Yes. It is possible to associate a service on Amazon ECS to an Application Load Balancer (ALB) for the Elastic Load Balancing (ELB) service. The ALB supports a target group that contains a set of instance ports. You can specify a dynamic port in the ECS task definition which gives the container an unused port when it is scheduled on the EC2 instance. The ECS scheduler will automatically add the task to the Application Load Balancer’s target group using this port.