision → Create new revision with JSON

networkMode

awsvpc (each task gets its own network interface) or bridge; none turns networking off, and only host fails

portMappings

Under awsvpc, containerPort only, as hostPort is ignored; under bridge, hostPort left out or 0 for a dynamic port

Task definition

The new revision, on each service's Update page and in each scheduled task; running tasks keep the old one

With Terraform

resource "aws_ecs_task_definition" "this" {
  family       = "example"
  network_mode = "awsvpc"

  container_definitions = jsonencode([{
    name  = "app"
    image = var.container_image
  }])
}